Which cam and pistons to choose???

[NOVA71]

OK, I've got to pick a cam and pistons for my engine, so I just figured I'd see if anyone on here has any cam recommendations, or other recommendations for building a solid street engine (in particular MrPbody).

The vehicle is a 71 Nova weighing in at around 3100 lbs with a 350 chevy engine, TH350 tranny (with shift kit) and 3:42 geared posi rear with I think around 26 inch tall tires (225 60 R 15 on all fours). This is a street car, so it needs to have good street manners and reliability. I would like to make the occasional pass or two at the dragstrip, so I don't want the engine to run out of juice at around 4000 rpm either (like the present engine).

OK, what I've got for the 350 so far: New Speed Demon 650 vac. sec. carb, Dart Koolcan aluminum intake (Dart's version of the Edelbrock RPM Airgap), Chevy Bowtie 64 cc cast iron heads with 2.02/1.60 valves and full roller rockers (I think they are Crane) and pushrod guideplates, Edelbrock aluminum water pump, GM Heavy Duty electronic ignition control (Made by MSD, it's their 6A unit with the GM stickers on it), an older set of (but still good) Hooker full length 1 3/4" tube headers, 2 1/2 inch duals feeding into Flowmasters (I think they are 40 series) and 3" turndowns dumping in front of the rear end.

I have a low miles 1975 350 bottom end with cast crank and cast pistons. I would like to get close to 400 HP and 400+ ftlbs of torque. My questions are if it checks out fine, should I just bolt my parts on it and run it as is, or should I bore it to clean it up and upgrade to forged or hyperutetic pistons? Do I really need better pistons or would the cast ones hold up fine? I will get new pistons if it means having a reliable engine making that much extra power. Would I need to port my somewhat out dated heads (I know that they were one of the best heads 20+ years ago) or is it really worth the cash to port them? I am going to port match them to the intake regardless. What compression ratio would be the max for a street car (9.5 to 1?)? And what cam would best suit this combo and make close to that kind of power? I was thinking of going with either the Comp Cams Xtreme Energy 262H (part#12-238-2 [email protected] 218 224 and lift .462 .469 lobe 110) or the 268H (part#12-242-2 [email protected] 224 230 and lift of.477 .480 lobe 110), or the Comp Cams Magnum 270H (part#12-211-2 [email protected] 224 224 and lift of .470 .470 lobe 110) but I'm no expert here. I wanted to stick with a hydrualic cam. I know rollers are much better but they are so expensive. Also, I will be buying the complete cam kit so that I get the new timing chain and matching valve springs, and all other related hardware.

Please give me any recommendations you have. Thanks in advance!

[MrPbody]

To get to your goal of 400 horsepower, you will need to upgrade to the flat top pistons. If you MEVER intend to spray nitrous to it, Speed Pro H345NCPxxx will do nicely. If you DO want to spray it, L2256Fxxx is a better choice. This is the old "TRW" type. Rather heavy, but very tough.

I would recommend boring and honing with a deck plate. Balance is also necessary. Rods should be resized and ARP bolts used.

For your power goal, XE274H would be the cam I would choose. It's a bit on the "rowdy" side (lopes), but has good "manners" and works well with 9.5:1. Better than ANY of the old Magnum grinds.

Jim

[NOVA71]

So, the Speedpro hyper flat tops for pistons (I was kinda thinking they would probably be a good choice). She will probably never see nitros anyway. As for the XE274H cam, would I need a higher stall torque converter or could I get away with a stock one? Also, would I still have good vaccuum for my brakes and accessories? I was thinking of going with the XE268H but Comp Cams recommened the Magnum 270H. I was still thinking that the 268 was a better choice though. You don't think the 274 would be a bit much for street use? I only plan on building this engine once (unlike some of my buddies) and I want to get it right the first time. Anyhow, thanks for you input. I've read quite a few of your posts and you seem like you know alot. Please feel free to leave me any more recommendations. Thanks again.
Darren

[MrPbody]

Darren,

Inventories of Magnum cams have not moved much since the XE series was introduced. This is a possible reason for getting recommendations for them. In my experience, not much is in the "league" of the XE series.

Yes, XE274H would need a 2,400 stall converter. The "book" says XE268H is the largest for "stock converter". We've seen more like XE262H being the largest one, as some of the BBC cars with XE268H are a bit "doggy" until they get moving. Still, XE274H is our biggest seller, regardless of engine family.

Jim

[68elco]

I have a similar question, Ive got a 327 that im getting rebuilt with an 11 to 1 compression ratio (thats stock) im looking at the comp cams extreme energy 274 with solids, my question is how much will this new cam effect my vacuum, all ive got is power disc drakes no power stearing

[MrPbody]

68elco,

We built a 327 last year using XS274S. It idles similar to a 327 with the old Duntov 30-30 in it, but makes lots more low-end. Good vacuum signal. We use a similar grind in a lot of Pontiac 461s for street. It will be fine for your brakes.

You are aware, if you really have 11:1 compression, "pump gas" (93) won't be good enough. You WILL damage your engine from detonation if you don't use higher octane. I would recommend rather, you lower the compression to the 9.5:1 range. The XE series of cams work VERY well in lower compression environments. You could actually drive the thing somewhere!

