1967 barracuds, engine work

[bucki88]

My son and I have a 1967 Barracuda notchback with a stock 273 engine. We want to rebuild the engine and replace the factory heads with 318 heads with a casting No. of 302. Does anyone have any thoughts on this as to whether or not they will fit properly?

[greymouser7]

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[FONT='Times New Roman','serif'][FONT='Times New Roman','serif']318 Engine Build - A Parts Book 400HP 318[/font]

[FONT='Times New Roman','serif']This One Just Bolts Together[/font]
[FONT='Times New Roman','serif']Writer: Steve Dulcich
photographer: Steve Dulcich[/font]
Putting together a 400hp engine is a lofty goal; doing it with a pump-gas street 318 is an accomplishment. Bolting one together without any custom grinding, porting, special machining, or other smoke-and-mirrors trickery may seem impossible, but it makes it that much more palpable for the average guy. We’ve featured plenty of more advanced engine builds, but the beginner may wonder how to get there with all the custom mods involved. Well, this one is for the Average Joe--a straight bolt-together deal even a first-time engine builder can put together. Ours made exactly 400 hp with a little tuning on the dyno. Yours will make the same, if the battle plans laid out here are followed exactly.
Why build a 318? Some may argue there is never a reason to build the Mopar 318. When the time comes to rebuild a small-block, the 318 should always be cast aside in favor of a 360. We won't argue. A 360--built properly--will always have a torque advantage over a 318. However, 318 cores are free for the asking, and that offers some economic incentive. But the real motive usually isn't a matter of cost. The bottom line is like it or not, 318s are being rebuilt by enthusiasts every day. Some guys have a certain sentimental attachment to these cute little engines. Sometimes it's just the desire to retain the car's original power plant. And some guys dig the idea of blowing doors in with just a 318. Count us in that last group. We were intrigued with working out a combo that shows how to really make one run. Our goals were straightforward:
[FONT='Times New Roman','serif'] the engine would be based on a regular 318. [/font]
[FONT='Times New Roman','serif'] the engine must run on 91-octane pump gas or less. [/font]
[FONT='Times New Roman','serif'] the camshaft must be daily-driver Street able, at least in a hot-rod sense. [/font]
[FONT='Times New Roman','serif'] the build will not include any exotic, rare, unusual, or excessively expensive parts. [/font]
[FONT='Times New Roman','serif'] The parts will be bolted on out of the box with no custom tricks, massaging, or porting. [/font]
[FONT='Times New Roman','serif'] The final output would break the 400hp barrier. [/font]
The Build
The subject of our build was the engine from our '68 Barracuda fastback. The 318 was putting out almost 200 hp at the rear wheels with an antique Edelbrock Street Master intake and four-barrel carb, along with a dual exhaust featuring the stock exhaust manifolds. The output wasn't terrible, but the blue smoke and blow-by certainly were. The engine was just worn out, as we found when the heads were popped to reveal well over .010-inch bore wear. It was the perfect candidate for our buildup. With a goal of 400 hp under the above noted constraints, we had to consider every aspect of the combo very carefully.
[FONT='Times New Roman','serif']318 Engine Build - A Parts Book 400HP 318[/font]

[/font][FONT='Times New Roman','serif']Starting at the bottom, the contents of the block had to work together optimally in order to reach our goals. Piston choice is a critical aspect of any build, and in the case of the 318 the choices are limited. Our requirements were a flat-top piston at zero deck, which would provide a desired boost in compression ratio, while also ensuring that we would have an ideal quench clearance to make the most of combustion efficiency. Stock and stock replacement pistons place the pistons so far down the hole, that even with massive milling; the goal of a zero deck is out of reach. Fortunately, Keith Black offers a hypereutectic 318 piston that fits our criteria (KB 167). The assembly can be brought to zero deck with modest block machining, and the pistons are a commonly available shelf part at a practical price. To provide the combustion seal and desirable friction characteristics, high-quality moly rings are needed. We looked no further than Federal Mogul's offerings, opting for their pre-gapped moly rings. Though file-fit rings can be had for our bore size, these rings are more in keeping with our requirement for moderate cost and a bolt-it-together assembly.
A zero-deck block is a waste of time without a closed-chamber quench head to go along with it. While practically all high performance aftermarket heads are of this configuration, we sought to reach our goals without the expense of aftermarket aluminum heads. Looking at the production options, the field is limited since the vast majority of stock small-block heads were of the open-chamber variety. The only exception in the LA-series heads is the closed-chamber, late-model, 318 two-barrel 302 castings. The ports and valves in these heads do not offer sufficient flow to meet our goals. With serious porting and larger valves installed, the 302 heads could get us there, but these mods are contrary to our goal of a bolt-together package. However, the later Magnum heads also feature closed chambers, and with their 1.92/1.625-inch valve combination, these heads do have the flow to support 400 hp in the right combination. The Magnum heads offer numerous advantages in this application. With a chamber volume of 59 cc, these heads will offer about 10:1 compression ratio when combined with a zero-deck short-block utilizing typical .040-inch head gaskets. That's about where we figured we'd need to be to make the power number. The Magnum-head layout features excellent rockers with an added bonus of 1.6:1 in ratio, as opposed to the LA engine's 1.5:1. This aids our effort to reach the 400hp mark. Other Magnum pluses are lightweight, 8mm stem valves and machined valve-cover rails with ten valve-cover attachment bolts to minimize the potential for oil leaks.
[FONT='Times New Roman','serif']318 Engine Build - A Parts Book 400HP 318[/font]

[/font][FONT='Times New Roman','serif']With this, we had the basis of our build-up: a zero-deck 318, sporting Magnum heads and an MP single-plane intake. All that was left was to select enough cam to do the job. Getting to our output goal would be easy with a huge stick, but we were working within reasonable limitations. The objective was to put together a combo that would work well on the street. Another consideration was the retainer-to-guide clearance of the Magnum heads. The retainer in a stock Magnum head will physically hit the valve stem seal at .530-inch of lift, thus putting a ceiling on cam selection. Though the guide can easily be cut down for more clearance, we would be getting into custom mods, which we were seeking to avoid. In fact, the lift limitation would allow about as fat of a camshaft as we were willing to run. Keep in mind, nearly all cam specs listed for Mopar small-blocks are calculated at the LA-engine's 1.5:1 ratio. With the higher 1.6:1 ratio of the Magnum engine, it doesn't take a huge cam to use up all the available clearance. We selected a Competition Cams 280H Magnum camshaft, which is a single-pattern grind featuring 280 degrees of rated duration and 230 degrees of duration at .050-inch tappet rise. This cam is advertised as having .480-inch lift, but with the higher-ratio Magnum valvetrain, theoretical lift goes up to .512-inch. It seemed like the ideal cam for our combo. We liked the single-pattern profile as a compliment to the Magnum heads' good exhaust flow ratio, and that the cam was maxing out the lift potential of the out-of-the-box Magnum heads.
With our combination penciled out, we brought our 318 to Precision Speed and Machine in Delano, California, for machining. Since we were going to use new Magnum cylinder head assemblies from Mopar Performance, the efforts were concentrated upon the bottom end. We elected to go .040-inch oversize in the bores, and had the block bored and honed by Precision with moly rings in mind. We upgraded the connecting rods from the weak early 318 pieces, moving to the readily available later ('73-and-up) rod shared by the 318 and 360. These rods are virtually indestructible in an application such as this. Another upgrade was to swap the stock 318 crank for a forged piece, since we happened to have one pulled from a 273. The early 273 cranks have a different torque converter register, which creates problems in an automatic application, but it is readily compatible with four-speed components. The rotating assembly balanced fine.
Precision inspected and reconditioned the stock rods and installed a set of high-strength ARP rod-bolts. Special care was taken in selecting the rods and resizing to ensure a set of rods with virtually identical center-to-center length. This is critical in setting up a zero-deck engine. Precision line honed the block to exact tolerances, and then square decked the block to put the pistons dead flush with the block at TDC. The machining checked out exact. The final assembly was a breeze, as should be expected with production-based pieces and top-quality machine work.
Making the change to Magnum heads is a simple swap. All stock components can be used; however, Magnum engines oil the valvetrain through the pushrods as opposed to LA-style engines. Since all Magnum engines were equipped with factory hydraulic-roller camshafts, using the Magnum heads in conjunction with an LA block and a hydraulic flat tappet cam requires custom-length pushrods. Mopar performance sells a pushrod kit for this application (PN P5007477). We mocked up our engine combo (taking into account the block decking) and found that Comp Cam's number 7960 pushrods at 7.650-inch length were an ideal fit. Another distinct feature of the Magnum design is a vertical intake bolt angle, requiring a Magnum-specific intake manifold. There are not as many choices in Magnum manifolds as with the traditional LA small-block. Mopar Performance offers a dual-plane, as well as a racy single-plane intake for this application. We opted for the single-plane. The single plane would undoubtedly cost precious torque lower in the rpm range, but we just didn't think the dual-plane was the piece to make our target output. Word has it Edelbrock is introducing a Performer RPM intake for this application, and it should prove to be an excellent alternative.
[FONT='Times New Roman','serif']318 Engine Build - A Parts Book 400HP 318[/font]

