Should I get new heads?

[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?

[billlsbird]

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

[Gerald Streeks]

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.

[BigTruckDriver]

why not a set of 58cc 350 heads?

[Gerald Streeks]

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

[southerner]

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.

[Gerald Streeks]

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.

[shawnlee28]

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.

[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.

[Gerald Streeks]

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.

[Gerald Streeks]

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

[erik erikson]

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.

[R Pope]

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.

[allengator]

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.

[erik erikson]

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?