GT40 P heads

67 Tiger

Gold forum user
Messages
298
Anybody try to put these heads on their car? The sparkplugs are relocated. They are spoused to be the best iron head Ford makes, and they were free. I know they also take different headers. Any input would be helpful.
 

michael-king

Gold forum user
CAT Member
Messages
4,132
some notes i have on the GT40P heads:

I installed a set of GT40P heads on my wife's mustang All in all they
work great and I am happy with the result but I did run into a couple of
fitment challenges.

Plugs I used were stock plugs for a 96-97 explorer

Some things to look out for:

Clearance to the headers and especially where the plug wires connect.

Clearance at the bottom of the rockers. I used the Comp Cams roller tip
rockers and the heads I used were modified heads with slightly shorter
Chevy performance valves. It turns out that I should have milled the
stud mounting locations down 100 thousands to clear the bottom of the
rockers. I also had to run .250 SHORTER pushrods to obtain valve train
geometry. Of course if you use stock components this is NOT a problem.

If you have the heads machined for the later model or Mustang 5.0
emissions, be sure to block the exhaust emission holes at the rear of
the heads.



First, all iron heads. The GT40P heads might be one of the best just because
of the valve size - didn't these come with 1.94/1.54 valves? The issue with
Tiger fitment on these is that they do not have the "traditional" spark plug
location and angle and so they may interfere with headers. The E7TE heads
(standard on trucks and Mustangs from '87 on) were the best "traditional" OEM
head as far as I know... and a good base platform for porting if you're so
inclined. I have a couple of sets of the E7TE heads and a set of 1.94/1.54
valves sitting on a shelf just in case I get motivated to build a set of
cheater heads for my 5.0.
There are a couple of vendors of iron aftermarket heads, for race engines in
classes where aluminum heads are not allowed. These heads will typically give
better performance than the OEM heads out of the box, and they'll either have
or allow the use of significantly larger valves without having to compromise
the port shape or inside radius. But they cost a lot more than pulling GT40P
heads from the junkyard, if you don't factor the cost/time equation on
rebuilding and/or porting the heads.
 
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