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Thread: Gt40p heads

  1. #1

    Default Gt40p heads

    Looking to put gt40p heads on my stock 82 302. Are these direct fit heads? Or are there any clearance issues?. Or is a gt 40 head better for non clearance problems? Thanks

  2. #2

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    Only issue I know of is the funky plug placement makes header selection critical. From everything I have read they are the best of the stock heads (non-aluminum).

  3. #3
    FEP Super Member bwguardian's Avatar
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    The only thing you will run into is as mentioned above, the location of the spark plugs relative to the exhaust manifold/header. Depending on what you have, the 90* spark plug wires will probably be all you need. This is for the GT40p heads and I don't think there are issues with the GT40 heads. I dealt with this with my GT40p heads until I was able to get a set of Ford Racing stainless headers.

    The 2 heads are about the same when looking at the numbers with the GT40p heads having a slight edge. Where they differ is the combustion chamber size. Going from your heads to the GT40p heads will bump your compression by about a point...so hello bottom end torque.
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  4. #4

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    And the p heads have crap springs.
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

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    FEP Senior Member 854vragtop's Avatar
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    Check out these links regarding porting the GT-40P heads. Great info on the do's and don'ts on where and where not to cut.

    http://www.diyporting.com/
    http://www.diyporting.com/PIupdate.html
    http://www.diyporting.com/gtpin.html
    http://www.diyporting.com/gtpex.html

    I used Alex's Springs to replace the stock Explorer valve springs.
    https://www.alexsparts.com/sb-ford-g...ft-vsk7h49-13/
    https://www.alexsparts.com/categorie...GT40P%2C-GT40/

    I also ended up replacing my stock pushrods after installing the GT-40P's and using an adjustable pushrod measuring tool.

    7622-16 COMP Cams Magnum Pushrods
    CCA-7701-1 COMP Cams Hi-Tech Pushrod Length Checking Tools


    These are the headers that I installed, but it looks like they're getting hard to find now.
    FMS-M-9430-P50 (VP) HEADERS

    Definitely a must (or research another brand that works)

    I dug up an old e-mail where I had e-mailed a bunch of research on springs (quotes from various online forums) to myself so I wouldn't lose the info. It's all listed between the *** below.

    ***

    What springs to use for GT40P's?

    http://www.fiveohinfo.com/performance/gt40-gt40p.html

    The stock springs that come installed on GT40P heads (remember, GT40P's come from factory Explorers/Mountaineers, they cannot be bought new) are awful. They may not even hold up to a 5.0L V8 Mustang's stock HO cam, rated at 0.444 lift with the stock 1.6 rockers. When installing GT40P's, it's imperitive you replace the springs. Of course, what spring package you pick is totally dependent on what cam and rocker combination you will be using. If you're sticking with the stock HO cam, take a look at the Trickflow spring upgrade kit (#TFS-2500100). It can handle up to .520 lift and is a bargain at $150. The Crane Beehive Spring Kit (#44308-1) is another great option, good to 0.550 lift and reasonably priced at $162. Both are available from Summit (summitracing.com). Alex's Parts (alexparts.com) is another great place to look for a drop-in spring package.

    Keep in mind though that the cost of a spring package adds onto your overall costs of the heads. i.e: You buy a set of stock GT40P's for $150, don't forget the added $150 for springs. Thus your total cost is $300. Now this is not bad at all, just a reminder of potential hidden costs.

    GT40p Head, E Cam, What Valve Springs?

    Hi, jj. I have pretty close to the same thing that you have, except I'm using a Trick Flow cam. The valve springs recommended for that is the TF Ford upgrade kit (TFS-2500100) which has the springs, keepers, two sets of retainers (one intake, one exhaust, they're different) shims and an installed height measuring device. This kit was installed on my GT40P heads without any machining and is rated for a lift of .520" max. Your E303 cam has a lift (assuming 1.6 rockers) of .498" which is well wthin the specs. There will be as many opinions on this as the number of people you ask but there's my take on it.
    Rick

    I'm doing a very similar GT40P setup and am thinking of going with this: http://www.alexsparts.com/products/S...YD-ROLLER.html
    No machining, 2 sets (intake & exhaust) of retainers & keepers included, up to .600" lift. They are highly recommended by some real gear heads on another forum. Anyone here familiar with them? My alternate choice is the TFS kit.

