305 Bad Mouthing

[305 H.O.]

I have an 86 camaro with a 305. I had a 82 camaro with a 305 and a 350. It got stollen after i put the 350 in it. My 305 was faster except for on take off. The camaro i have now has 3.23 gear ratio, possi rear end, 700r4 trans with a shift kit, a 2300 stall and a stock 305 h motor. 2.0 60 foot time and an et of 9.48 at 76mph. 8th mile. I have out ran numours 350's with both of my 305's on bottom end and top end. you just got to know how to tweek them. one of the motor adjust ments i made was a little bigger carb and advanced the timming and that made a big big difference in how the car ran.

[ACE TECH]

you are sadly mistaken if you think it is cheaper to build up a 305 in fact it is more expensive because parts arent as widely made and sold for the 305.
and it isnt just the bore that is different the heads are different and the 305 blocks arent as strong.
but whatever you say buddy.

[dxrflyboy]

I have to take issue with a few things here. First of all, since the 350 is bigger than the 305, it will make more power. The 305 will only outrun a 350 if it is built and tuned better. Also, if the 350 breaks the tires loose and the 305 doesn't, the 305 has the advantage on takeoff. If you replace a 305 with a 350 and put the 305 intake and exhaust on it, it won't be able to breathe and won't make much more power than the 305 did.

I also don't believe 305s cost more to build than 350s. For one thing, cores are cheaper since most would rather have a 350. Jeg's sells World Torquer S/R heads for 305s for about $10 LESS than for 350/400 heads. It's not a big difference, but blows away the theory that it costs more to build a 305. When you consider how many crappy 350 heads there are out there (882/624 castings) that are basically disposable, it makes sense most of the time to get a set of these heads anyway. 305s and 350s used the same cranks and rods, so the only difference is the pistons. The difference in price for a set of flat topped pistons is slight between the 305 and 350. Forget about finding a set of 12.5:1 pistons for your 305, but I'm talking street motors here. Add to the fact that there are plenty of healthy 305 bottom ends out there already in cars people drive every day that just need to breathe a little better to make power, and you have some very good reasons to pump up your 305 a bit instead of going through the trouble and expense of building a 350. Sure, if you already have a 350 to build, go for it! I did, back before aftermarket iron was readily available and the 350 had good factory heads (1971). But there's no reason to give up on your 305. It can make power too. 13-second ETs aren't uncommon for built 305s in 3rd gen F-bodies.

I'll grant you that 305s don't have the beefy main webs that big bore smallblocks have. Ultimately, that will limit the power they can produce. But this will probably never be a factor in a street engine. If you're concerned about how strong your 305's bottom end is, you're probably going to build something bigger anyway. I'll qualify my statements here by saying that pumping up your 305 for the street makes sense, but building a race 305, in most cases, doesn't. That doesn't mean 305 blocks are weak. In fact, they have thicker, not thinner, cylinder walls than 350s. 350 walls are thin in between the cylinders, and are more likely to be unusable due to core shift than 305s. As GM's quality control has gone down the toilet over the past 2 decades in favor of corporate profits (or reduced losses thanks to a weak economy and consumers getting sick of buying junk), this has become more and more of a problem. Engines that never should have made it through the machining process wound up in cars and trucks with head bolts that weren't even tight! I had an '87 Chevy K10 come into the shop where I worked with a blown head gasket and one head bolt halfway tightened but bound up thanks to crooked threads in the block due to core shift. That block should never have made it past the machining process, but profit margins prevailed, the engine was assembled, dropped into the truck on the assembly line, and Chevy rolled the dice, hoping it would make it past the warranty period, Unfortunately, it did. I'm just venting here, but it just goes to show you that while 305 blocks may be weaker on the bottom than 350/400s, they do have a bit more meat where it counts for a street motor.

Dan

[comp]

305 is a good relieable engine ... i'm going to stroke one to act like a
diesel (crank out of a 400) they can't breath because of the bore &
the available flow. mine is going to work from 800- 3000 RPM's

[dxrflyboy]

A set of S/R Torquer 305 heads will help it breathe better. If you're putting a 400 crank in it, the motor will need all the flow help it can get! The S/R Torquer 305 heads have 1.94/1.5 valves like basic 350/400 heads. Figure in the cost of new guides, a good 3-angle valve job, and resurfacing on the stock heads, and you will probably find a new set of heads a worthwile investment. If the stock heads need any more than that (like new seats), you might as well throw them away. Recycle them as raw iron for casting a good set of heads!

Dan

[quaddriver]

who told you guys that 305s have windowed mains? no SBCs have windowed mains (it is too small and too soft to lose critical strength here), and other than variations in the bearing saddle size (pre 68, post 68, 400) the bulkheads are the same. It can be truthfully said that no 305 was ever made with 4 bolt main caps, but then again, a few other bores never have also and its more likely you will bust a rod cap/bolt long before you ever lose a main cap. the stock chevy bottom end will hold 500hp with no changes. 305s on a blower will generally be south of 400hp so it should be no concern

[dxrflyboy]

I don't think anyone said anything about "windowed" main webs. That's an Oldsmobile thing. I'll grant you that I'm not sure of the main web thickness on small bore smallblocks and whether or not they can be machined for 4-bolt mains. But I doubt anyone is going to build a 305 that will need them! I believe the advantage of 4-bolt main caps is more rigidity under extreme load conditions. 2-bolt caps concentrate stress on the block at 2 points on each main, right around the journal. 4-bolt caps spread this stress outward.

I did say that 305s have THICKER cylinder walls than 350s, thanks to the smaller bore allowing more meat in between the cylinders. The most unusual smallblock is the 400, which has SIAMESED cylinders (cast together with no space for coolant to run between them and "steam holes" in the block and heads to vent hot coolant trapped where the cylinders run together.

Dan

[hvyrghtfoot]

I will probalby switch out motors whenever the bottom end of my 305 drops out, but until then I would love to find a good intake manifold for my 89 brougham LS. I looked at Edlebrocks Performer TBI, but at the end of the description it says "will not fit Caprice" is it a clearance problem?

If anyone knows where I can track down some performance parts for my sleepy 305 , please let me know.

[volz1fsu]

I think that the only problem with the Edelbrock manifold for the Caprice is Hood Clearance. I could be wrong though, maybe the cowl sticks out too far off the firewall and that could cause problems. Anyways, here is a website that will almost tell all the things that you could do to a 305 to pep it up. http://www.goingfaster.com/spo/modthel03.html

[quaddriver]

Originally Posted by hvyrghtfoot

I will probalby switch out motors whenever the bottom end of my 305 drops out, but until then I would love to find a good intake manifold for my 89 brougham LS. I looked at Edlebrocks Performer TBI, but at the end of the description it says "will not fit Caprice" is it a clearance problem?

If anyone knows where I can track down some performance parts for my sleepy 305 , please let me know.

yes hood clearance is a bugger. the performer is I think 3/4-1" taller

[dxrflyboy]

I could see the high rise intake creating a clearance problem on a '91-up Caprice, but I have my doubts it will create a problem in your '89. Most of the "boxy" Caprices were carbureted. Only a few years were TBI. This may be why Edelbrock says their intake won't fit the Caprice. You may want to contact Edelbrock to verify this.