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  GT-40P heads???

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Author Topic:   GT-40P heads???
66302Stang
Gearhead

Posts: 205
From: Mesa, AZ, USA
Registered: Aug 2000

posted 03-29-2001 05:23 PM     Click Here to See the Profile for 66302Stang   Click Here to Email 66302Stang     Edit/Delete Message   Reply w/Quote
Will these heads give me any extra power? Is there any way to keep my 10:1 compression with them? What exactly is good about these heads? Thats the weak point on my motor, after the carb & exahsut, and these are the cheapest heads around. How much power can they give me over the 65 289 heads, everything else being equal? Adam

------------------
1966 Mustang Coupe
(soon)
....not yet Finished
302 bored .060 over
Sealed Power Rings
C5AE 65 289 Heads
10:1 compression
218/228 .471/.471 114LSA
65 2 barrel intake,carb
Stock msnifolds (for now)
Glasspacks (for now)
Dual exhaust w/ balance
C4 auto
3.20 rear end
2800lbs
Probably 200-275HP
Hopefully low 15's high 14's

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Boss66
Gearhead

Posts: 150
From: Tucson, AZ
Registered: Feb 2000

posted 03-30-2001 03:08 PM     Click Here to See the Profile for Boss66   Click Here to Email Boss66     Edit/Delete Message   Reply w/Quote
I can't give you too many details but I am using the GT40P heads on my 83gt and the engine seems very strong. I believe the intake valves are the same size as the normal GT40 aluminum heads, but was told once the exhaust side is 1.54 vs 1.64. I'm running the heads with a b303 cam, weiland excellerator intake, Mac 1.5/8 long tube headers, road demon 625 carb, and MSD ignition. I drive the car to work everyday. I can get 20mpg if I try and it has way, way more power than a stock 5.0. I'm currently working on some 4.10 gears to give it a little extra. I have only good things to say about the GT40P heads. Great bang for the buck.

Boss66

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horseballz
Gearhead

Posts: 120
From: LasVegas,NV
Registered: Dec 99

posted 04-01-2001 02:46 PM     Click Here to See the Profile for horseballz   Click Here to Email horseballz     Edit/Delete Message   Reply w/Quote
The only real problem with "GT40-P" heads, is that the only headers that will fit them in an early Mustang are specially made "Tri-Y" (NO LONG TUBES) due to the different spark plug angle.
!!!!!!!!!!!!!!!!!!!!!!
horseballz

------------------
68 coupe
289/3speed(soon to be 5.0/5speed)
68 Coupe
289
C4

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Ken
Gearhead

Posts: 3483
From: Prospect, Ct. M&M Member No. 31 MCA Member 49299
Registered: Jun 99

posted 04-01-2001 03:14 PM     Click Here to See the Profile for Ken   Click Here to Email Ken     Edit/Delete Message   Reply w/Quote
When I asked Alex in an email the above question..... , he stated that as far as he knew there was no problem fitting aftermarket headers on the GT40P heads !!! Besides, the Tri-Y's they tried to sell me were the long tubes (sent them back because of poor chrome and damage)

------------------
Conciousness - that annoying time between naps.

Ken
1965 Springtime Yellow Coupe 302GT40-4spd
www.mustangsandmore.com/ubb/Kens.html

[This message has been edited by Ken (edited 04-01-2001).]

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Boss66
Gearhead

Posts: 150
From: Tucson, AZ
Registered: Feb 2000

posted 04-01-2001 10:58 PM     Click Here to See the Profile for Boss66   Click Here to Email Boss66     Edit/Delete Message   Reply w/Quote
I'm using MAC long tubes specifically made for the P heads. They fit great.

Boss66

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Boss66
Gearhead

Posts: 150
From: Tucson, AZ
Registered: Feb 2000

posted 04-01-2001 11:04 PM     Click Here to See the Profile for Boss66   Click Here to Email Boss66     Edit/Delete Message   Reply w/Quote
Oops. I forgot we are talking about a 66 stang aren't we. I can't say if Mac or anyone else makes headers to fit the P heads in the older stangs.

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