[/font][FONT='Times New Roman','serif']Putting It Up
To see if this 318 would meet our lofty goals, we brought our fresh mill to Westech's engine dyno facility to post some numbers. The assembled long-block received an MSD distributor and wires, a set of tti 15/8--13/4-inch step headers, and a 750 Mighty Demon carb--all top components we were confident using. The 318 cracked to life, and we ran the engine through the normal break-in cycle with the distributor set to provide 34 degrees of total timing. Idling down, the 318 sounded sweet commanding 10.5-inches of vacuum and exhibiting a mild loop. With the first real power pull, we recorded 383 hp at 6,200 rpm, stout output but a little shy of our goal of 400 hp. One thing was clear, the little 318 did love to rev. A timing loop followed, as we sought to zero in on the ideal timing and found the best overall curve with total advance set to 36 degrees. Power nudged up only slightly, now reading 385 at the same 6,200 rpm. A jetting loop followed, but there wasn't anything to be found after making several jet changes.
We noted the fresh engine was producing a maximum of 95 psi of oil pressure hot with the 20w-50 oil we used for break-in. It seemed as though a lower viscosity oil would be worth a couple of numbers, and better still, a nice synthetic may add even more output. We drained the sump for a fill of 10w-30 Royal Purple and found more than we expected, with power now up to 394 at 6,100 rpm. We were tantalizingly close to the 400 mark, and still had a trick or two to try. A Wilson 1-inch tapered spacer was sandwiched between the intake and carb, and we hit pay dirt--400 hp on the nose at 6,150 rpm!
Dyno Results
Superflow 901 Dyno
Tested At Westech

Mopar 318[FONT='Times New Roman','serif'][/font]

RPM[FONT='Times New Roman','serif'][/font]
HP[FONT='Times New Roman','serif'][/font]
TQ[FONT='Times New Roman','serif'][/font]
[FONT='Times New Roman','serif']3,000[/font]
[FONT='Times New Roman','serif']190[/font]
[FONT='Times New Roman','serif']332[/font]
[FONT='Times New Roman','serif']3,500[/font]
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[FONT='Times New Roman','serif']4,000[/font]
[FONT='Times New Roman','serif']286[/font]
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[FONT='Times New Roman','serif']4,500[/font]
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[FONT='Times New Roman','serif'][FONT='Times New Roman','serif']4,900[/font]
[FONT='Times New Roman','serif']357[/font]
[FONT='Times New Roman','serif']382[/font]
[FONT='Times New Roman','serif']5,000[/font]
[FONT='Times New Roman','serif']363[/font]
[FONT='Times New Roman','serif']381[/font]
[FONT='Times New Roman','serif']5,500[/font]
[FONT='Times New Roman','serif']388[/font]
[FONT='Times New Roman','serif']371[/font]
[FONT='Times New Roman','serif']6,000[/font]
[FONT='Times New Roman','serif']398[/font]
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[FONT='Times New Roman','serif']6,200[/font]
[FONT='Times New Roman','serif']400[/font]
[FONT='Times New Roman','serif']339[/font]
[FONT='Times New Roman','serif']6,500[/font]
[FONT='Times New Roman','serif']393[/font]
[FONT='Times New Roman','serif']318[/font]

[FONT='Times New Roman','serif']318 Engine Build - A Parts Book 400HP 318[/font]

[/font][FONT='Times New Roman','serif']Power Squeeze
While 400 hp from a bolt-together 318 may seem like plenty, we figured with a little go-fast gas our little engine could go hunting for some big-block game. With the hypereutectic KB pistons, we decided to keep the nitrous moderate and sane, just enough juice to stalk some of the hardier street beasts we may encounter. Be aware that KB has very specific ring end gap requirements for nitrous use, and these must be followed during the build if any kind of life expectancy is to be had from the engine with nitrous. We selected a Nitrous Works jet-metered plate system, a quick and easy addition to any engine. The plan was to add 100 hp to our normally aspirated output, not an excessive amount, but enough to really notice.
The Nitrous Works recommended jets for a hundred horse shot were installed. Installing the plate system was only a matter of unbolting the carb, slipping the nitrous plate between it and the manifold, and then running the fuel and nitrous lines to their respective solenoids. The solenoids were wired to a remote switch, and we were good to go. With an aim towards being conservative, the fuel supply was switched to 100 octane, and the MSD ignition was set to provide 8 degrees of retard upon the activation of the nitrous system. Adding nitrous at a low rpm can lead to excessive cylinder pressure, so we planned on hitting the nitrous at 4,700 rpm, which would equate to just out of the hole on the dragstrip and above the shift recovery rpm going down the track. The nitrous system delivered on its promise, boosting output to just above the 500hp mark, and maintaining a flat power curve up to our self-imposed redline of 6,400 rpm.

Nitrous Output[FONT='Times New Roman','serif'][/font]

RPM[FONT='Times New Roman','serif'][/font]
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TQ[FONT='Times New Roman','serif'][/font]
[FONT='Times New Roman','serif']5,000[/font]
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[FONT='Times New Roman','serif'][FONT='Times New Roman','serif']http://theserviceadvisor.com/part/reman/index.html [/font]
[/font][FONT='Times New Roman','serif']http://www.dynamic-pc.com/mopar/links.php[/font]
[FONT='Times New Roman','serif']http://www.mopar.net/showthread.php?t=105353[/font]
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[FONT='Times New Roman','serif']http://www.compcams.com/Community/Articles/[/font]
[FONT='Times New Roman','serif']http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/index.html[/font]
[FONT='Times New Roman','serif']http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/index.html[/font]
[FONT='Times New Roman','serif']http://theserviceadvisor.com/part/reman/plymouthbesttsamop_318lb_4.html [/font]
[FONT='Times New Roman','serif']http://www.sweptline.com/tech/engine1.html Hiperformer engines[/font]
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[greymouser7]

[FONT='Times New Roman','serif']http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build [/font]

[FONT='Times New Roman','serif']What Can I Do To My 318?
The mild but spirited 318 combo[/font][FONT='Times New Roman','serif'][/font]

[FONT='Times New Roman','serif']The 318 can be an impressive performer. Start by getting the following books: Mopar Performance catalog, Mancini Racing catalog and HP Books How to rebuild your small block Mopar. So, we'll start with the readily available 1970-1980 318 as a base. These are about 8.5 to 1 compression motors with flat top pistons. These pistons have a compression height of 1.740" from pin centerline to piston top. For the economy back yard performance motor, the factory flat top pistons can be reused. There are also several inexpensive cast pistons on the market to raise the compression up to 9 or 9.5 to 1. If upgrading to these pistons, have the block bored .020" or .030" over at your local machine shop for new oversize pistons.

