DennisC6

Could some one tell me all the need to knows about gt40p heads like compression ratio, what the timing should be set at, ect? help would be appreciated!

AdderMk2

CR will raise to about 9.4:1, and the heads done determine your timing.

my83tbird

I read, using google and ebay people selling the heads it rates @ 9.0:1 compression timing I'm not sure don't forget the GT40P was used in 96-01 Exploders and Mountaineers Vin. P casting# F77E-AA. Ignition systems on these vehicles are DIS. the PCM controls the timing. My Alldata reads 97 Exploder w/5.0 is set @ 10 deg. BTDC & non-adjustable.
hope this helps

jojobanks

what heads do you have now? need to have a casting # off your current heads so we know how big of a combustion chamber you have.

what type of gt-40 heads are you planning to get? There are different gt40 heads with combustion chambers ranging from 58cc to 64cc. If you get a set of heads with a bigger combustion chamber than the ones in your heads then it will lower your compression

TrimDrip

timing is discovered at a track.

my83tbird

I bought a 89 5.0 HO motor to replace my 83 T-bird motor. The 89 casting# E7TE on both the block and the heads, with TRW E7ZE-6110-CA valve notched flat head forged pistons. Its a normal smog motor.
I found a nice set of 97 GT40P heads off of a wrecked exploder. I guess they forgot to change the Firestone tires. I plan on using Crower 7 deg. +0.050 ht. valve stem locks part# 86107X1-16 @ crower.com, compcam beehive valve springs part# 26986-16, compcam 7deg. valve spring retainers part# 787-16, @ compcams.com while using the stock 1.6:1 rocker arms. This should give me enough distance between the bottom of the valve spring retainer and the top of the valve guide seal to avoid over compression of the spring without any machine work to the heads. I found a few cams that might work but unsure of, to avoid piston to valve crash.

Comp Cams
35-308-8 lobe separation 114 deg. valve lift 0.533 in/exh duration @ .050 lift 210/215

35-349-8 lobe separation 114 deg. valve lift 0.512 in/exh duration @ .050 lift 212/218

35-320-8 lobe separation 112 deg. valve lift 0.544 in/exh duration @ .050 lift 212/218

Crower Cams
15510 lobe separation 114 deg. valve lift 0.531 in/exh duration @ .050 lift 212/212

15520 lobe separation 112 deg. valve lift 0.480 in/exh duration @ .050 lift 210/214

My question is will these 97 GT40P heads on the 89 HO motor??
If anybody has any other suggestions or ideas I would appreciate any & all inputs.
Thank you

jojobanks

@my83tbird

My queston was to the original poster. I'm guessing you don't know forum etiquette, but it's considered rude to hijack another poster's thread with your own questions.

That said, I can't really answer you anyway. The valvetrain you mention sounds pretty solid and should handle your cam with no trouble, but as far as piston/valve interference you'll have to check that yourself. I will tell you that the gt40p heads have a slightly larger intake valve so you may end up having to cut into the piston valve reliefs for extra clearance.

AdderMk2

Your information is very incorrect.

A stock 5.0 HO will run right around 9:1 CR, that is with the normally 62-64cc combustion chambers found on the E7TE heads.

GT-40P heads have a 58-59cc combustion chamber, netting an increase in static CR to about 9.4-9.5:1

Explorer GT-40 heads will normally have a ~66cc combustion chamber, and will generally drop the CR of a stock 5.0 HO to around 8.8-8.9:1

Also, 96-97.5 Explorers did not run F77E heads. Those heads began production in 1997 and were available on 97.5-01 explorers. They are GT-40P heads.

StalkerGT

i plan on getting gt-40 heads...what year explorer should i get them off? i have a 90 gt. Are the GT-40p heads better?

AdderMk2

did you even read my ****ing posts? Better yet, did you search?