i have a 78 351 w that's bored 40 over and has only been started a few times . will gt40 p heads work on it and what is needed to do that ?
351 W Question
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Let me get a few of the guys attention that would know. @jrichker @madmike1157 @90sickfox @84Ttop
Let me get a few of the guys attention that would know. @jrichker @madmike1157 @90sickfox @84Ttop
I Bleed Ford Blue
5 Year Member
Short answer, yes they will fit. You will need the standard head changing stuff, and make sure your intake ports match the ports on the heads.
Any windsor based head will bolt onto your block, all ford small blocks from the 60's up to the 90's had a 4.38" bore spacing and used 10 head bolts per head all located in the same space. You can actually use any windsor or cleveland based head and they will bolt on. BUT, windsor engines had the water crossover and thermostat built into the intake manifold and the cleveland had them in the front cover so you would have to modify the water jacket ports on the heads if you tried to use them on on the other style blocks.
Any windsor based head will bolt onto your block, all ford small blocks from the 60's up to the 90's had a 4.38" bore spacing and used 10 head bolts per head all located in the same space. You can actually use any windsor or cleveland based head and they will bolt on. BUT, windsor engines had the water crossover and thermostat built into the intake manifold and the cleveland had them in the front cover so you would have to modify the water jacket ports on the heads if you tried to use them on on the other style blocks.
The only thing you have to be considerate of w/ the increased stroke of a 351 is the chamber size. What is the chamber size of the GT 40 head? In the history of the windsor's highest compression, a 69cc head yielded a CR of 10.7:1.
I'd imagine that a 78 windsor probably has a dished piston deep enough to eat cereal out of, so you'll want the smallest possible chamber you can get to yield a target CR of 9-9.5:1.
I'd imagine that a 78 windsor probably has a dished piston deep enough to eat cereal out of, so you'll want the smallest possible chamber you can get to yield a target CR of 9-9.5:1.
- Mar 2, 2015
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I think the head bolts are bigger for the 351. Not a huge deal but I think the holes need to be drilled out to accept bigger head bolts or studs...7/16 verses 1/2 inch.
To put 351 heads on a 302 you have to use bushings in the heads or tap the block for 1/2 inch bolts or studs.
To put 351 heads on a 302 you have to use bushings in the heads or tap the block for 1/2 inch bolts or studs.
I Bleed Ford Blue
5 Year Member
You are correct, the 351's do have larger bolts. And they make special shoulder bolts that neck down so you can put a 351 head on a 302 block.
Most aftermarket heads, including the ones from Ford racing have the larger 1/2" holes, and modern aftermarket blocks are drilled for 1/2" head bolts regardless of size or displacement. Now the old GT40 heads he wants to use may still be drilled for 7/16, so just have them opened up to 1/2". Just don't try it yourself unless you a have good quality drill press or even better a bridgeport machine to ensure you don't drift off center or drill at an angle, which you can do very easily by hand.
