Thread: Should I get new heads?

Tweet

I have a 90 350 shortblock that is a rebuild from Advance Auto Parts. It has inverted dome -23cc pistons. The heads that are on it are a set of 76cc heads from a 73 truck motor. I'm running stock felpro head gaskets. I was wondering if I should get some heads with smaller combustion chambers. I was thinking of running some 305 heads because I really don't turn the motor over 5000 rpm. I heard these heads are 58cc but they don't really flow very well over 5000. What are your thoughts?

Originally Posted by Gerald Streeks

I have a 90 350 shortblock that is a rebuild from Advance Auto Parts. It has inverted dome -23cc pistons. The heads that are on it are a set of 76cc heads from a 73 truck motor. I'm running stock felpro head gaskets. I was wondering if I should get some heads with smaller combustion chambers. I was thinking of running some 305 heads because I really don't turn the motor over 5000 rpm. I heard these heads are 58cc but they don't really flow very well over 5000. What are your thoughts?

.....Hi Gerald, I went to campbellenterprises.com & used there compression ratio calculator. With the -23 inverted dome pistons, .040 gasget, .0001 deck height & 76 cc heads your compression ratio is 7:68 to 1..... & With the 58 cc heads your compression ratio is 9:00 to 1..... Not sure of advatages/disadvatages on 305 heads on your application so others will have to answer..... zzz

Not even 8-1 compression sounds like garbage to me. I just know that this 350 should have more power and I think the pistons are killing the compression.

why not a set of 58cc 350 heads?

Trying to look for an inexpensive set of rebuilt heads and I don't think 58cc 350 heads are inexpensive.

Why not keep the heads you have got and put in a set of flat top pistons, this will set your compression up as well as increase combustion efficiency by improving squish and cutting down on turbulence.

Because the motor is already in the truck and I don't have the resources to pull it out but I do have the resources to change the heads.

Are your current heads good ? They have to be worth some thing ? 305 heads would work and smoke the tires with the right cam ,the upper rpm hp will suffer the most.

The current heads were just redone with z28 springs new valve guides and seals. I just think that the 76-78cc open chamber head is killing my compression. And I don't need upper rpm I don't turn the motor over 5500 rpm. The motor is in a 73 3/4 ton truck with 31 10.50's on it.

It has a lunati voodoo cam in it: intake at .050" lift 213/219 exhaust, 256/262 advertised, .454/.468" lift, 112 LSA 1000-5500 rpm.

A professional products crosswind intake similar to edelbrock air-gap, a 600 edelbrock carb, and headers.

Originally Posted by Gerald Streeks

The current heads were just redone with z28 springs new valve guides and seals. I just think that the 76-78cc open chamber head is killing my compression. And I don't need upper rpm I don't turn the motor over 5500 rpm. The motor is in a 73 3/4 ton truck with 31 10.50's on it.

You did'nt say what gear you have.
Also you did'nt say if you had a looser stall in it.
I.M.O.,I would look at a 1,800-2,000 stall.
With that tall a tire I would put more gear in it.
Those are big tires to try and move.

I've learned the hard way, you don't want high compression in a truck engine. Stay around 9.0 or less. A light car never has to pull long, the speed increases and the engine revs up. A truck will soon overheat the chambers and start detonation, forcing a downshift.

Originally Posted by Gerald Streeks

A professional products crosswind intake similar to edelbrock air-gap, a 600 edelbrock carb, and headers.

By similar do you mean "Chinese rip-off"???
If you want hot-rodding to have a future, buy from American companies that actually do "research and development" not "receive and duplicate"...

Buy the Edelbrock.

Originally Posted by allengator

By similar do you mean "Chinese rip-off"???
If you want hot-rodding to have a future, buy from American companies that actually do "research and development" not "receive and duplicate"...

Buy the Edelbrock.

Last I knew Edelbrock did not have a copyright on their intake manifolds.
How is it a rip off?