explorer heads?
Thread Starter
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Senior User
Joined: Oct 2006
Posts: 148
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From: las vegas
explorer heads?
I have seen this statement in many posts. I have really started to wonder what these really are. Are they heads that came out of a ford explorer? If so what year should I be looking for? If not, allow me the opportunity to let you gloat and boast.
I would really like to know more. Are they possible to find in a junk yard? All the good stuff.
I would really like to know more. Are they possible to find in a junk yard? All the good stuff.
Laughing Gas
Joined: Dec 2003
Posts: 900
Likes: 3
Go to a search engine like google etc and run a search on GT40P. You'll find lots of articles and forum links. They have a different sparkplug angle which interferes with some exhaust manifolds/headers. They also raise the compression ratio slightly.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
The Explorer 5.0 was available from 1996 to 2001. Nothing before that. The GT40P heads appeared in mid 96. The early 96 heads are the same castings used on the Cobra Stangs, Lightnings and Marine engines.
Hotshot
Joined: May 2004
Posts: 12,170
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From: The hills of No. Calif.
The P heads have a revised combustion chamber configuration with relocated spark plugs that allows them to burn cleaner without the use of air injection while making good power. They aren't even drilled for Thermactor passages. They also have smaller exhaust valves and are designed to have a higher exhaust port velocity. I have a set which I've done some very mild port cleanup to as well as converted to screw-in studs with guide plates, but haven't yet run them.
They require special P-specific headers (Mac makes a P-specific shorty header for them which I'm told fits well) as the exhast ports are oval rather than square and the relocated spark plugs makes for a tight fit with standard headers. I used an old set of oval tube headers I had for mine, but I had to extensvely rework the driver's side header. I should have just forked over the bucks for the P-specific headers...
They require special P-specific headers (Mac makes a P-specific shorty header for them which I'm told fits well) as the exhast ports are oval rather than square and the relocated spark plugs makes for a tight fit with standard headers. I used an old set of oval tube headers I had for mine, but I had to extensvely rework the driver's side header. I should have just forked over the bucks for the P-specific headers...
Postmaster
Joined: Dec 2004
Posts: 2,941
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From: Maple Valley, WA
The P heads Started showing up on explorers and Mountaineers in early/mid 97 not in 96. The 96's and early 97's had regular GT40's of 93-95 cobra/lightning fame. The GT40's didnt have Thermactor ports either, it has nothing to do with the P's more effiecient chamber. You dont have to have P specific headers in most applications if you use 90 degree spark plug boots, all depends on the header being used though. The P heads flow around 5 CFM more on the intake side than the original GT40's and flow better on the exhaust side with a smaller valve. The regular GT40's have a bigger 1.54" exhaust valve so they are more capable of flowing better with a little porting (bowl work, raising the port, etc). Both heads are a good upgrade over E7's and with a little port work and some milling (gt40's) they can be a fairly formidable head for the 5.0.
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Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
97 instead of 96----Ooopppsssssss!!!!!!!! 
The "P"'s centrally located spark plug had to do with the improved emissions. The chamber itself is damn close to the E7 in shape.
The "P"'s centrally located spark plug had to do with the improved emissions. The chamber itself is damn close to the E7 in shape.
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Postmaster
Joined: Dec 2004
Posts: 2,941
Likes: 30
From: Maple Valley, WA
I was just comparing My regular gt40's to some E7's tonight and its amazing how much more the Spark plug protrudes into the chamber. The P's protrude even more at a better angle which provides a better flame front. The huge spark plug boss in the chamber is part of the reason that P's have a better compression ratio as well. But a huge difference in emissions reduction between the P's and regular GT40's, I dont think there was much.
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Senior User
Joined: Oct 2006
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From: las vegas
I knew if I allowed people the opportunity to display their wisdom, they would. Tons of great stuff there folks. I happened to notice everyone mentioning 5.0. I have the 351W. After tons of reading on this mecca of ford know how, I have found out that the 5.0 and 5.8 have different bolt sizes for the heads. Is the explorer head still a good idea for the 5.8? I am planning to pull the current engine out and rebuild. I would like to continue using the 351W I have in there. Is that adviseable or not. If it matters, it will be going (currently is still in) in my 72 100. Still confused on if I should stay or change to something different for a powerplant. 
Postmaster
Joined: Dec 2004
Posts: 2,941
Likes: 30
From: Maple Valley, WA
The GT40/GT40P's will be better than any other production Ford head and well worth the $200 you can get them for. I just got a set of GT40's with half the explorer intake and a TB for $125 on craigslist. Just drill out the head bolt holes to accept the 1/2" head bolts and your set. The 93-95 lightnings cam stock with the GT40 package on a 351w.
Fleet Mechanic
Joined: Jan 2005
Posts: 1,413
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From: cape may county NJ
Hi guys I am not in here much but this topic has struck an intrest,I have a friend that has a 96 or 97 mountaineer with a 5.0 that fried the lower end and he is putting a 5.0 ho motor in and it was already set up for a truck.What I want to know is what should I get from the moutaineer motor before it gets junked block has a hole from a rod we think(its not out yet and we cant see where).I have a 86 5.0 in my truck and have been toying with the idea of rebuilding it and any performance upgrades I can get free is a good thing.
Posting Guru
Joined: Mar 2006
Posts: 1,526
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From: fargo, nd
id take the whole top end- the computer, the wiring, the intake, the heads, the spider and retaining clips and lifters for the hydraulic roller cam, the exhaust manifolds, the water pump (never hurts to have a spare) basically whatever you have room to store- take off. the shortblock is about all you should take to the scrapyard.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Originally Posted by xfordman
What spark plug should we run in the GT40p heads. My parts house only showed a platinum type plug. Thanks