Finalized GT40P headswap, initial thoughts

[TomCat]

Yup, got everything done today and after about an hour of timing, putting fluids back in and making sure there were no leaks, took her for a spin and let me say WOW. I can't believe what a difference it makes to have a nice(er) set of heads on these cars. I'm just stoked, so I had to tell somebody lol. My friends don't appreciate it fully
Here's what I added anyhow:
Went from blah E7s to a set of 40Ps, obviously, TFS dual springs, new pushrods, 1.7RRs and the 70mm MAF. On the old heads the top end felt really slushy and like power would die off where my stock tach read 4,800. Not anymore! Still haven't gotten on it too much, since I'm kinda paranoid that it will develop a lower intake coolant leak. After some more inspecting, I'll take her out again.
Anyhow, the whole swap went pretty damn well! I really didn't run into any problems, didn't spend much money at all, and the actual labor wasn't so bad... so anyone still on E7s (excluding the ported ones, of course) should run to the JY and pick some of these badboys up! They rock.

 

[25thmustang]

Ill stick with E7s, thanks...


J/K we have a GT40P car and it does pull good. Those heads probably helped low end, and made the car feel a lot better on the street!

 

[Mr. Rustypwnz]

youll love the change!!! it feels way stronger from 3-6k, mine likes to spin now and revs fast!!!

 

[85_SS_302_Coupe]

I have some really cool head news on the way.....stay tuned


On and congrats on the Ps, they are some badass stock heads.

 

[1985 5.0]

These heads come stock on the Cobras???? would a set work on my carburated 85??

 

[MAC'n89Blckstng]

I had the same exact reaction when I put my gt40's and Explorer Intake on my car to help the existing e303 cam. And then I put the big mass air on it wow. I can actually pedal out first, makes the hard acceleration sound awesome. Did these heads change the sound of your car at all? Mine got 4 times raspier. Congrats on the install, just think what a set of AFR's would do to our cars.

 

[85_SS_302_Coupe]

These heads come stock on the Cobras???? would a set work on my carburated 85??

GT40's came on the '93 Cobra, GT40P's came on later 5.0s, commonly found on '98+ 302 Explorers. And yes they will work on your '85, i was going to use them on mine but i have other heads now.

 

[Strippt88]

Block's the same, aughta be fine on the 85.

 

[BLOWN 5.0 FOX]

im not too keen on the four eye models but I heard piston to valve clearance on bigger valved heads were sketchy prior to 86...just a half thought, check into it.

 

[1985 5.0]

GT40's came on the '93 Cobra, GT40P's came on later 5.0s, commonly found on '98+ 302 Explorers. And yes they will work on your '85, i was going to use them on mine but i have other heads now.

thanks for the info

im not too keen on the four eye models but I heard piston to valve clearance on bigger valved heads were sketchy prior to 86...just a half thought, check into it.

i thought the 86 was the only year with the piston to valve clearance issue

 

[85_SS_302_Coupe]

Yes, the '86 has no valve reliefs on the pistons....BUT, it's always a good idea to check clearance anyways.

 

[TomCat]

I had the same exact reaction when I put my gt40's and Explorer Intake on my car to help the existing e303 cam. And then I put the big mass air on it wow. I can actually pedal out first, makes the hard acceleration sound awesome. Did these heads change the sound of your car at all? Mine got 4 times raspier. Congrats on the install, just think what a set of AFR's would do to our cars.

Yeah man, it really seems like it. My bro came out and said it sounded different, too. lol, now I'm kinda thinking... damn, shoulda waited and got some AFRs. Oh well, gotta build the car with what money I have
Oh and if anyone is wondering, MAC shorties will work but the #4 plug won't fit without dimpling the pipes... and I stuck a heat shield on there too for good measure.

 

[madspeed]

pretty nice heads for the dough. i had em too. see times in sig!

 

[TomCat]

Right on, more info on your mods at the time? I'd love to hit 11s, but it's so not happening... probably not even 13s, lol.

 

[BigHairyMonkey]

^you should MOST def be DEEP in the 13s with some Ps

 

[madspeed]

i had pretty much all the bolt ons. was running 13.10's at 105 without the 150 shot

 

[25thmustang]

Our 40P car was going 12.00s (on a warm crappy track day) and did go 7.48 (11.7 or so) into a headwind (the reason Etown was shut down to 1/8th passes only). It had a race set up chassis and such, but the motor was very simple. Stock rering on the bottem end, GT40Ps, milled to 58cc, 1.84/1.54 valves with VJ, 1.7 rockers, stock cam, 4 degrees back, Cobra intake, 70mm TB, 76mm MAF, 24 lb inj., K&N in the stock box, underdrives, FMS shorties, Prochamber, and Hooker mufflers out tailpipes. The chassis planted the power, and it didnt have smog, AC or anything of the sorts, but the motor is now in my brothers 86 street car. Were expecting mid 12s out of it (the 3.55s are going to kill it, the old car had 4.30s, but went 12.1 with 4.10s).

Dont be discouraged, the heads arent a $1000 AL piece, but for the money they are great and can be made to run hard! Just ask the right questions, run the right combo, and drive the piss out of it!

 

[TomCat]

Awesome, now I'm all exicted to get it out to the track. I think my next couple paychecks will be going into to chassis stiffening and the like.
Thanks for the responses guys