heads

[joey74]

is the only differants between gt40 and gt40 p heads the spark plug holes

 

[19Walt93]

No, the P heads have slightly smaller exhaust valves and are supposed to make better low end power. The P heads may also have smaller chambers for more compression but I'm not sure. They're both good choices but the P heads need unique headers or manifolds. The 97 Explorers used P heads and had some awful tubular headers, the 98's had lousy cast iron manifolds that may have flowed a little more. I have ported stock E7TE heads on my 351 with 66 Galaxie manifolds and I'm pretty sure 289 Hipo manifolds would work even better. BUT. My firewall is flat with no heater box protruding into the engine compartment.

 

[Angie]

here is a site with a decent "fast" over view of the 40 heads and the "P" heads.

I placed a set of "P"'s into my build. i have no problems with them if you are thinking of using a set on a build. however, my frame is boxed, in a 83, and i took the frame and engine where mounted to a shop and got them to build a set of long tube headers for the build. they started off with a set of BBK longs and reworked them into the frame and heads. I never went down the port or polish, just took them to a head shop to get drilled in rocker studs and built in a set of rollers. very happy with the out come.

cheers

https://lmr.com/products/what-are-gt40-heads-mustang

 

[Elutheros]

I started wiith GT40P heads and the tube exhaust manifolds and eventually put cast manifolds on it. I never could justify the cost of the Torque Monster headers and since it's 4x4 noting else really fits. I had a valve job done on the heads, and later put Alex valve springs on them due to some valve float at high RPM. They work.

 

[rubydist]

Any of the Explorer heads (GT40 or GT40P) need better valves, as the factory ones have low seat pressure and are not stiff enough for high rpm use.

The "P" heads not only have a different spark plug location and smaller exhaust valve as mentioned, but the chamber cc is smaller - 58-60 v. 63-66, so you get a little higher compression. Either of them can be ported to flow pretty well, but imho you are better off to get some AFR Renegade or TF Twisted Wedge heads that flow better to begin with and do not have the header/spark plug issues. For example, the Renegade heads flow as well (right out of the box) as the GT40 heads after they are completely ported. And fully tricked out E7 heads do not flow as well as either of the aftermarket ones I listed. If you want to understand how this stuff works, search youtube for David Vizard.