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We're working with a 95 Mustang GT 5.0 5speed. Went to put plugs in it the other day and found out the plugs I got for my GT wouldn't screw into the head. The old plugs that came out were plugs for a 5.0 Cobra motor (Autolite APP104's). After doing some research, looks like its got GT40P's and possibly an Explorer intake.

I'd like to know if there are any casting numbers or ways to positively identify the GT40P's and Explorer intake. Also, kind of curious if it might just be a whole entire Explorer long block swap. Any ways to find out? Thanks in advance!
 

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To identify the parts, use a visual check. The later 5.0L heads have vertical bars cast into both ends. 2 bars = E7 /standard and HO heads. 3 bars = GT40 cobra and non-P Explorer. 4 bars = GT40P Explorer with the angled spark plugs. They alsp have GT and 40 cast at the top corners of the valve cover area on the outside so you can see them with the covers on. The GT40Ps also have a P cast into the corner. The GT heads flow almost identically, with the P heads having the edge from .300 to .500 lift, and the non-P heads a bit better under .300 and over .500. If porting, take your pick, but the exhaust valves on the GT40 are larger, and headers that fit the plugs are more common.

The intakes are really similar, with the lower intake for all practical purposes identical. Cobra and early GT40 lowers have a charge temp sensor in runner #5, and the later '97+ GT40s do not, but do have the cast boss there. The uppers are obviously different, with three types - Cobra tubular, Cobra cast, and Explorer cast. The tubular one is a giveaway, the Cobra cast is smooth around the plenum where the air distributes to the runners, and the Explorer has ribs cast on the top and sides of that area.

The short-block? If the front accessories and oil pan have been swapped to the car type, there is only one way to know for sure without a Bor-o-scope and without opening it up - the cam. While Cobras had 1.7 ratio cast aluminum rockers, the Explorer had 1.6 ratio stamped steel, and it could have either. Take off a valve cover and set a dial indicator on the intake and then exhaust of one cylinder. The actual measurement doesn't matter. If it has a Cobra cam, the lift will be the same. If it's an Explorer cam, the intake lift at the valve will be about .030 less than the exhaust. There ya go. BTW, on the dyno, the Explorer engine actually out-powered the Cobra engine by a hair, as it used the better dyno headers, the weak-link for stock HP ratings.

David

Cobra cast:


Explorer GT40:



5.0L lowers for comparison:
 

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Discussion Starter #3
Thanks for the response Dave! Great, very useful info!
 
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