[78mach1]

alright so i have a 306 that i built a while back that is currently in my 78 mustang II, when i built the motor i just rebuilt the stock heads and then threw on a performer intake, now its time for a little more, so i want to get another set of heads, its a street car so i dont need to go buy some afr`s or nothing, i was thinking gt-40 p heads, but they only make on kind of header for my car and they probably wouldnt work, whats different between the p heads and the normal gt-40`s?

[trueblue01]

Spark plug angle and the Ps have a smaller (59cc) combustion chamber

[insta]

WINSOR JR. & SR. Cast Iron Small Block Ford Cylinder Heads

if you want to stay with an iron head these work pretty good and you can get them used here and there for pretty cheap , keep an eye out on the other mustang forums , they pop up all the time . I have a set my self that have been worked over and and getting ready to get put on a new motor , they were on a full weight fox gt with an ecam and systemax intake , faceplated tko , and 4:10's . He went in the 12's pretty easy with that combo .

[78mach1]

alright, so right now my heads are 69cc heads, with flat tops, my compression i think is about 9:1 (correct me if im wrong)

if i went 64cc would that bump me around 10:1?.......also could i run pump gas? i live in salt lake city so we are higher altitude

[1slo5.0]

Originally Posted by 78mach1 alright, so right now my heads are 69cc heads, with flat tops, my compression i think is about 9:1 (correct me if im wrong) if i went 64cc would that bump me around 10:1?.......also could i run pump gas? i live in salt lake city so we are higher altitude

With a flat top piston and a 69cc chamber on a 306 you have roughly 8.58:1 compression. With a 64cc chamber you will be at 9.06:1 and with a 59cc chamber you will be at 9.6:1.

Personally I'd walk right by a set of Windsor Jr. iron heads and pick up a set of Trick Flow or AFR aluminum heads. You will be much happier and will pay close to the same price.