    http://www.alexsparts.com/sb-ford-gt...it-hyd-roller/
    ***
    Last edited by 854vragtop; 01-01-2018 at 10:16 AM.
    '85 Mustang convertible GT, 5 speed, 4V
    Stock bottom end, Comp Cams XE264HR-14, GT-40P heads w/ Alex's springs, Weiand 8124 Street Warrior,
    Summit Racing 600CFM carb, 8.8 Turbo Coupe rear end w/ 3.55 gears, '94/'95 Cobra brakes, '85 Town Car M/C, '93 Cobra booster, MM Panhard Bar, MM Strut Tower Brace, MM 4 point K-member Brace

    '68 Mercury Cougar, w/ '88 5.0L, 4V
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    FEP Power Member Ourobos's Avatar
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    If both are available to you, get the GT40s.
    1986 CHP SSP Coupe

  7. #7

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    What about a multi-angle valve versus porting? I'm going to drop a 2000 Explorer 5.0 into a '66 Mustang. I'll change the cam and springs but I don't really want to port the heads.

  8. #8

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    Do you need to port the heads?
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  9. #9

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    That's what I'm asking 'Stack. I'll be happy with 270+HP. If I can get that with just a cam and spring swap and adding a 4V carb with a good dual plane intake, I'll be fine.

  10. #10
    FEP Power Member Ourobos's Avatar
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    Had a friend just put his on a chassis dyno.. Stock 302, GT40 heads, GT40 intake, few minor bolt on (I THINK stock cam). Made 230 to the tires.. That's about 255 HP...
    1986 CHP SSP Coupe

  11. #11
    FEP Super Member bwguardian's Avatar
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    Quote Originally Posted by rose62 View Post
    What about a multi-angle valve versus porting? I'm going to drop a 2000 Explorer 5.0 into a '66 Mustang. I'll change the cam and springs but I don't really want to port the heads.
    Those would be GT40P heads and you need to be careful with any porting as they can easily be messed up rather than helping. You should be fine with a cam around .500 lift and an LSA of 110* for a carburetor with a good dual plane intake.
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  12. #12

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    I've seen h.o. stock cams on explorer blocks put down close to 300rwhp on fuel injected setups. With a good intake and carb, you should be able to make 275hp. Maybe a bit more with a better cam
    2 1986 cougars (both 4 eyed and 5.0)
    1 1987 cougar

  13. #13
    Moderator wraithracing's Avatar
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    Quote Originally Posted by Ourobos View Post
    Had a friend just put his on a chassis dyno.. Stock 302, GT40 heads, GT40 intake, few minor bolt on (I THINK stock cam). Made 230 to the tires.. That's about 255 HP...
    15% HP loss to the wheels is pretty standard rule. Using that estimate means the engine above is most likely closer to 270 HP at the crank.
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    FEP Super Member erratic50's Avatar
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    Keep in mind that the GT40 and GT40P heads were a great stunt when nothing else was really available for a cost effective price but they are a real turd now compared to a decent set of heads.

    Personally I'd track down some small chamber AL Edelbrock heads then blow the spring and cam budget on reconditioning. At 11:1 with an HO roller cam and 1.7:1 rockers a 302 on race gas or E85 will dyno out to over 400HP so you will net about 350.

    Assuming headers and a great intake and aggressive timing, etc.

    A twisted wedge head would allow for larger valves without piston notches but you will have to use a lumpy cam and rev it to the moon (7000+) to see any benefit on a 302. And mind you it will only benefit at peak. Area under the curve is with smaller CC intake runners on the heads and inherently those heads have the smaller valves like the GT40P has.

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    FEP Super Member xctasy's Avatar
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    Yep, word up, erratic50!

    Ford had a boat load of parts on the list, but pulled them on the 11 th hour with Operation Desrt Storm.

    After things got back on track, 911 ment the 2001 gun gear becaome CNC ported US GT40P heads. These made an easy 295 hp net and 321 lb-ft on a little GT40 intake and GT40P headed 5.0.

    Bascailly ther Explorer engine, with better cam and 1993-Cobra and SVT 95 351R bits blended into the 1997-2001 Explorer/Mountaineer SUV engine.

    By 2002, it made 335 hp net and 369 lb-ft with a 400 thou over, 3.4" stroker crank and some other intake and very mild cam and roller lifter mods.

