bought gt40p heads, slap on or upgrade first?

jons88gt · Dec 17, 2006

I have no idea how many miles are on them but they havent been on a mustang before. I have the gt40p intake as well waiting to get put on. plan on running stock cam for now then upgrading to whatever is recommended for this combo. my question is are my gt40p heads good to go? or do i need to change anything? searching brought up things about switching the springs and some other things. just lookin for a clear answer. thanks

Jon

bubba-dough · Dec 17, 2006

If you don't have headers you will need "P" specific headers or some long tubes work.

jons88gt · Dec 17, 2006

I read about the header thing. ill be ordering some before spring. I just want to know if i should take the heads to an engine builder to upgrade or what. I dont want to have any engine problems.

Jon

jons88gt · Dec 17, 2006

btw the headers i have now are ford motorsport 1 5/8 shorty headers. i assume these wont work

Jon

mob · Dec 17, 2006

The question you should be asking is, should I take my heads to be looked at? And the answer is YES. We cant tell if your heads need anything, but an engine builder will. Just take the heads into a machine shop, tell them you want to have them looked over, check the pressure of the springs, check the valve seals, and all that stuff, shouldnt cost you more then 100 bucks. Now if you have to start replacing things it'll get a little more expensive, but just tell the guy you dont want to replace anything unless its bad.

I bought gt40p heads from a guy, slapped them on, and now im kicking myself for not getting them looked at, because it seems like I have a bad valve seal. Itll cost ya double if something NEEDED to be changed while the heads were off the car, then you gotta take them off, pay to get them fixed, and then spend all the money again to put the heads on. Its a pain in the ass. Get it done while your not in a hurry and their off the car.

25thmustang · Dec 17, 2006

If you have some money to spend, upgrading them will be beneficial. My dads GT40Ps have a little work done to them, and the car made 292 rwhp on a hot day, and threw up a 7.48 in the 1/8th!

Tonys96Cobra · Dec 17, 2006

25thmustang said:
If you have some money to spend, upgrading them will be beneficial. My dads GT40Ps have a little work done to them, and the car made 292 rwhp on a hot day, and threw up a 7.48 in the 1/8th!

I agree, my little Bro has some with bigger valves and mild port work and it runs incredibly well. If you have no moolah, just sjap em on, your stock cam isnt gonna float valves unless they are really worn out. Do you have any info on the explorer they came off?

bubba-dough · Dec 18, 2006

jons88gt said:
btw the headers i have now are ford motorsport 1 5/8 shorty headers. i assume these wont work

Jon

The FRPP headers are P headers. The last 3 numbers in the part # are P50 or P51.

And definately have the heads checked.

v8only · Dec 18, 2006

the older ford racing headers are not p compliant, but newer ones are.

I also agree to have them checked, but 5.0 motors are pretty indestructable. Of course, if they came from a soccor moms explorer, who knows what kind of condition they may be in. You can try putting solvent in the ports and see if it leaks past the valves. That's far from bullitproof, but it'll help a little to see how the seats/valves are.

I'd say bolt em on as is without upgrading anything else. I'm running a stock ho cam and it pulls strong.

jons88gt · Dec 18, 2006

thanks for the advice. I am definately planning on getting them looked at. say eventually Iwanted to throw a supercharger on, how would the stock cam and stock gt40p heads work with that? my guess is that will be a little while down the road.

Jon

jons88gt · Dec 18, 2006

when you say get a little work done to them, what exactly is that. if i go to the shop and say i need a little work done they'll probably think im retarded.

jon

25thmustang · Dec 18, 2006

It depends on what you want for "work".

A milling, valve job, new valves,springs, keepers, and retainers will wake those heads up big time. Then if you want have them ported. It costs a decent amount of money, but will run very hard (right with if not faster than an out of the box aluminum piece)!

jons88gt · Dec 19, 2006

id like to do some upgrading, but not go crazy cause if i wanted the heads to be like the aluminum I would have just bought those. it's a convertible and it will never be at a track. just looking for over 300hp to the flywheel.

Jon

jons88gt · Dec 25, 2006

the heads are at the shop to be "checked out." if I just slap them on the way they are, is a cam recommended or just get the timing tuned right.

Jon

thumper460 · Dec 26, 2006

Up grade the springs now.. the heads are off!! have the shop put new seals and mill the heads flat.. then when you do mod out the engine the heads will be fine... cool??

Just me.....................................

Thumper

85_SS_302_Coupe · Dec 26, 2006

If nothing else, i'd try to put new springs in them. But, if you can take them to a shop and have them milled down a bit, you'll bump up compression a tad and that'll really help a lot. That, new springs, and maybe just clean up the ports a tad and you'll have a nice set of budget heads.

v8only · Dec 26, 2006

jons88gt said:
id like to do some upgrading, but not go crazy cause if i wanted the heads to be like the aluminum I would have just bought those. it's a convertible and it will never be at a track. just looking for over 300hp to the flywheel.

Jon

you're not going to see OVER 300 at the flywheel with gt40/p heads. You'll likely see close to that, but very very very likely not over.

85_SS_302_Coupe · Dec 26, 2006

v8only said:
you're not going to see OVER 300 at the flywheel with gt40/p heads. You'll likely see close to that, but very very very likely not over.

Yeah, if you hit 300hp with an otherwise stock short block, or even with a cam, then you're doing damn good. My buddy dynoed at 299hp with untouched (totally stock down to the springs) P heads on a 347 stroker. He had the heads on just to get the car drivable. I have seen that much from a stock stroke 302 but usually with higher compression heads and a lot of lift on the cam.

thumper460 · Dec 26, 2006

300+ FWHP is well withing the P heads.. the "you cant with the 40's or ported E7s" is a bad rumor.. that IMO, is spread buy the Alum head guys running slower times than the 40's or Ported heads... NO flame here, just an observation!! cool?
do the springs.. seals.. and surfaced flat.. and your rocking..

Just me......................................

Thumper

85_SS_302_Coupe · Dec 26, 2006

Ummm....i don't know if that was aimed towards my statement Thumper, but i was talkin rear wheel hp, not flywheel...just so we're on the same page

bought gt40p heads, slap on or upgrade first?

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