andylmusic76

the heads i have on my engine right now are 1.94" intake/ 1.50" exhaust, with 76cc chambers. these are considered low performance according to chevy.

i purchased a set of rebuilt 305 heads on ebay for a great price. these heads are 1.84" intake/ 1.50" exhaust, and it has 58cc chambers.

what i want to know is if it is worth swapping these heads. i know that it will raise my compression, but would i get ANY power gain since the heads i have now are considered low performance anyway? it seems to me the only difference is the intake and chamber size, but the exhaust is the same, so would the intake make a difference anyway?

TimAT

Any power gain from the higher compression will be very low in the HP/Torque bands. Those 305 heads just don't breathe IMHO, someone has probably built a killer engine with them but you never know.

big_G

The intake valve is smaller than the already too small 1.94, and the smaller chamber is going to shroud the intake valve, costing you even more horsies. No amount of compression will compensate for poor heads. Just my 2 cents.

andylmusic76

i also read about having it punched out for like 2.06" intake / 1.60" exhaust, and changing the valves. would it be worth doing this?

big_G

The ports are too small, and unless you open up the chamber (raises the chamber cc's, lowering compression) to unshroud the valves, your still

andylmusic76

well i may consider selling them. how much do rebuilt and milled 305 heads go for? these have not been used at all since rebuilt. there is nothing wrong with them. what would they be worth?

big_G

Dunno, try posting on a Camaro forum. G/L

dgruenke

For the cost of doing machine work on those to get any performance gains, you can get a new set of S/R heads for the same money, with better performance.

andylmusic76

so what would be a good upgrade from 76cc chambers, 1.84" intake / 1.50" exhaust heads? i would say i should spend no more than $350. what about summit's heads? any suggestions are greatly appreciated!

dgruenke

If you are looking for a low cost solution, you can either pick some up used, or rebuilt, preferably in a 64cc verson. The best bang for the buck in a new version would be the Vortec heads, but that requires switching over to a different intake manifold.

andylmusic76

yeah i just got my manifold, so i would probably stick to that. what kind of hp gains can i achieve with 64cc's or vortec heads?

dgruenke

The Vortec heads are 64cc. The extra power does not come just from the 64cc heads. It does increase power with additional compression, but the real power comes from the design and flow of the heads. Their are several forum members that have done the Vortec upgrade, and it gave them significant improvement.

If you went with a Dart or World Product 64cc head, those would also flow much better than the stock heads. You can even pick up a pair of L98 heads that were on later Corvettes. They are 58cc and aluminum.

Check out this site for some comparisons of flow data:

http://www.chevyhiperformance.com/te...ench_database/

Tim H

In the near future Im going to buy some of the 202/160, 165cc runners, 67cc heads from Summit. They are $650.
part #sum-152123

andylmusic76

i thought summit made a pair similar to those for around $320.

VegasJen

i did that a few years back with my original L-81 motor. used 305HO heads. actually worked great. for one, if they are the 305HO heads from the mid 80's they'll out flow any factory late 70's head regardless of valve or chamber size. THIS ONLY APPLIES TO THE 305HO heads.
if that is in fact what you bought, and as you said, you got a great deal on them, they would make a very nice supplement to a mild cam upgrade, i.e. 260-270* cam would be very nice.
if your goal is a mild step up in performance without breaking the bank and you don't expect to be running over any Z06's, i'd say to hell with what some others say and go for it. you WILL be surprised.

Little Mouse

1.94/1.50 valve head I believe showed up on the 283 as a
power pack head, the 1.84 intake valve is probably the same
size chevy started out with on the 265, seems to me you are
going backwards on airflow.

big_G

That's not saying much.....

andylmusic76

the thing is i don't have the original motor in my '77. i have a gm crate engine (for the most part the same specs asthe l-82 though). what i have installed now is 1.94" intake / 1.50" exhaust, 76cc)

Little Mouse

does it have the L/82 flat top pistons ? if you use a 58cc iron head
your comp. will be to high unless you are going to more cam then
I think you want to run.

andylmusic76

i'm not sure off hand. the number for them is $12514101. i installed a more radical cam in my engine already. 224*/234*. this was supposedly the biggest i could go with a th350 with a stock converter. is this enough cam to keep the compression down?