Heads
For the heads, you have about 3 routes to go here. The original heads can be reworked. Have them checked real close as cracked heads from the late 1970's are not uncommon, especially from the lean burn motors. The small valves will have to be replaced with larger valves from a 360, 1.60" exhaust and 1.88" intake. Mancini Racing has inexpensive stainless valves in stock which are perfect for this upgrade. Have your machine shop re-cut the valve seats in your heads for the new valves, be sure to get a high performance valve job which has a 70 degree throat cut(some shops use a 65 degree cut which is o.k.). When you get the heads back from the shop, take a look in the throat below the valve seat. Where the throat cut ends at the casting, smooth out this transition with a dremal tool or drill with port polishing sanding rolls. Not too much but smoothing this helps flow a bunch. The best head choice would be the swirl port 318 head (casting 302) made from about 1985 thru about 1991. The 302 casting has a closed chamber that is heart shaped. This is the pre magnum head. Again, treat it like the above 318 head. The 360 head is another choice. There are tons of these available from the 1970's and are pretty cheap. Keep the small 1.88" valves as port velocity will be higher than changing to the 2.02". Have a competition valve job done, clean up the throat as above. Now the 360 heads have a much larger combustion chamber volume, averaging around 72 cc vs. the 318's 63-65cc. You will have to get these heads milled a bunch to keep what compression you had. Without milling the heads, you'll end up around 7.8 to 1 compression(absolutely no ping though!). So, how much to mill? For each .0048" milled, you remove 1 cc. Looks like you need 7cc removed which is .034". I suggest going to .040" Now as the heads surface is milled, the ports get closer to each other since they are installed on a V engine. Have the intake surface of the heads milled .0095" for each .010" milled from the head/block surface. This will keep the ports in line. Which ones to use? The #302 swirl port castings are the best choice for a mild 318 buildup if you are having them ported. If you are going the un-ported route, go with the 360 heads but have them milled.

Intakes
For the intakes, it depends on which heads you use. If you use the 318 heads which have the small ports, you should use a small port intake for a smooth transition. The Edelbrock Performer is the best choice. If you use the 360 heads, there are only three good choices: MP M1 dual plane, Edelbrock RPM and the factory iron 4 bbl. I would suggest the M1 since it produces more torque and mid range.

Cams
Well, there are a million cam choices out there. The two I would suggest are the following Mopar Performance cams:

P4452759 .430"/.450" lift, 260/268 duration

P4452761 .450"/.455" lift, 268/272 duration

Both of these cams have a lobe separation angle(LSA) of 110 and a 108 intake centerline(ICL). The "759" cam was developed to make more torque than the original 340 grind with the same horse power. The "761" cam was developed to make the same torque as the 340 grind but more h.p. Make sure you degree the cam in, very important. The 108 ICL is the installed point the factory suggests. My cam choice would be the "761". It will have a lope idle. Be sure to use a dual chain/gear set and match the valve springs to the cam choice. Either of the above cams can use 340 replacement valve springs or Mopar Performance P4120249.



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[FONT='Times New Roman','serif']Carb[/font][FONT='Times New Roman','serif']
Again there are tons of choices. The Holley 600 (1850) or 750(3310) vacuum secondary is a popular choice. My favorite would be an AVS Carter, they are user friendly. A TQ from a 340 will do well, be sure it is from a 340 or install 340 rear jets(around .126" I think). Carter AFB or Edelbrock Performer carbs are easy to work on, run great and are available new.

Exhaust
Headers are a must. The 318 works well with the economical "fit all" type with 1 5/8" primary tubes. Be sure to use 2 1/4" dual exhaust with high flow mufflers like Walker Super Turbo or Flowmaster Mufflers.

Ignition
The Mopar electronic ignition is a great system Do not use the lean burn system. You should recurve the ignition by installing two light springs in the distributor in place of the factory springs. These springs can be gotten from MP as P4007968. Also use the "orange box", P4120505. Set the ignition at 35 degrees total. Use the MP timing tape on your dampener, disconnect the vacuum advance, bring up the rpm to 2,500, set the 35 mark on the dampener to the -0- mark on your timing cover. When finished, be sure to reconnect your vacuum advance.



DYNO TESTED 318
The proof is in the dyno testing. This engine really performs well and produces the same power as a high compression 340.

Mid 1980's non roller cam 318, rebuilt with stock crank and rods. Arp rod bolts added when the rods were reconditioned. Crank turned .010"/.010". Flat top cast pistons were used. After the block and heads were milled to true up, a 9.2 to 1 compression was achieved. The heads are the #302 swirl port casting from a 1987 318. The heads have the larger 1.88"/1.60" valves installed, competition valve job and were treated to a full port job. Intake is the Edelbrock Performer. Carb is the Holley #3310 750cfm vacuum secondary. Headers are basic fit all 1 5/8" primary tube. Cam is the Mopar Performance P4452761 with .450"/.455"lift , 268/272 duration. Timing was set at 35 degrees total for the dyno test.

330 horse power @5750rpm.

How does that sound? The exact motor was also dyno run with 360 heads installed and it produced 290 horse power @5750 rpm. That shows how port velocity is so important. But...290 horse power is no slouch for a 318. Most of the same information presented here can be applied to the 273.[/font]

[greymouser7]

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[FONT='Times New Roman','serif']http://www.popularhotrodding.com/enginemasters/articles/mopar/0667em_mopar_318_engine/index.html [/font]
[FONT='Times New Roman','serif']Mopar 318 Engine - Cheap as Dirt[/font]

