Heads
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Good---they out flow stock E7's. Bad? the different spark plug angle interferes with many headers designed for other small block heads. There's no difference in intake manifold fit---same intakes that fit other small block Ford heads fit the GT40P's too.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
All you need to do to the E7's is open the exhaust sides, removing the Thermactor bumps in the process and blend the bowls under the valves. Anything more, and you really need either professionally ported heads or buy better aftermarket ones to start with. And bigger flow isn't always better, there is such a thing as "too much", this depends on the application and intended use..
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Postmaster
Joined: Dec 2006
Posts: 2,866
Likes: 1
From: Rockford, Il
mind if i chime in... thinking about stroking my 351 for a torque increase to help tow. what heads would help, i do want iron, and dont want to drop a wad of cash, remember i just want alot of grunt. thanks. Dan
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Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
For what you want--- stick with iron heads and no bigger than 1.94 intake valves. Something like a "middle of the road" head, better than stock, but not the super high flowing heads. World Products Windsor Sr's is one that comes to mind.Although they only come with 2.02 valves. Or a ported set of Iron GT40's.
Senior User
Joined: Aug 2007
Posts: 388
Likes: 0
From: CANADA
GT40Ps are a very good head. All the head flow data ive seen has shown that the Ps match the windsor jrs and even beating them most of the time at low lift (Ps pretty mutch peter out at .500 lift though) I have also seen some numbers on the Ps vs reg GT40s and the Ps outflow them, especially on the exhaust side (the Ps have a smaller exhaust valve, if that doesnt say something about port velocity I dont know what does). GT40Ps only real down fall is the angled plugs but there are starting to be more headers made for them. Even if you decide on something else and find some Ps for a decent price Id pick them up anyway.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
The P's flow better with the smaller exhaust valve cause they don't have the Thermactor bumps to impede the flow.(they don't have the Thermactor passages either) You can effectively do the same thing in opening up the E7 head exhaust ports, you'll just have the smaller intake valves though.
Senior User
Joined: Aug 2007
Posts: 388
Likes: 0
From: CANADA
Originally Posted by baddad457
The P's flow better with the smaller exhaust valve cause they don't have the Thermactor bumps to impede the flow.(they don't have the Thermactor passages either) You can effectively do the same thing in opening up the E7 head exhaust ports, you'll just have the smaller intake valves though.