all 351 W's to my knowledge, from 78 on up have 69 cc chamber heads, and the 1.78 intake/1.48 exhaust valves. there are no appreciable difference in them from year to year. Supposedly the HO 351 breaths better but you couldnt prove it by me. If you want good breathing steel heads, go with a set of Roush heads, if you want Aluminum, then I would opt for Twisted Wedge. By the time you got your stock heads worked out etc to flow anywhere near these heads( and you wont), you will have about the price of a set of aftermarket steel heads in them.
Dont get me wrong, I am a hard core Blue Oval type, but I do know the limitations of my heads. The stock heads can be milled up to .050" safely, and that would put you in the neighborhood of around 10-10.5: compression, depending on the pistons, whether dished or flattops. The 69-73 heads had a 60 cc chamber with 1.85 intake / 1.56 exhaust valves. These are probably the best you can find in a stock casting. These engines ran the gamout of from 10.5:1 down to 8 or 8.2:1 compression, depending on pistons. In 74, they went to the smaller intake and exhaust valves.
The only years they had 10.5:1 compression was in 69 and 70, with the 290 hp engine used in the Mustangs.
I don't have a 351 but from all my studys and reading I would have to say the GT-40P heads are the best bang for the buck. They are plentiful and cheap. Even a set of new ones complete is still under $600 I think. You will have to drill the bolt holes out a little to use them on a 351.
i have worked on , and been a fan of fords my whole life. i just recently switched to chevys. it has been my personal experiance, from books and magazines and talking to other people that ford 351w heads are all the same from 69 to 74. these had around 69cc combustion chambers with 1.85 intake and 1.55 exhaust valves. from 1975 and up the valves were smaller at 1.78 and 1.48 the compression differance was in the pistons they used, ethier dome flattop or dished. i have heard the 69 to 74 have a bigger intake port. but if you want a ford head that flows good you'll haft to get an aftermarket set, unless you want to do some exstensive porting. ford heads generally suck.
There are so many brands of aftermarket heads for fords now, building a stock set will end up costing more. For the time and money you will spend to port, larger valves, guides, screw in studs on a stock set, you could of bought a good set of heads.
A little bit of insite here. If you dont want to invest in either getting special pistons or having yours flycut, do not go larger than 1.94 intake / 1.60 exhaust valves. The only exception to that is with the Twisted Wedge which comes with 2.02 intake/ 1.60 exhaust valves and these can be run with stock configuration pistons as long as you dont exceed .520 lift on intake and .540 on exhaust. The reason you can get away with this is because of the relocation of the valves in the combustion chamber. And these heads flow every bit as good or even better than most of the other aftermarket heads with lifts up to .600 ".
They come from TFS with 59 cc chambers. To me, for the gains, they are the best bang for the buck. For a bolt on head, in my opinion, the Roush head or the Wilbert steel head with the 1.94 intake/ 1.60 exhaust are the best buy for the buck, as they will outflow the best you can come up with in a factory head, even after theyve been worked out, and either one is available for about $800. The only thing you need to do is add rocker arms.
I'll chime in, only because 63galaxieguy is my pal UF :thumbup:
He's got a set of GTP heads that we're gonna swap onto his 351 and we're wondering about the loss of compression ratio due to the increase of chamber volume. The concern is that the potential gains from the GT40 heads would be minimalized by a further drop in compression. The intention is do do a cam and head swap without doing anything else to the short block...
We found a source that said the truck heads were 69cc's but can't verify it as 100% correct. If they are indeed 69 cc's then yes the GT40P heads volume would in fact be smaller and the CR would increase. If they are 62.5cc's as machine shop tom indicated, the GT40P heads are larger so the CR would go down. How much can be safetly removed from the GT40P heads to raise compression?
I'd say you have the same E5TE heads that are on my 87 351w engine...they are 69cc roughly and anything is an improvement combustion chamber wise...as far as compression goes. One way to tell without taking the intake off, do you remember what the thermacotor bump looked like? If it was fairly large then its e5, the e7 thermactor bump is noticably smaller than the e5.
I don't believe the couple cc difference is gonna hurt your gains...my guess is your compression will increase as I believe the head you have are 69cc....even if they were 62 the 2 cc loss going with the gt-40p heads isn't gonna be that dramatic, probably not even noticeable, besides the p heads flow so much better.
I suppose you know about using the short spark plug for clearance, using non p headers?
At the very least, since you are going to the effort to put better breathing heads on your engine, I would highly recommend at least upsizing the exhaust valves from the stock 1.48 to the early 351 1.56 size valves, or to the Ford 1.6 valves which are a little more expensive as a rule. Dont opt for putting 1.6 Chevy valves in it as they have quite a bit shorter stem and will put some severe cramps in your valve lift abilities.