[FONT='Times New Roman','serif']415 hp from a Street 318[/font]
[FONT='Times New Roman','serif']By Steve Dulcich[/font]
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One man's trash is another's treasure, and when it comes to bottom feeding in the world of Mopar engines the 318 seems like the biggest bargain in town. Know for efficient grocery getting in modest transportation, the musclecar aura never kissed the 318. Though the 318's long production run began in 1968, poised perfectly to participate in the height of the musclecar era, it was only available as a two-barrel economy until the deep dark days of the smog era in 1978. Without the cool reputation as a powerhouse like the bigger 340, 318s are routinely plucked from all manner of Chrysler products, and are practically handed out for haulage in Mopar circles. Be that as it may, there are some true 318 devotees in the Mopar world, impressed by the efficiency and long service this loyal mill provides.
So what's wrong with the 318? Obviously, it's a little light on displacement, but not compared to some more highly revered engines of the past-302 Chevys or Boss Fords, for instance. The most commonly heard objection is that the bore is small, creating shrouding that hurts flow and makes big power impossible, since at 3.91-inches it's not quite at the "magic" 4.000-inch mark. Yeah right-tell it to the LS1 crowd. Those engines are known for their breathing despite an even smaller bore. With Mopar's factory18 degree valve angle, this is pretty much a moot point for most street builds. The fact is a 318 can be the basis for a nice small-displacement, high-rpm power plant. With its short3.31-inch stroke, high rpm are natural. A case can be made for a small-displacement street engine that's fuel efficient by virtue of its modest size, but piles on the power on demand when needed, by winding the revs up the scale. With the 318 Mopar as a base, such an engine can be built for a ridiculously low price. Better still, you will always bathe underdog, and there is nothing like talking smack when putting the hurt on the big boys with a "lowly" 318.
Our goal was to build a hot street engine, using the attributes of the factory package to its best advantage, keeping the build as cheap as practical. All 318s use long 6.123-inchrods, though the 1973 and later engines had the stronger but heavier 340/360 forgings, which are better. These later rods are stout from the factory, and toy with engine speeds on the order of 6,500 rpm, and even a little more. Nearly all 318s came with cast cranks, and here again the factory stuff can take 6,500 rpm handily. In fact there is nothing in the stock engine that can't work exceptionally well in that rpm range, including the lubrication system, electronic ignition, and even the production valvetrain. I guess you can fairly say that these engines are all 6,500-plus-rpm screamers just waiting to be unleashed; here's how we did it.
The Build
Low compression is a drawback of any 318, with all of the factory pistons dwelling deep in the hole at TDC. The low-cost remedy here is a set of KB 167 flat-top pistons, which allow for a zero deck with minimal milling. We had the guys at Precision Speed and Machine, in Bakersfield, California, punch our virgin 318 block 0.040-inch over, to3.950-inch (getting close to 4.000-inch there, aren't we?), and then zero deck the block. With this overbore, the 318 grows to 324 cid. This minimal level of machining prep will usually be all that is required to build a hot street 318. We used a 273 steel crank in our engine, only because we found it in the dirt at the local bone yard, but any of the factory cast cranks are more than up to the job. To complete the short-block, we had the rods reconditioned with new Pioneer bolts, and used a factory windage tray, as well as homemade sheet metal baffle in the pan to prevent oil slosh. A summery of bottom-end mods is a pretty short list, basically all we did was put the flat top pistons in, milled for zero deck, balanced it, and put it back together with all re-conned factory stock stuff. Moving on to the top-end, here is where you might expect to find the secrets to making the big power put down by this little engine. Well, normally a really trick set of heads can work wonders, but here we just used a bone yard set of plain old 360 Mopar smog heads. After all, few guys will cap a $500 short with a $1,500 set of heads. All of those '70s-80s360 heads essentially carry the same port layout of the high performance 340, and as far as run-of-the-mill production iron of the era, they are about as good as it gets. In fact, these old-school heads have a big advantage over the later castings. The pushrod constriction is much less intrusive than that found on engines spawned in the hydraulic roller era, far less than even the Magnum heads of the '90s. The bottom line is that these360 heads have plenty of intake port for a very stout 318.
All of the 360 Mopar heads came from the factory with 1.88-inch intake valves, 1.600-inch valves at the exhaust, and big open chambers, at 72cc. To step things up, we started by having the heads machined for 2.02-inch intake valves. Some weird urban legend has it that 2.02-inch intake valves will not fit a 318, or that bore notches are required. Actually, even a standard-bore 318 will swallow valves of this size, so no problem for our 0.040-over mill. After the seat machining, the heads received a little porting, consisting of a basic bowl blend, and some work at the pushrod area. Far from an all-out effort, these heads got little more than a swizzle of the carbide cutter-not even the ugly guide bosses were cut. These modifications may not seem like much, but it was enough to tap well into the potential of the castings, and produce respectable flow (See: FlowChart). To reduce the chamber volume for our small displacement engine, the heads were milled fairly heavily to 60cc.

[FONT='Times New Roman','serif']Mopar 318 Engine - Cheap as Dirt

[FONT='Times New Roman','serif'] [/font]
Tallying up so far we had a stock short with flat-tops, and a set of milled junkyard heads with bigger intake valves and very modest porting. It may not sound like much, but this is good stuff for a 318 build. The next consideration was the camshaft. Here we gravitated towards a hydraulic flat tappet, which may not be romantic, but is certainly budgeting conscious. A solid flat tappet certainly would have offered even more rpm potential, but a hydraulic allows us to use the factory valvetrain. While the OEM valvetrain is non-adjustable, and looks as low-tech as it gets, it is extraordinarily lightweight, and being a shaft system, it's as stable as it comes. With a hydraulic cam, the ugly stock stuff will out-rpm virtually anything from the aftermarket. So what's wrong with the 318? Obviously, it's a little light on displacement, but not compared to some more highly revered engines of the past-302 Chevys or Boss Fords, for instance. The most commonly heard objection is that the bore is small, creating shrouding that hurts flow and makes big power impossible, since at 3.91-inches it's not quite at the "magic" 4.000-inch mark. Yeah right-tell it to the LS1 crowd. Those engines are known for their breathing despite an even smaller bore. With Mopar's factory18 degree valve angle, this is pretty much a moot point for most street builds. The fact is a 318 can be the basis for a nice small-displacement, high-rpm power plant. With its short3.31-inch stroke, high rpm are natural. A case can be made for a small-displacement street engine that's fuel efficient by virtue of its modest size, but piles on the power on demand when needed, by winding the revs up the scale. With the 318 Mopar as a base, such an engine can be built for a ridiculously low price. Better still, you will always be the underdog, and there is nothing like talking smack when putting the hurt on the big boys with a "lowly" 318.
Our goal was to build a hot street engine, using the attributes of the factory package to its best advantage, keeping the build as cheap as practical. All 318s use long 6.123-inchrods, though the 1973 and later engines had the stronger but heavier 340/360 forgings, which are better. These later rods are stout from the factory, and toy with engine speeds on the order of 6,500 rpm, and even a little more. Nearly all 318s came with cast cranks, and here again the factory stuff can take 6,500 rpm handily. In fact there is nothing in the stock engine that can't work exceptionally well in that rpm range, including the lubrication system, electronic ignition, and even the production valvetrain. I guess you can fairly say that these engines are all 6,500-plus-rpm screamers just waiting to be unleashed; here's how we did it.
Mopar’s have another advantage, and that is the 0.904-inch tappet diameter, which translates to about 8 percent more intensity at the valve with a cam designed to make use of the large lifter diameter. COMP has just the cams for the job, with their Mopar-only XEHL series. This is a variation of the popular Xtreme Energy cam series, but built to provide the additional intensity the 0.904-inch lifters allow. We went with the smallest of this series, the XE275HL, specing out at 231/237-degrees duration at 0.050, and 0.525-inch lift, on a 110 degree lobe separation angle. This duration level is enough to give a noticeable chop at idle, but not temperamental enough to make you insane in day-to-day driving. To cope with the aggressive rate of this cam, we used a fairly significant level of spring load for a flat tappet, deciding on a set of COMP 972 single springs installed at1.750-inch, for 140 lbs on the seat and 310 lbs over the nose.
The final aspect of the build to consider is the induction, and here past experience has taught us that there is no beating an Edelbrock Performer RPM AirGap in the street range up to 6,500 rpm. That much was a given, but motivated by ultimate cheapness we bolted-on a TransDapt adapter plate, which allowed us to mount a factory Mopar ThermoQuad carb. The TQ carb is actually a fine unit, and the one we used is the larger version rated at850 cfm of airflow, though an 800-cfm unit was also OEM equipment. That may seem like a huge amount of carb for a 318, but an odd characteristic of the TQ is that it allows monstrous capacity to work on seemingly impossibly small combinations. Finally a set of TTI headers with 1 5/8- to 1 3/4-inch primaries were obtained to handle the exhaust, and we had our combo. On paper, it seemed pretty tame, a flat-top piston 318, with mildly reworked iron 360 smog heads, a hydraulic flat tappet, an Edelbrock two plane, a stock four barrel, and headers. We knew better.
Running the Numbers
When we brought our 318 to Westech Performance Group for testing, the attractively detailed 318 Mopar drew some interest, and naturally a few questions about the combination. We revealed it was a 318, basically a factory short-block put together with KB flat-tops and a hydraulic flat tappet, mildly ported ordinary factory 360 heads, and the four-barrel setup with the ThermoQuad visible to all. By the specs, it didn't seem like much, especially being "only a 318", so there was some serious doubt when we confidently stated that it should make over 400 hp. After all, mildly reworked 318s don’t make that kind of power, especially with some junkyard heads. Well, it didn't take long to silence the skeptics, when the engine was broken in and then loaded against the brake for the first power pulls. With out baseline combination, the engine zinged-up the rpm scale to make 400 hp at 6,200-6,300 rpm.
We could see that the 318 was doing exactly what we expected-making lots of power and rpm. We could also see from the dyno sheets that the factory ThermoQuad carburetor was running at least a point too rich, and it was time to make a decision. There were a few things we wanted to try while on the dyno, and we only had one day reserved for testing, and about half of that was already eaten just setting the Mopar mill up on the dyno, and getting our baseline figures. Experience has taught us that playing with the ThermoQuad could easily soak the rest of the day in tuning, so we decided to substitute a Mighty Demon 750-cfm carb, primarily for its easy tuning changes. A 1-inch open spacer was used to mimic the 1-inch adapter that had been necessary with the ThermoQuad. With some quick jet changes of the Demon to get our mixture in the bull’s-eye, we had 406hp showing at the same 6,200-6,300 rpm peak.

