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Discussion Starter #1
Since I've been on FSB , I've seen so many discussion on Ford's GT40 heads I figure I would post a informational thread that should be a sticky.


The GT40 and GT40P heads are one of the highest flowing heads for the SBF 5.0L applications. These are available online, ebay and in some junkyards if your lucky. Aclot of racers that have to meet stock OEM heads requirements, also uses these heads. You can use these on any 289/302/351W engine. All OEM int/exh manifolds will bolt on.


Let's start with the GT40, these heads can be found on Ford Mustang, Explorer and SVT/truck Lighting applications. These heads also boast the larger exhaust valves but don't flow as much as the GT40P that I will speak about later. These heads also flow more than the other E7 E6 heads which can be found thru out most of the ford car/trucks.

These heads can be found on a few Mustangs upto 1995 and on most of the earlier Ford Explorer applications ( approx 96-98ish). They are easily identify by the tell-tale 3 vertical end marks or by looking at the sparkplug at either end and finding the GT stamp.



Also they have a GT stamped on the top of the head and the one machine flat spot at the corner.



Once the cover is off , the oil return galley also has the words GT.



the heads also have the F3ZE AA casting stamped on the bottom side



Most accessories brackets bolts on with no problems. These do NOT have ports for any airpump and reduce emissions. The combustion chamber has the spark plug almost terminating into the chamber, leading to a better burn and reduce emissions. If your looking for a non worry, direct fit head, that low cost and iron. This is the head to buy and use. Ford racing make the same head in Aluminum btw, but at a higher cost. It might be available in some dealer inventory or thru other suppliers.




next the GT40P heads, this is off my girlfriend car. She blew a gasket and we found a crack exh valve, so I loaned my heads out to her. This head is only found on a explorer. The explorer uses the GT40 and up to 98ish they started converting to the Gt40P for even better emissions reduction. A side benefit to this head, it brings the plug out and puts more flame exposed to the incoming air. The only bad thing about this head, it's plug angle is not ideal with stock exhaust manifolds.


Just like the GT40 it has vertical end markings, but 4 lines



It like the Gt40 has the wording GTP and a single P stamped on the outer edge and near the spark plug hole. The flat spot at the corner of valve cover has the P.



The oil return galley has the letters GT40P in that valley. This is only place you will see the full GT40P stamp btw.



The bottom of the head has a different casting number than a GT40




Both heads boast the same size valve for intake but the exhaust is smaller on the P.

GT40 ( 1.54 )




and GT40P ( 1.46 )



Take note of the spark plug hump and the position of where the plug would be between both heads.


Most accessories brackets bolts on with no problems. These do NOT have ports for any airpump and reduce emissions. The combustion chamber has the spark plug exposed into the chamber, leading to a better burn and reduce emissions than the Gt40s.

If your looking for the highest flowing OEM ford heads, this is the head to buy and use. You will have header problems if your choose to use the factory GT40 or regular manifolds. Most people get by with custom headers and with reduce plugs lengths that are found thru accel, with custom plug wires.


More to come
 

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Discussion Starter #3
btw, I'm adding this photo of a E7 head that I had off my F150 truck. Notice the plug being reduce and in the racer world we call this shrouded by the combustion chamber. Sorry for the picture quality.




Very bad for performance and emissions.
 

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Nice write up I literally just finished swapping GT40's on to my 302. They are from a 94 Cobra.






Now to find out what plugs to use with them?
 

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nice write up but no mustangs ever had gt40 heads from the factory....cobras did but not a plain mustang.

all mustang 5.0s from 1987 to 1995 had the e7 heads
 

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Discussion Starter #6
Thanks for the clarification, I just get loose with the word Cobra & mustangs , when they are two different cars.

Also some marine application used the GT40 heads. Not sure if they ever used the GT40P on a marine application.
 

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broncoflorida said:
Also they have a GT stamped on the top of the head and the one machine flat spot at the corner.

That isn't a machined surface. :goodfinge

broncoflorida said:
Ford racing make the same head in Aluminum btw, but at a higher cost. It might be available in some dealer inventory or thru other suppliers.
GT40X. :thumbup


I agree, this should be a sticky. Good work, florida.
 

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I disagree with this "These do NOT have ports for any airpump and reduce emissions". I cannot speak for automotive applications, but GT 40 heads I have taken from Marine Applications were ported. They obviously were not used and had the (best described as ) "helicoil" style female thread plugs in the tap'd holes.

I have had several, in fact just did a pair & installed on my 90. My second pair was not drilled & tap'd on the ends, but in the exhaust ports, the humps & air passages were there. My machine shop offered to drill & tap to accept the air tube, as this pair was "cleaner" then the pair I was going to use, but I traded them in return for my machine work.


No, GT40P heads were never used in Marine. Reason was exhaust manifolds werent about to change for this, and change came after we stopped using Ford anyway.
 

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Discussion Starter #9
Yours might , but the dozens heads that I've pulled from various fords that have GT40s, don't have thermactor ports or humps or anything else. If you think about the engines these come off, they don't even come equip with a air/smog pump.

Not sure as to what kinda Gt40 heads you claim to have, GT40 heads I've seen don't have such beast. if you disagree, then take pictures of your set and post them. The three holes on the back are accessories mounting holes only.
 

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thanks for the info & pics!
 

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Satyr of the Midwest
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Sorry. Using mine. ;)

Check the boneyards for Explorers from about 1994(?) to 1996 for regular GT40 heads, and 1997-2001 for GT40Ps. They'll be used, but rebuilding them isn't expensive.
 

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Great info.


Didn't someone post along time ago, that Ford Racing does offer a F-truck header for GT40P's?
 

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Satyr of the Midwest
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No, they don't, unfortunately. Only for the Mustangs.

Ryan (Fireguy) had bought a set of Ford Racing headers for the 5.8L Bronco/F-series applications and tried to bolt them to his GT40Ps, but one of the passenger side tubes had to be cut and welded to clear a spark plug.
 

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This is the original thread pertaining to this issue from Cobra Jet who did a swap in 2005......I think it answers everything including part numbers.......

http://www.fullsizebronco.com/forum/...ad.php?t=66998

I saved several of these FSB threads and there is a You-Tube video of GT40 vs GT40P ......it's not well lit so it a bit hard to see.....


Good Luck ~ :thumbup
 

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Discussion Starter #16
also want to add one more vehicle that I forgot to mention. The 1996 mountaineer and newer models have GT40 and Ps heads. So look for the Cobra, Explorer and Mountaineers.
 

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Can I use my stock 302 pushrods for this and what head gasket...?

I want to use the GT40 heads with the thermactor cross-over tube holes for Cali Smog just in case....

Thanks ~ :thumbup
 

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Discussion Starter #18
Don't know if this helps you. But I used the stock pushrod purchased from napa on my FSB. If in doubt, ink your rollers and valve end, and trun the motor over and check the rod to rocker and best fulcrum contact.



Also, for a gasket kit, the explorer 1996 gasket kit for the 5.0L was used in my upper head rebuild. I would think any standard FSB 5.0L kit would be okay since the heads are identical in regard to gasket and the standard truck heads. I bought the explorer gasket kit due to I wanted the GT40 upper gaskets for the plenum.



Here's some more pictures of my heads before I place them on my FSB. I also threw in a photo of the exhaust port where you will see that no smog ports exist. It does have the indentation, but no drilling no boss within and nothing on the outer ends for the smog connections.

GT40 F3ZE -AA casting





So if you want to or need smog ports, then you might want to look for something else. The heads also has the std EGR side ports between the middle cylinders.

EGR source ports

 
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