yo,
Good swap!
According to someone who had done this;
The GT40 & 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.
http://i35.photobucket.com/albums/d200/kenfelix/GT40/IMG_0045.jpg
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the heads also have the F3ZE AA casting stamped on the bottom side
http://i35.photobucket.com/albums/d200/kenfelix/GT40/IMG_0048.jpg
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Most accessories brackets bolts on with no problems.
These do NOT have ports for any airpump. 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.
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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
http://i35.photobucket.com/albums/d200/kenfelix/GT40/IMG_0044.jpg
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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.
http://i35.photobucket.com/albums/d200/kenfelix/GT40/IMG_0061.jpg
The bottom of the head has a different casting number than a GT40; miesk5 Note, it is F77E
Both heads boast the same size valve for intake but the exhaust is smaller on the P.
GT40 ( 1.54 )
The oil return galley has the letters GT40P in that valley. This is only place you will see the full GT40P stamp btw.
http://i35.photobucket.com/albums/d200/kenfelix/GT40/IMG_0058.jpg
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.
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.
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more stuff: by variuos folks
re GT40 Heads
if you want to use these on a 351 that you have to ream the head bolt holes out to 1/2" since the 302 size is 7/16".
and more on this by SigEpBlue: "...Actually, you'd want to go a little further. I machined mine to 17/32-inch. Nothing worse than a snug-fitting bolt in a casting. Crack, boom...&
For the general DIY'er, the regular GT40 head is probably the easier option. Better? I don't think so, but it depends upon many intangible things."
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
re; "...These do NOT have ports for any airpump"
Some do.. so look for them
Seems all the GT heads either have smog ports, or one of two styles of plugs. The plugs come either with a press fit or ***** in plug. Mine seem to have the press fit.
Both plugs are removeable, or can be inserted to run without the smog provision. his price on the plugs was 3 to 5 bucks.
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GL!