[FONT='Times New Roman','serif']Mopar 318 Engine - Cheap as Dirt

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Inside, the engine still had its fill of 20-50 conventional diesel oil used for break-in. We figured the little Mopar mill had gotten over the critical flat tappet cam break-in period by now. There was the potential for a little more power with the oil change, so we switched to Lucas 5-20 full synthetic oil for our next series of runs. The synthetic offers a lower viscosity, and presumably lower friction, which we hoped would result in some additional power by a reduction of parasitic drag. The oil change proved to be a positive step, with output now reaching 412 hp at the exact same power peak.
Dyno operator Steve Brule suggested we might gain some additional power by swapping the 1-inch open spacer for a tapered combination spacer. We grabbed a 4150-sized HVH-SuperSucker spacer from our shelf, and made the change. The SuperSucker provides a tapered entry from the carb into the plenum; with some combinations this can add incrementally to the output. It proved to be the case with our 318 Mopar combination, taking peak output to 415 hp at 6,300 rpm, which would prove to be the best numbers of the day.
Our 318 cam delivered a rated 0.525-inch lift with 1.5:1-ratio rockers. Under the valve covers we were running the stock Mopar hydraulic rocker valvetrain, which we just cleaned and re-used, including the stock solid bar 5/16-inch pushrods. Although this non-adjustable valvetrain looks crude, test after test has proven it to be remarkably capable in hydraulic cam applications where adjustability is not strictly required. These stamped-steel rockers are lighter than anything from the aftermarket, and the ingenious shaft-mount system lets the rockers ride with virtually no clearance on broad bearing surface at the lower half of the rocker, sliding on a film of oil much like a main bearing. Friction at the shaft is virtually nil, and the stability is excellent. Still, we wanted to see if a little more lift could be added with a higher rocker ratio, so we swapped to a set of aluminum1.6:1 roller rockers. This would get us to 0.560-inch lift.
The rocker change didn't work out, and in fact, the engine's effective rpm range dropped dramatically, down to 6,100 rpm, as compared to the easy and clean 6,700 rpm ceiling(the limit of our test range, not the engine's rpm capabilities) with the factory stock 1.5:1rockers. We tried setting the lash to zero, to curb lifter pump-up, but it didn't help. What went wrong? In my experience, there are definite limits to how much intensity can be used with a hydraulic lifter, be it a flat tappet or roller. We were over that line with our overall combination.
With the super-quick 0.904-inch cam lobe profile, even with the 1.5:1 rockers we were already reaching a very high lift when considering the overall duration. As previously noted, these "0.904-profile" lobes are about 8 percent faster than high intensity 0.842-profile lobes, and the high-ratio rockers add another 7 percent. At the resultant 0.560-inchlift on a 231 @ 0.050 lobe, with only 275 rated seat duration, the valve action is well into the range of a very aggressive solid roller, far faster, in fact, through the early stages of the valve event. The result is valvetrain instability, which the hydraulic mechanism of the lifter cannot cope with. We've been through it before, and increased spring load will do little to help the situation. Besides, with longevity in mind, our COMP No. 972 springs were at the limit of loads we'd run in a street flat tappet application. If hunting for the far reaches of hydraulic cam intensity and rpm, the direction has to be mass reduction throughout the valvetrain, including lightweight valves. The 3/8-stem street valves and now heavier rockers just weren't gong to cut it with this combination.
[FONT='Times New Roman','serif']Should we be disappointed that the higher ratio rockers didn't work? Maybe not, since it told us that the factory stuff, when combined with the fast COMP lobe profiles, is in the upper range of the potential available. While more would definitely be possible with trick lightweight components like valves, these items are somewhat out of the budget nature of this build. It also reinforces the value of the stock Mopar valvetrain. It represents a significant cost savings compared to other makes of engines where a valvetrain swap is virtually mandatory for survival with a high performance cam. Thinking about the results, we were pretty happy with the 415 street able hp and 6,500-plus rpm capabilities we got from Chrysler's neglected 318, especially considering how much of this engine consists of nothing more than mundane factory production parts.[/font]
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[FONT='Times New Roman','serif'][FONT='Times New Roman','serif']There is no debate that a Demon carb is easier and quicker to tune than the TQ, and time was ticking. We made a quick swap to a 750 Mighty Demon atop a Wilson spacer, and within a couple of jet changes had 406 hp at 6,200-6,300 rpm.[/font][/font]
[FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][/font][/font]
[FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif']An oil change to Lucas 5-20 synthetic, and a swap to a HVH tapered combo spacer helped power even more, allowing this "lowly" 318 to tag 415 hp. That's not a bad number for a simple and dirt cheap street combination, and more than we've seen some bigger street builds make.[/font][/font][/font]
[FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][/font][/font][/font]
[FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif']Hollywood Steve "Stevie" Brule added a set of 1.6:1 aluminum rockers, and even set at zero lash, the rpm capability crashed. We had as much spring as we were willing to run on the street, so this is a dead player with the high-velocity cam, at least without serious attention to lightening the valvetrain. Some 8mm or hollow-stem valves, Ti. Retainers, and beehive springs may have allowed the hydraulic lifters to cope.[/font][/font][/font][/font]
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[FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif'][FONT='Times New Roman','serif']Legend
Base: Baseline Combo: ThermoQuad Carb
Demon: Switch to 750 Mighty Demon Carb on 1" spacer
Lube: Switch from 20/50 mineral oil to 2/20 Lucas synthetic
Taper: Switch from 1" open to HVH 1" tapered spacer
Rock: Switch from 1.5:1 factory valvetrain to aluminum 1.6:1 roller rockers

*Exhaust tested with flow tube
[FONT='Times New Roman','serif']http://www.moparmusclemagazine.com/techarticles/mopp_0409_318_engine_build/
[FONT='Times New Roman','serif']If you want 300hp out of your 318 this will get you there: Bowl port the heads and have the valves back-cut 30*, Edelbrock RPM intake(Airgap is more money and the rpm and rpm airgap are basicly the same), Any 600cfm carb, Comp 20-309-4, Headers and dual exhaust. This combo will give you great bottom end and will make 300hp.