    The Cobra/SVT GT40 intake was very, very restrictive, not the heads. The 425 hp FRPP claim for the Showa made GT40 upper and lower intake is just horsepoo unless your cam miester is a genuiys and there has been some additional interanl work.


    The modern day custom cam does the duty on making a restrictive head and intake combination make power, but the last GT40P heads themselves are pretty stout.


    The GT40's have nice big exhaust valves, and easy going potential, the GT40P's are potentially much beter than GT40's, but each are not stout compared to any other modern aluminum 5.0/5.8 able to fit Windsorhead.

    Alan Rootes Trick Flow Specialities head was the water shed development Ford needed. The later Ford branded 302x and whatever else Ford or aftermarket alloy head replacements came out in rapid fire order. Anything alloy with flow numbers, intake runner volume and some co-oberating history is normally a dead cert for a HUGE improvement over any iron 1993-2001 Emmisions era heads.

    Just remember, though, a stock 4V intake reworked internally, a custom roller cam and a set of worked 1984 5.0 heads can make an easy 390 hp net if you spend the time. Ford USA pulled the pin on the British built Ford Advance Vechicles Mark III GT40 cars due to the expense of making them road legal in the USA. Before then , all 31 "road" cars were from GT40P/1043 to about GT40P/1074 were Quad IDA 289 equiped 390 hp gross engines geared for 165 mph. There were 87 other GT40P/1000 to GT40P 1086.

    This was where the slang term for the GT40 and GT40P heads came from, because they had improved production K code Shelby Cobra head castings, designed for Le Mans. The stock Shelby GT350 engines were 306 hp Gross/329 lb-ft Gross , but there were two production press cars ( P/1013 was always 4 x 2-bbl IDA Weber, P/1028 was twin 4-bbl Le Mans bowl 4150 Holley) with the Colloti gearbox. They were orginally supposed to be Webered engines were listed variously as 335 hp Net at 7000, 312 lb-ft net at 5000 rpm, or 380 to 390 hp Gross at 7000 rpm and 326 lb-ft at 5000 rpm.

    With the last 8 July to September 1968 build DS25 ZF gearboxed Mark III GT40'S like M3/1104 and M3/1105 had 6500 rpm red line 585 cfm 4-bbl Holley Cobra K code cammed 306 hp/329 lb-ft 289's, or the more fortified 7000 rpm red lined Lemans cammed K code based 289 and its four times 2-bbl Weber IDA'S...390 HP SAE Gross.

    Stock GT40 Mark I head are really K code heads with modifications. A modern day variation would be what a set of GT40 non angle plugged heads could do.

    The Mark III's were under-rated, about the same as the SAE net readings, but they were just K code Shelby GT350 engines.

    The guys who raced Group A found the Ford E3 headed engines wanting, but the same time, 1984-1987 Holden guys got factory roller rockers but flat tappet cams, and made 430 to 460 hp with stock 5.0 liter GM H heads.


    Ford 5.0 GT Mustang heads from 1983 to 1985 were restricted not in anything but


    1. not having Cleveland style lift, 1.7:1 roller cam rocker ratios,


    2. and no having proper casting thicknesses in the castings and water jackets to address getting the exhaust side opened up enough to balance the development work the intakes and ports could take.

    Clevelands alloy offshoots were the go to Development heads, and if you wanted a grunty 5.0, you found a GTP car, and a A3 head and some kind of Motorsport block, and went SVO or WCP 351.

    I hate the stop bit that years of non development of the wedge head Windsors suffered. The upshot is how great the alloy heads and camshafts are now.

  16. #16
    FEP Super Member erratic50's Avatar
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    What's funny is It's rare to see a Windsor style head that flows anywhere near the old Cleveland heads. A stout AFR or TFS or Edelbrock head will flow 230 CFM per port intake.

    Clevelands could go past 300 but had chronic detonation risks. A clevor is a bear to tune to go the distance but power potential is unreal. Especially radically canned shooting for gains up top and on an aftermarket block-- its unreal what a lowly 302 will put out running 9000 when everything is right.

    Anyway...... given the cost of springs and gaskets and what your time is worth and costs of better parts vs the 40's I would not bother with GT40 or GT40P. heads in most cases.

    There is a notion of good enough that can't be overlooked though too.

    whatever you decide -- good luck with your build.

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