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Would these heads work on my '95

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Grand Poobah
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    Posted: August-14-2010 at 11:07pm
Would these heads work on my '95 GT-40 multiport EFI??

Next is a set of GT40P's. While this style was used on an explorer, these are ford motorsports heads, not take offs and there is a difference.

the explorer heads use lighter springs and a mass production valve job - meaning they cut the face angle and let the valve pound in the seat angle. the FMS heads have a straigher surface (Under .001"), a true 3 angle job, and heavier valve springs tolerant to .500 lift at 6500+ without float. They were never installed on anything - just painted 'new ford blue' and sat. For my 347 this gives me a 9.5:1 CR on my dished pistons, but I have exhaust issues since the FMS P50 headers are designed for the mustang as bolt ins and not the truck.

If you have an EFI mustang GT or similar motor, these heads are worth 40hp bolting on as is over your stock E7TE heads. Numerous tests show they outflow the GT40 iron head at all lifts under .500 and are perfect with the E303 or equivalent cam.
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Gary S View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gary S Quote  Post ReplyReply Direct Link To This Post Posted: August-14-2010 at 11:48pm
How much is he asking for them? What size valves in them?Tristate sells them with a warranty for 600
69 Mustang HM SS
95 Nautique Super Sport
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gun-driver Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2010 at 12:12am
He was asking $500/OBO

He didn't state valve size in the ad. I'm waiting on a call back.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote horkn Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2010 at 1:13pm
Those will work just fine.

There was no FMS GT40p head. The GT40P head was created by ford (not FMS or FRPP) for their existing 5.0 powered vehicles, namely the 5.0 explorer to make emissions tests come out better.   This was never a racing derived part, but it happened to work very well for many applications sine it was a very good head design. Actually, it ended up making better power than most if not all other ford iron heads, FRPP or FMS.


While they made better power, they were PITA to get to fit on most 5.0 powered cars, outside of the explorer due to the new spark plug angle. Some companies made or make special headers for certain vehicles to use the gt40p's. It just so happened that the marine exhaust on a PCM actually made spark plug access even better on these boats with the gt40Ps than the normal spark plug location that most ford heads do.

Following Information Taken From Car Craft Magazine on GT40P Heads..
GT40P Head Data:
Valve Size: 1.84 intake 1.46 exhaust
Chamber Volume: 59 cc
Intake Runner volume: 145 cc
Valve Spring (seat) 90 lbs @ 2.00
Valve Spring (@ .500 lift) 310 lbs @ 1.500
Valve Spring (coil-bind) 1.300
Retainer To Seat Contact 0.75 intake/ 0.77 exhaust
Ex/Intake Flow Ratio 66.8 @ 5.00 lift
Max Power (theoretical) 398 HP @ 5.00 lift
59 cc head raises compression about 0.6 point - when replacing a 65cc
head on a 5.0 engine
78 martinique- refloored, reinforced, stringers re glassed, re engineered interior
GT40P heads Edelbrock Performer intake acme 4 blade
http://img.photobucket.com/albums/v64/horkn/fish/nautique.jpg
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TRBenj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TRBenj Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2010 at 4:57pm
Yes, they will fit. Why are you considering swapping- something wrong with the stock heads on your GT40? That would have had GT40 heads originally, and while the P heads are a *little* better, theyre not worth the cost and hassle to upgrade.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote GottaSki Quote  Post ReplyReply Direct Link To This Post Posted: August-15-2010 at 5:00pm
Originally posted by TRBenj TRBenj wrote:

theyre not worth the cost and hassle to upgrade.


I was thinking the same thing
"There is nothing, absolutely nothing, half so much worthwhile as messing around with boats...simply messing."

River Rat to Mole
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gun-driver Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2010 at 1:12am

When I bought the boat it had a hairline crack in the port side head. Some JB Weld has kept it at bay but I would like to replace them this winter.
I'm still nervous that someday it will just let go, so the swap is mostly for piece of mind.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote TRBenj Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2010 at 10:59am
Gotcha. In that case, going to P heads isnt the worst idea in the world. Unless that guy is selling the heads in question very cheaply, I wouldnt entertain them. Stick with tried and true head outfits like Tristate or Clearwater. Tristate is the way to go if you want to upgrade the cam, as their heads ship with upgraded valvesprings. If youre looking to keep the rest of the motor stock, then go with Clearwater, as their prices are very reasonable.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gun-driver Quote  Post ReplyReply Direct Link To This Post Posted: August-16-2010 at 1:58pm
I was thinking about a cam upgrade while I'm in there, but I don't know if that would effect the EFI. I don't want to get into messing around with that.
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