The cam, intake and carb alone will not get you there, you need more head flow. So bowl port the heads, or install some 360 heads.[/font]
[FONT='Times New Roman','serif']Iam in the same boat with my 318 in a 75 Plymouth Scamp. I have a mild cam, medium rise intake, 600 cfm holley, dual exhaust and 3:55 gears. ITS A DOG! Do the 360 heads bolt on and will they bring this motor to life! This is a 140 HP motor stock and its hard to beleive 300 HP from this set up. HELP [/font]
[FONT='Times New Roman','serif']try finding heads and intake from 1989-1992 318 or 360, as these are better heads ,better combustion(heart shaped chambers) and will increase compression a bit also. also i think that a mild cam with these heads shaved.020to .030 and the intake shaved to match will give you the power[/font]
[FONT='Times New Roman','serif']The 80's and early 90's 360 were not and never will be a heart shaped chamber. They are open, just like every other non magnum 360 head. This is fact.

The 309 cam has a 268/276 duration and a .464" lift. Its a great cam for the street. [/font]
[FONT='Times New Roman','serif']http://forums.moparmusclemagazine.com/70/6387479/general-mopar-discussion/budget-318-build/index.html[/font]
[FONT='Times New Roman','serif']http://www.dynamic-pc.com/mopar/links.php[/font]
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[greymouser7]

[FONT='Times New Roman','serif']Chrysler Small Block Cylinder Heads:
Casting Differences and Porting [/font]

by Paul M. Pitcher[FONT='Times New Roman','serif'][/font]

[FONT='Times New Roman','serif']Introduction:[/font]

[FONT='Times New Roman','serif']This report will compare several modern small block Chrysler heads with those used on the earliest LA blocks and in 340 High Performance applications. Chamber configurations and volumes, valve sizes, and port volumes will be compared. Some aspects of porting the modern heads will also be covered. The sources for information contained in this report are my observations; Larry Shepard's book called "How to Hot Rod Small Block Mopar Engines", published by HPBooks (1989); "How to Build Dodge and Plymouth Performance", edited by Larry Schreib and published by SA Design (1991); and the "Mopar Engines" book, 8th edition, also written by Larry Shepard. The SA Design book highlights the work of Bob Mullen, one of the principal designers of the W2 cylinder head. [/font]
Rebuilding the Chrysler LA engine offers some interesting choices in modern cylinder heads and performance manifolds. Probably the biggest incentive to consider using modern heads is the presence of hardened exhaust valve seats, enabling the use of unleaded fuel without appreciable erosion of the exhaust valve seat. Induction hardening of exhaust valve seats was begun in the early 70s. In addition, the latest heads were designed to optimize combustion to enhance fuel economy. These so-called "swirl port" heads were introduced sometime during the 1985 model year, and were probably offered in versions for 318-2bbl, 318-4bbl, and 360 (truck) applications. Donor cars for these are becoming plentiful in the salvage yards, and with the information contained in this report, the reader can make some informed choices.
A few words on condition are warranted. Sometimes, heads found on junkyard cars are cracked. Cracks typically form in the area between the valve seats as a result of engine overheating. Therefore, fleet vehicles which have been abused in city driving (like taxis) may not make the best donor vehicles for cylinder heads. Often valves in used heads are reusable. Check the flatness of the end of valve stems as a crude indication of the amount of wear on the valve. Heavy carbon deposits in the exhaust ports are an indication that the engine was running rich, so the likelihood of burned valve seats due to an excessively lean air- fuel mixture might be lower. My observation is that considerable variation in chamber volume can be expected, especially in later castings, which tend to be of lower quality than earlier ones. Differences of one or even two cubic centimeters (ccs) between chamber volumes in the same head can be seen in later heads. Since it is recommended that chambers vary no more than 0.3 cc, it is advisable to check chamber volumes and consider equalizing them before planned machine work is started. Often it is a single chamber that is unequal to the rest. Another indication of casting quality is the surface texture in the chamber, which is much rougher in later castings. Finally, casting or machining defects are sometimes seen. If the holes for valve cover bolts are not jigged accurately, the drill can penetrate into the intake port, resulting in a potential vacuum leak that should be welded shut.
[FONT='Times New Roman','serif']The Heads:[/font]

Production heads used on 1964-66 LA engines have closed chambers 57-65 cubic centimeters (cc) in volume. The pair I examined had chamber volumes averaging 64.5 cc. Exhaust ports average 60cc in volume and intake ports average 127cc in volume. The valves are 1.78 inches in diameter (intake) and 1.50 inches in diameter (exhaust).
For 1971 and 1972, 340 and 360 engines were equipped with 3418915 heads, so-called "J" heads, because of the cast-in J in three locations (backwards in one place) on each head. These were either equipped with 1.88 inch/1.60 inch valves, or 2.02 inch/1.60 inch valves, and have "open" chambers with volumes of 65-73 cc. Open chambers have a circular margin. The heads I examined had the larger valves and an average chamber volume of 71 cc. The ports are large, averaging 69 cc (exhaust) and 149 cc (intake).
Police sedans were equipped with a high performance 318 engine, which was equipped with 360 heads and a 4 barrel carburetor (Thermoquad through 1984, Quadrajet from 1985). The earlier ('80- '84) heads have a 4027596 casting number and a cast-in "360" on the top of an intake runner. It has an open combustion chamber with a volume of between 66 and 72.5 cc. The pair of heads I measured averaged 71 cc. The valves are 1.88 inch/1.60 inch and the ports are large, averaging 65cc on the exhaust side and 149cc on the intake side. Note how similar the volumes of these heads are compared to the performance heads of the early 1970s. Police engines are equipped with flat top pistons with no valve relief's. Calculated compression ratio is 8.4:1.
Beginning in 1985, police sedans were equipped with a different 360 head, 4323345, with larger pushrod holes, 11/16 inch in diameter, instead of 1/2 inch as found on all earlier heads. The larger pushrod holes are to accommodate hydraulic roller lifters, which were introduced in 1985. The chamber is open and its volume is slightly larger than the earlier 360 heads, 69 to 77 cc. The two heads I measured averaged 74 cc. Port sizes are very similar to earlier heads, and the larger pushrod hole does not narrow the intake port relative to the earlier heads. These heads also have 1.88 inch/1.60 inch valves. Because the piston pin height is 0.020 inches greater, the calculated compression ratio is similar to earlier engines, even though the chambers are larger. It has been suggested that the 345 heads are a swirl port design, but the port and chamber shape is indistinguishable from earlier heads.
It may be problematic to use the 345 head on certain early applications because of the large combustion chamber. In order to preserve the compression ratio, excessive amounts may need to be planed off the deck surface of the head or off the block deck. For any open chamber head, the chamber volume is reduced about 0.2 cc for each 0.001 inch planed off the deck surface of the head. If more than 0.010 inch is removed from the deck surface, the intake surface will need to be milled to allow the intake manifold to fit. Mill 0.0095 inch from the intake surface for each 0.010 inch milled off the deck surface of the head.
The 318-2bbl heads (4323302) used from 1985 on are a swirl port design with a closed (heart-shaped) combustion chamber design with a chamber volume of between 56 and 65 cc. The 4 heads I examined averaged 62cc in volume. The 302 head has 1.78 inch/1.50 inch valves and small ports averaging 54cc on the exhaust side and 118cc on the intake side. The intake ports have a more severe dogleg than earlier heads because the holes for the pushrods are larger - 11/16 inches. Cars equipped with the 302 head have a dished piston to keep the compression ratio from being too high. Some cars left the factory with nail head exhaust valves in 302 heads, others with semi-tulip exhaust valves, which add 0.6-0.75 cc to the chamber volume. There is an interesting excerpt in "Mopar Engines", page 72, describing how such a head was ported and made to flow as well or better than other small block cylinder heads. Apparently, this experimentation resulted in the master for today's Mopar Performance P4452758 cylinder head.

