Gt40 headed combos

[scott5]

There seems to be a few people on here with the GT40 heads.. What kind of combo cam/intake you guys running with these heads?

[frankstang]

GT40 heads // 1.72 rockers // stock cam // GT40 tubular intake // Vortech A trim //
This is on a 306 with full exhaust and 4:10's.

No track or dyno numbers.
I did run it n/a for a while and felt quite a difference over the E7 stuff.

[scott5]

Its going to be a 306 also, with probably a 100 shot.. Gt40 heads, Cobra intake, and got to make up my mind on a cam

[scott5]

anybody else using the comp 281hr??

http://www.compcams.com/Cam_Specs/Ca...csid=1050&sb=2

[Mark Aubele]

I first had a gt40p/explorer intake on my 86 shortblock with a stock cam and speed density, put down 258 at the wheels and went 12.7 at 107, full weight 86 GT on 235/60r15 BFG DR's back in '01. Few years later the car morphed into a 90 notch, with road course oriented suspension (475lb coilovers up front, 3 link and panhard), went to an AFM N-41 and changed the car over to mass-air, and on Toyo RA-1 R-compounds it went 12.48 at 109, obviously not hooking as well as before (1.76 60 compared to 1.70). The heads did have a very minor amount of porting done and good valves, so not truly out of the box. FWIW, both shortblocks (the first died due to a nitrous "mishap") were 100,000 mile plus motors that were just laying around that we tossed together. Decent head for the money IMHO. Times were ran without the shot.

[intel]

There seems to be a few people on here with the GT40 heads.. What kind of combo cam/intake you guys running with these heads?

Budget build...

2001 Mountaineer 5.0 block
Motorsport F roller camshaft
GT-40 P ported heads
Motorsport roller lifters & pushrods
Trick Flow spring kit
Motorsport 1.6 roller rockers
Cloyes double roller timing set
Weiand Stealth intake manifold
Holley 600 carburetor
BBK long tube exhaust headers
Fidanza aluminum flywheel

Rednif Tnuocsid... Lovin it! :D

[White5.0]

gt40p heads with trickflow spring upgrade, cobra intake, 1.6RR, b303 cam. no track or dyno numbers yet but its fun to drive on the street and i drive mine daily. makes good torque.

most people with gt40 combos make ~260-290 rwhp and ~300ft lbs. I hope to get some power pulls this summer to find out for sure where i'm at

[89stang]

Will mac shorty equal length headers fit the p heads? I searched on corral but could not find the answer

[White5.0]

Will mac shorty equal length headers fit the p heads? I searched on corral but could not find the answer

not sure about the equal length, but i know the unequals will fit as i have them on mine with p heads

[PITT40]

I'm glad this thread is here. I have an 86 GT, all stock, speed density, etc. It has MAC shorties and a BBK cold air kit only. I bought a set of GT40P heads and intake from an Explorer I found in the junkyard recently.

I know the 86 heads are junk, so it seemed like a natural upgrade. My questions are; what difference is there in the combustion chamber sizes? Will the P heads flow better but be a lossin compression making the swap a wash on my stock motor? I see the 1.6 & 1.7 rocker combos both being used. Will it be safe using 1.7s with the stock 86 motor and is it worth buying these over 1.6s?

Another thing is that the throttle body was already taken off of the Explorer that I got the heads from. What factory application is best for me to look for a bigger, suitable throttle body to use? I doubt I would want to use the little stock 86 throttle body with this combo.

I 'm new the EFI stuff, so I need some advise! Thanks in advance.

[Mark Aubele]

I'm glad this thread is here. I have an 86 GT, all stock, speed density, etc. It has MAC shorties and a BBK cold air kit only. I bought a set of GT40P heads and intake from an Explorer I found in the junkyard recently.

I know the 86 heads are junk, so it seemed like a natural upgrade. My questions are; what difference is there in the combustion chamber sizes? Will the P heads flow better but be a lossin compression making the swap a wash on my stock motor? I see the 1.6 & 1.7 rocker combos both being used. Will it be safe using 1.7s with the stock 86 motor and is it worth buying these over 1.6s?

Another thing is that the throttle body was already taken off of the Explorer that I got the heads from. What factory application is best for me to look for a bigger, suitable throttle body to use? I doubt I would want to use the little stock 86 throttle body with this combo.

I 'm new the EFI stuff, so I need some advise! Thanks in advance.

I can't remember the actual combustion chamber sizes, but they will not be a wash swapping from the utterly pathetic 86 GT heads. I picked up 77 rwhp (from 181 to 258, and thats goin from LT's to shorties) and went from 13.8 at 94 to 12.7 at 106 (on DR's) with only a head change. 1.7's WILL NOT work on your short block. You have no valve reliefs. Even with stock valve sizes (with stock 1.6's) I had tell tale signs of valves kissing the pistons after I blew it up sucking a hidden nitrous nozzle in after I pulled the heads. Use a 65 mm TB and make sure you put at least a 155 lph FP in the tank, and you will need an adj. regulator when keeping the SD (which will work great with an exploder intake and heads and stock cam). If I remember corrrectly I was at 46 psi of fuel pressure, and it was incredibly sensitive to changes with the SD, I'm talking 3 mph in the quarter going from 40 psi to 46. Good luck, it is a great combo for no money. The 86 heads are garbage more than you can imagine. Wait until you get them off and look at them. A P head would make more power on an 8 to 1 motor than the 86 heads would make on an 11 to 1. Funny thing is the heads and intake cost less than most bolt ons that don't anywhere near the power. Worth noting those numbers were back in '01 on a tired 140,000 mile shortblock that burned about a gallon of oil every five minutes.

[PITT40]

Thanks for the info.

Where do a I get a 65mm TB? Is it available in a bone yard off an Explorer, truck, Linc MkVII or VIII, Mod motor Mustang or Crown Vic? Or is it an aftermarket buy?

[Mark Aubele]

I'm not too sure about factory ones that work, a bunch are 65mm. Always got mine in trade for something stupid when someone I knew wanted to put a 10 inch TB on their car for some reason. You're car has a 58mm on it, not 60 like the 87-95's. Anything would be better.