Ford Muscle Cars Tech Forum banner

1 - 5 of 5 Posts

·
Registered
Joined
·
2 Posts
Discussion Starter #1
I am rebuilding a 69 4v 351w and I have run into a couple problems. First off, I didnt want to spend the dough and get the stock heads rebuilt (3 dif shops quoted me at "about $580" with valves and new exhaust seats) so i picked up a set of gt-40 cast iron heads,(not gt40-p) rebuilt with a valve job. 62cc combustion chamber and the springs
are set up to be used with a 94 cobra stang.

QuestionS :
1) What pistons will give me around 10 to 1 comp ratio? It has flat with 4valve relifs now and that was 10.7 :1 with stock high comp heads.
2) what cam would make the car run sweet and not knock the valves into the pistons?
3) If anyone has put these on an old carburated 351w and if so how did they help/hurt performance?

Any Input greatly aprecciated
 

·
Registered
Joined
·
6,662 Posts
I think Keith Black makes a 10:1 piston for the 351w .Your gt-40 heads have almost exactly the same size combustion chamber as the stock 351 so they should work fine as is.Its always best to check with a machine shop who's familiar with these pistons and get their input so you get the compression you want.As you mentioned the stock pistons are 10.7 so if you just install these heads you will have roughly the same compression.Do not mill the heads if you are trying to lose some compression as this would increase it!
 

·
Premium Member
Joined
·
23 Posts
I think the early 351s had a lower deck height...That might help with the c/r.
I'm there now with my four/V8 conversion
and I was going to use the early heads to bring up the c/r on my 85 short block...
I built a 351 with my friend and we had problems with c/r on a 85 351 using the GT40 heads(Not the "Ps&quot
with the "Standard" TRW
forged piston.Had heads milled .040 and still only came out with low 9 ish c/r,so be carefull!If you don't spend it on the old heads,you may end up spending it on a set of pistons to "Fix" the c/r...
 
1 - 5 of 5 Posts
Top