Table 1. Chrysler Small Block Cylinder Head Volumes (cc) [FONT='Times New Roman','serif'][/font]

[FONT='Times New Roman','serif'] [/font]

Casting Number[FONT='Times New Roman','serif'][/font]
Year[FONT='Times New Roman','serif'][/font]
Chamber[FONT='Times New Roman','serif'] [/font]
Exhaust[FONT='Times New Roman','serif']
Port [/font]
Intake[FONT='Times New Roman','serif']
Port[/font]
[FONT='Times New Roman','serif']2465315 / 2658920[/font]
[FONT='Times New Roman','serif']1965-1966 [/font]
[FONT='Times New Roman','serif']64.5[/font]
[FONT='Times New Roman','serif']60[/font]
[FONT='Times New Roman','serif']127[/font]
[FONT='Times New Roman','serif']3418915[/font]
[FONT='Times New Roman','serif']1971-1972 [/font]
[FONT='Times New Roman','serif']71[/font]
[FONT='Times New Roman','serif']69[/font]
[FONT='Times New Roman','serif']149[/font]
[FONT='Times New Roman','serif']4027596[/font]
[FONT='Times New Roman','serif']1980-1984 [/font]
[FONT='Times New Roman','serif']71[/font]
[FONT='Times New Roman','serif']65[/font]
[FONT='Times New Roman','serif']149[/font]
[FONT='Times New Roman','serif']4323345[/font]
[FONT='Times New Roman','serif']1985 --> [/font]
[FONT='Times New Roman','serif']74[/font]
[FONT='Times New Roman','serif']62[/font]
[FONT='Times New Roman','serif']150[/font]
[FONT='Times New Roman','serif']4323302[/font]
[FONT='Times New Roman','serif']1985 --> [/font]
[FONT='Times New Roman','serif']62[/font]
[FONT='Times New Roman','serif']54[/font]
[FONT='Times New Roman','serif']118[/font]

[FONT='Times New Roman','serif']Porting Small Block Heads:[/font]

The impetus to consider modifications to the ports of modern small block heads comes from the need to match performance manifolds to them. As a footnote, it is interesting that production exhaust manifolds on 1985 and newer M bodies (Diplomat/Gran Fury) have openings that are similar in size to the 340 HP manifolds of '68- '70 or '71. Thus, when these or 340 HP exhaust manifolds are mated to the 4323302 heads, a huge "step" exists at the transition between the head and the exhaust manifold.
Other performance-enhancing modifications besides port-matching manifolds include 1) removing the "steps" at the transition between the valve seat and the combustion chamber and at the transition between the valve seat and bowl, 2) smoothing the transition between the exhaust bowl and runner, and 3) polishing the exhaust bowl and runner. Each of these modifications will be described. A cautionary note is in order: modifications to the port configuration will not necessarily result in performance gains. Unless the home-porter has access to a flow bench for evaluation of modifications, attempts to extensively modify the port configuration should be avoided. Instead, simple line-of-sight smoothing and removal of gross obstructions to flow should be the objective. Keep in mind the direction of gas flow and consider inertia of the flowing gas as cuts are planned. That said, for intake ports, bigger is generally better.
One other easily solved problem arises when mating modern heads to early applications. That is the air injection port present on the late heads. Simply tap this opening with a 1/4 inch-20 NC tap and thread in a socket-head set screw to plug it.
[FONT='Times New Roman','serif']Materials:[/font]

The equipment needed by the home-porter is readily available and not prohibitive in cost. A pneumatic die grinder is essential. The "mini" designs, such as Ingersoll-Rand 307A offer greater maneuverability and control. Die grinders consume a lot of air, and a higher capacity air compressor is desirable. A selection of carbide burrs is required. The most useful configurations are: 3/8 inch cylindrical, 3/8 inch round nose, taper nose, 3/8 inch ball, and 1/4 inch round nose. One bit of each type is sufficient to do several heads. Sandpaper "tootsie rolls" are also needed to polish the ports after cutting is completed. These are offered in taper and straight cylindrical shapes. About 15 each coarse and fine grade taper rolls and 5 of each grade straight rolls are needed for each pair of heads. A mandrel is needed to mount the rolls in the grinder. Good lighting is essential. A dust mask and goggles are recommended as safety equipment. The total cost of this equipment is between $100 and $200.
[FONT='Times New Roman','serif']Porting Procedure:[/font]