FWIW, the 327 we built last year with that cam, keeps tearing transmissions out ('64 Impala, 4-speed). The car is a beast, even with the little small block! (9.5:1)

Jim

[68elco]

thanx Jim thats good to know the 327 is for a 68 el camino that has a muncie m-21 this is my daily driver ive looked on the internet and researched my numbers and have found that it is a 325hp w/ 11 to 1, the car is numbers matching and im hesitant to change the stock internals im lookin to get 375-400 hp out of this engine is the 274 a streetable cam? also can i get that much hp out of the 268 ive got 2.02 cammel humps(ive measured the valves myself) rebuilt q-jet im going to upgrade to an edelbrock manifod, headers of course and at this point im mulling over 10-1 or 11-1 compression
thanks alot
-morgan

[MrPbody]

What is a 268? Is that a .030 over 262? If so, forget it. No performance value to that little engine. A 283 is far superior.

9.5:1 is considered the highest compression ratio for "pump gas" (93 octane). XE274H is a great street cam. Fuel economy is NOT it's purpose.

For the smaller engines (<350 CID), Edelbrock Performer is the intake of chioice, unless you're RPM range is to exceed 7,000. Then you want Performer RPM.

Jim

[NOVA71]

I think he meant the xe268 cam.

I got the Desktop dyno program (it's pretty cool) and I plugged in your specs for a 327 bored 0.30 with camel humps (casting #462 if that's the ones you have) with 62 cc chambers 2.02/1.60 valves, 10-1 compression, dual plane intake, 4bbl 750 cfm carb, large tube headers and mufflers, and the xe268 solid cam. That gave 379HP@5500rpm and 408ftlbs@4000rpm. The same specs with the xe274 solid cam gave 388HP@5500rpm and 406ftlbs@4000rpm. Just for the hell of it I dropped the compression down to 9.5-1 and the result was only a loss of about 8-10HP and 6-7ftlbs. Probably worth the slight loss to enhance drivability on pump gas.

This leads me to another question. While I was checking these numbers, I noticed that switching from a hydraulic cam to a solid cam was worth about an additional 20-25HP and 15-20ftlbs. I know they say that the solid cams require some routine adjustments, but would I have to adjust them that much if I am using full roller rockers with locking nuts? Also, how often would I have adjust them?

Darren

[68elco]

I was talking about the xe268s not a 262 bored .30 over but any ways ive decided to go with 9.5 compression, thanks for all the advice jim and darren
and about your solid lifter Q darren i was talking to the guy who is rebuilding my engine and he said to check it after the first 500 miles and then after that with every oil change so in my eye that is well worth more horsepower

[MrPbody]

With modern valve train components, frequent adjustments to lash is history. Have the heads modified for screw-in studs and guideplates (use 7/16" studs, NOT 3/8"). That will require rockers for 7/16" studs. Harland Sharpe rockers are about the best for the price anywhere. If the budget can handle it, use Comp "Pro Magnums" or even better, "Hi Techs". Stick with 1.5 ratio, as the little engine doesn't NEED high lift to make power.

If going to a solid flat tappet, I highly recommend Comp XS274S. We use that grind a lot in small blocks, and now have a derivative of it for Pontiacs. For a street engine, get the lifters with the "Cool Face" option (Crower's name for drilling a .012" hole in the lifter face. Gives positive lube to the lobe/lifter. Crower is not the only source, but the best known.

Jim

[68elco]

hey jim do you work for comp cams?

[MrPbody]

Nope. I work for ME. Central Virginia Machine Service in Burkeville, Virginia. I recommend what I've found to work the best, based on current trends and availability. In the past, UltraDyne was the cam company of choice. When they went "under", one guy went to Lunati and another went to Bullit. There's controversey over who REALLY has the UD grinds.

Comp has the most complete and well-sorted line of valve train components. XE cams are unsurpassed for street-level performance, and are quite efficient to boot. We've seen 396s in Chevelles going high 12s and still making 17-18 MPG. Some of the 400 Pontiacs are making that level of power and getting 20.

So, yes, I may sound like a Comp "commercial", but it comes from real-world experience with many different engine families. I sell more Comp XE274s than all other cams combined, regardless of engine family. I make more money on the generigrind cams (Edelbrock, Melling, Summit, etc.), but the engines are more important to me than the little difference in profit. XE cams make me a "hero" among many crowds.

Jim

[NOVA71]

Unfortunately I don't have a whole lot of real word experience under my belt, but I do alot of reading and I'd have to agree that Comp Cams is where it's at. They seem like they are the top dog for cams and valvetrain components. I see Crane now offers a Z series cam that is very similar in design to Comp's XE line. I ran the Z series 268 cam and the HP & torque figures were almost identical to Comp's (within a few points). I think, just for the hell of it, I'll check to see if they make a Z series that's comparable to the XE274. I'm still going to buy Comp though (probably the 274 like you recommened Jim). I may even go with a XE274 solid.

I do have a couple more questions. What are the pluses and minuses of a solid and a hydraulic. I know the hydraulics are more trouble free and quieter. And solids are require a bit of adjusting now and again, and I think they give you more accurate timing? Is this true? And how do solids perform in a street car that is driven daily in the summer. Also, you said it would require a 2400 stall converter. I do have a rebuilt TH350 with a shift kit and a 3000 stall converter in the garage that I bought some time ago. How would this work with the XE274 and how would the manners be for this combo on the street. And maybe last of all would this combo be hard on parts? I don't drive like a nut and am really pretty easy on the old girl, but I do give her a good shot every now and again when the time arises.

Thanks again for all the info,

Darren

[MrPbody]

Darren,

Solid lifters offer a bit more power due to the "positive valve action". A hydraulic lifters is a "shock absorber", used to maintain contact with the valve train parts at all times.

If you set your heads up with screw-in studs and guideplates and "poly-locks", periodic adjustments are held to a minimum.

Jim