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Engine Build Pt. 3

By: Nelson 08/12/2019

It was time for the engine to receive a top end. The stock E7TE heads that came with my engine were in rough shape, not sure why. ANd I wasn't even contemplating using the anemic E4 heads from my original motor. So, a trip to a salvage yard and $50 later I had these:


A set of GT40P heads off a mid 90s Explorer. While it doesn't sound like much, they are actually the best flowing small block Ford heads to ever leave the factory aside from the Boss 302 Cleveland heads. Their Achilles heel is that the stock springs can only support a max of about .450 valve lift, which isn't good for anything performance oriented. Also, stock 5.0 Ford heads are pedestal mount rockers that use a wimpy 5/16" bolts and are known to snap with high lift. With help from a friend, I machined the heads to accept studs and guide plates so I could have a solid valve train.


I gave them a coat of paint


I pulled out all the valves and cleaned all the carbon of them.


Once they were clean I lapped them all and installed them with my new spring package. Viton seals were used, and the springs were all shimmed so they had the correct installed height. Spring pack came from Alex's Parts, they're good to .580 lift and +230 duration. They use a special valve keeper for the exhaust valves unique to the GT40P since I didn't want to change valves. ARP studs & AFR guide plates were used.


The heads were installed with Felpro gaskets. The only factor I couldn't measure was how far the pistons were in the hole, but based on all my other measurements and some internet research the engine should be right about 9.5:1 compression.


And more used parts, a set of Ford Motorsport shorty headers I got from a co-worker. GT40P heads are notorious for having spark plug clearance problems, these are one of the known good headers. Who would have guessed, the Ford parts fit right! Headman & Hooker could learn a thing or two from them.




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