Before investing many hours in grinding and polishing, take the heads to a machine shop for cleaning and magnafluxing to detect cracks. It makes no sense to invest a lot of time on a cracked head, unless you're just doing it for practice. If you end up with a cracked head, don't just scrap it, have it sliced up with a power hack saw through the ports so that you can observe the thickness of the walls in critical locations.
The first procedure for the uninitiated should be to remove casting flash on the outside of each head to be modified. This will provide the porter with familiarity with the equipment and its characteristics. Use the 3/8 inch cylindrical burr exclusively for this procedure, and save the wear on the other burrs. It will take between 1 and 2 hours to remove all the flash, including the flash adjacent to the pushrod holes, at the "window" between the rocker gear side and the block side of the head. There are 3 rules in using a die grinder: 1) use two hands on the grinder at all times, 2) keep it moving to avoid gouging the metal, and 3) take light cuts at high RPM for the smoothest surface texture and best control. Be aware that using the end of the cutter can result in the grinder spinning out of control and damaging a valve seat, for example.
Next, the manifolds to be used should be matched to the port openings of the head. First, clean up the openings on the manifolds, simply straightening the edges of the openings and removing minor casting flash. Then bolt up the manifolds to the heads. Two bolts in each manifold-head junction are sufficient. To port match the heads to the manifolds, you'll need a shop vacuum sweeper, duct tape, and a can of spray paint. The procedure described here is an easier substitute for traditional gasket matching. Tape off each valve seat, except the one for the port to be marked. Wrap duct tape around the nozzle of the vacuum sweeper as a sort of gasket so that the nozzle will seal well to to the valve seat of the port to be marked. Now, turn on the vacuum, place the nozzle in the valve seat, and when flow is established, spritz some spray paint in either the exhaust outlet, or the carb mounting flange. Just a 2 or 3 second burst is sufficient. Proceed to mark all 16 ports the same way. Let the paint set for a few minutes, then unbolt everything. You should see nice, clear impressions of the inside edge of each manifold opening around each port opening on the head. You should also see that the "roof" of each port will not need to be cut very much at all to match it to the manifold.
To port match the head, simply cut to this line of paint. Now, blend back into each port about an inch to create a smooth transition between the port opening and the port runner. Use the 3/8 inch round nose cutter for this job. Do not be concerned about the large amount of metal that needs to be removed from the lower edge of the exhaust ports. However, do not try to create a straight line from port opening to the valve seat. It is likely that the water jacket will be cut into if this is attempted. Chrysler small block heads do not flow exhaust gas particularly well, due to a retrograde flow along the floor of the exhaust ports. This "riptide" sets up turbulence in the port and impedes flow. To minimize this phenomenon, leave as much metal as possible on the floor of the exhaust ports, particularly about 1 inch in from the exhaust manifold mounting flange. This will create a sort of dam which will help prevent the retrograde flow. When the experts modify small block heads for maximum performance, some metal may even be added in this area by brazing.
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There are several obstructions present in the ports which can be dealt with to varying degrees. On the intake side, there is a bump in the roof of each port near the opening. This is a cast-in boss for one of the valve cover bolts. It can be completely removed without problems unless the bolt holes are inaccurately drilled. If the holes are not centered over the web between adjacent intake ports, it is likely that the hole will be penetrated attempts are made to completely remove the boss. There is a "dog-leg" in the intake ports resulting from the pushrod hole. The wall of this obstruction is only about 1/8 inch thick on the '85 up heads, so it cannot be completely removed. However, some of it can be cut off to widen the port at this point. Do not be too aggressive, and eyeball the pushrod hole to get an idea of where you are. On earlier heads with the small pushrod hole, more of this obstruction can be safely ground off. For intake ports, the floor is critical to flow. Take care to clean casting defects from this area and the walls. Do not polish intake ports, the roughness helps to keep gasoline vapor in suspension by creating turbulence. On the exhaust side, there is a bump in the roof of each port. Do NOT try to remove this obstruction completely, or the water jacket will be penetrated. Similar to the intake dogleg, however, some metal can be removed from the highest point of this bump to make the exhaust port taller. Do not be too aggressive here either. Now that you've spent 8-10 hours on the grinder, you're developing some real skill in controlling it. You're ready to start cutting in the bowls themselves. This is the touchiest part of home- porting because of the supreme control and concentration needed to avoid gouging a valve seat and ruining the head. Make sure the burr is fully inserted PAST the valve seat before powering up the grinder. In other words, do not try to pass a spinning burr through the valve seat opening. [/font]
There are several areas that need cutting in the bowls and chamber. The heaviest cutting is to be done at the sides of the exhaust bowls, where they transition into the runners. First, feel the transition at the inside edges of the two exhaust bowls nearest the center of the head. If you were to cut the head in two, making two halves with two chambers on each half, the areas referred to here would be immediately adjacent to that cut. Compare the feel of these ideal profiles to the transition between bowl and runner in the rest of the the bowls. Feel the difference? The rest of the bowls have rather large bumps at this transition which may or may not be removed, using any burr with a round nose. My opinion is that these bumps represent obstructions to exhaust flow and should be removed, but this opinion is NOT based on flow bench results. Next, spend some time in the intake bowls with the 3/8 inch ball burr to remove edges where the valve guide was machined. Do NOT try to remove this obstruction, just round the corners off.
Probably the greatest single improvement to flow that can be made is to cut off the parting line that runs through each bowl. This parting line is parallel to the deck surface of the head, and is present at the transition between valve seat and bowl. There is a prominent corner where the outside edge of the exhaust valve seat transitions directly into the floor of the exhaust port. Cut this back so that the profile is a smooth curve. Not much metal is to be removed, but removal of this corner is one of the most important things you can do to improve the flow characteristics of small block Chrysler heads. Be VERY careful to not damage the valve seat during this procedure. The cylindrical burrs or the taper nose burr work best for this cut.
The final cut to be made is the most dangerous to the valve seats, and should be reserved until the porter's skills are maximized and NOT be tried at the end of a long day. A tiny amount of metal is removed in this cut, so fine control of the cutter is essential. The cut is made to remove the step that exists between the valve seat and the chamber itself. Some heads have very little metal to be removed in this area, other heads have a 0.040 inch to 0.050 inch step. The step is most detrimental to flow in the shrouded areas of the valve (302 heads). Use the taper or 1/4 inch round nose burr for this cut and do not try to remove the entire step with the cutter, come back with a sandpaper roll to take off the last few thousandths and finish the surface. During this cut, smooth the vertical parting line which exists at the front and back edge of each chamber. In high performance applications with radical cams, it may not be advantageous to remove this step from the intake side, because it restricts flow at low valve lift which is beneficial. If there is some restriction of flow at low valve lifts, intake charge velocity and inertial filling will be greater as the intake valve continues to lift, resulting in a greater intake charge overall. Since CFM is very small at low valve lifts, a change in flow at this point has a smaller potential effect on the total intake charge than a change in inertial filling at higher valve lifts.
OK, now the cutting has been completed, you're ready to switch over to sandpaper rolls to finish the surfaces. Start with the exhaust port runners to get a feel for how the grinder behaves. Use a coarse cylindrical roll to finish roof, floor, and sides, and a coarse taper roll to finish the corners of each exhaust port runner. You can do some slight smoothing of the intake port at the port opening, just to take off your mill marks from the previous cutting. Proceed to finishing the exhaust bowls, using taper rolls, or cylindrical rolls that have a round end as a result of use in the runners. Take off enough metal to completely remove the cast texture from the mold. Watch the valve seat as you polish to give the best avoidance of contact of the sandpaper rolls with the valve seats. After you've done everything with coarse paper, switch to fine and start over. Expect to spend almost as much time polishing as was spent cutting.
The last thing to be polished is the transition between the valve seat and the chamber. You won't be able to polish in the shrouded areas of the chamber, but try to take off mill marks from previous cutting in the rest of the chamber, and take off any sharp corners that may exist. The margin of each chamber can be rounded off slightly to prevent hot spots and preignition.
OK, now that you are finished porting, all that remains is to have the valve seats ground. The three-angle valve job is a standard in performance heads. You might need to come back with sandpaper rolls and remove any edges that arise from the seat grinding procedure, but for all intents and purposes, you're ready to hit the streets and kick some Brand X butt! The beauty of this procedure is that it is completely unapparent unless the engine is torn down. The Mopar Engines book says that the home porter can expect improvements from 5-10 HP, but that the potential exists to get 50 additional HP out of the 302 heads!
Paul's original document date unknown, (perhaps 2000). This document was originally linked to his Web site, which apparently went offline in early to mid 2003.

[greymouser7]

hope that helps- this is some of the research i have pulled from the web for my rebuild-john m anderson

[greymouser7]

The 318-2bbl heads (4323302) used from 1985 on are a swirl port design with a closed (heart-shaped) combustion chamber design with a chamber volume of between 56 and 65 cc. The 4 heads I examined averaged 62cc in volume. The 302 head has 1.78 inch/1.50 inch valves and small ports averaging 54cc on the exhaust side and 118cc on the intake side. The intake ports have a more severe dogleg than earlier heads because the holes for the pushrods are larger - 11/16 inches. Cars equipped with the 302 head have a dished piston to keep the compression ratio from being too high. Some cars left the factory with nail head exhaust valves in 302 heads, others with semi-tulip exhaust valves, which add 0.6-0.75 cc to the chamber volume. There is an interesting excerpt in "Mopar Engines", page 72, describing how such a head was ported and made to flow as well or better than other small block cylinder heads. Apparently, this experimentation resulted in the master for today's Mopar Performance P4452758 cylinder head.