Not sure which set of these I should use.

68stang351 · Jun 1, 2011

After I put TW heads on my 351w in my 68, I had planned on putting the 69 351w heads on my 90. But I just recently bought a set of GT40P's for like 60$ and a trade of a nitrous plate.

I'm not really sure which heads I want to go on the 90. If I use the GT40P heads, I believe I can re-use my beehive springs and roller rockers from my E7's. Is this correct? But then I have to find a set of headers too.

If I use the 69 351w heads, I'll either have to use the stock stamped rockers or buy new ones.

They both have the a 1.84 intake valve (vs E7's 1.78), but the the P heads have the same size exhaust valve as the E7 (1.46) while the 351w head has a 1.54 exhaust. It looks like I would gain compression with the 351w head also.

I wonder which one has the better chamber design?

Mustang5L5 · Jun 1, 2011

The p heads angled spark plug puts the electrode tip in a better location. Those are the heads I would prefer to use.

You can reuse your e7 springs if using the stock cam...anything more aggressive and you'll want performance springs. Keep in mind, e7 springs aren't great either...but better than the explorer stuff.

You can use regular headers with some 90* boots and plug boot protectors

1bad67sbf · Jun 1, 2011

i would say go with the 351 heads, they will flow better and are a good set of heads. sell the 40's and use that money toward getting new roller rockers and springs. im sure you know but in the classic car world 351W heads are highly recommended for good performance from cast heads.

1bad67sbf · Jun 1, 2011

did you unass your smog stuff? if not the 351's most likley wont work due to no air ports in the rear of the heads.

68stang351 · Jun 1, 2011

Mustang5L5 said:
The p heads angled spark plug puts the electrode tip in a better location. Those are the heads I would prefer to use.

You can reuse your e7 springs if using the stock cam...anything more aggressive and you'll want performance springs. Keep in mind, e7 springs aren't great either...but better than the explorer stuff.

You can use regular headers with some 90* boots and plug boot protectors

As stated, my E7's already have aftermarket beehive springs, it has an E cam. Didn't know I could use regular headers!

1bad67sbf said:
i would say go with the 351 heads, they will flow better and are a good set of heads. sell the 40's and use that money toward getting new roller rockers and springs. im sure you know but in the classic car world 351W heads are highly recommended for good performance from cast heads.

1bad67sbf said:
did you unass your smog stuff? if not the 351's most likley wont work due to no air ports in the rear of the heads.

Smog stuff is long gone.
That was my original plan, to use the 351w heads, until this deal came along.

NIKwoaC · Jun 1, 2011

I'd be tempted to use the GT40Ps. Unless the Windsor heads flow a bunch more wind than the 40Ps, the 40Ps are going to have a more updated combustion chamber and more modern ports, thus would likely be the better head. But I have no idea what the flow numbers look like between the two heads, so I can't say for sure.

Mr. Rustypwnz · Jun 2, 2011

1bad67sbf said:
i would say go with the 351 heads, they will flow better and are a good set of heads. sell the 40's and use that money toward getting new roller rockers and springs. im sure you know but in the classic car world 351W heads are highly recommended for good performance from cast heads.

p heads blow the 351 heads away stock for stock!

1bad67sbf · Jun 2, 2011

whats the date code on the 351's?

85_SS_302_Coupe · Jun 2, 2011

The Ps may have smaller exhaust valves but they actually flowed more on the exhaust side than the non P version did, even with the smaller valves. It has to do with port shape and port velocity.

That said, if i had to choose one or the other i would probably just use the Ps because you won't have to deal with changing them over to screw in studs and then deal with guide plates and buy different rockers. The Ps are a straight bolt on except for crappy valve springs and the header issue.

I have C90E's on my 347, but they've been ported so much they're not really a good comparison.

68stang351 · Jun 2, 2011

I'll probably just use the P's then, and swap over my aftermarket springs and roller rockers from my E7's.

Thanks.

Not sure which set of these I should use.

68stang351

Mustang5L5

That is…until I whipped out my Bissell

1bad67sbf

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1bad67sbf

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68stang351

NIKwoaC

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Mr. Rustypwnz

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1bad67sbf

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85_SS_302_Coupe

it sucks (I know) to be on the receiving end

68stang351

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Not sure which set of these I should use.

That is…until I whipped out my Bissell

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