Explorer GT-40 heads a direct bolt-on?

[DucatiRdr]

I picked up a decent set of heads from an early 1997 Mercury Mountaineer. I removed all of the plugs including the one that was rust welded in place and am now in the process of finding a good machine shop in the Metro-north Boston area to do what needs to be done to make these ready to bolt on my 1988 5.0.

I did a lot of reading before picking these up and I remember reading that these need to be milled to be the same specs as the 1993+ Cobra heads. Is this true?

I plan on port matching these to a set of FRPP intake gaskets and cleaning up the ports in general. Besides that:

1) The Mountaineer had 65K on it and I guess the junk yard pulled the engine after the woman owner hit something that poked a hole in her oil pan. The junky told me the SUV was shut down before it siezed, but was parted out because a new engine was swapped in. The valves don't look like they were overheated, but they are still mounted in the head so I don't know what the seats look like. Assuming the valves are in good shape, should I clean them up and reuse or replace them with FRPP stainless bits? When I had head work done on my Ducatis I was recommended to keep the OEM valves as they would have the best durability and I am assuming the same holds true here.

2) Tmoss recommended I upgrade to Comp Cams #978 springs to match my OEM cam and FRPP 1.72 roller rockers. What valve keepers should I buy? Spring retainers?

3) These heads have some scale rust on the outside and look like they could benefit from some time with a wire wheel. Should I get these "hot tanked" or is the wire wheel treatment sufficient?

4) Anything I missed?

 

[Mr. Rustypwnz]

they will bolt right up, but they need a special header, the frpp p headers will work as well as the mac p headers, and bbk long tubes will work as well, stock wont though. Get some valve springs as well as these springs are only good for like 450. I would go with the kit tmoss said. They dont have to be milled, they actually flow better than the gt40 cobra heads. The hot tank deal, I believe is just a personal oppinon, I would clean em up, just check for cracks and make sure they are good.

josh

 

[DucatiRdr]

they will bolt right up, but they need a special header, the frpp p headers will work as well as the mac p headers, and bbk long tubes will work as well, stock wont though. Get some valve springs as well as these springs are only good for like 450. I would go with the kit tmoss said. They dont have to be milled, they actually flow better than the gt40 cobra heads. The hot tank deal, I believe is just a personal oppinon, I would clean em up, just check for cracks and make sure they are good.

Hey Josh, thanks for the reply!

These heads are the straight GT40s, not the GT40ps.

How about the valves? OEM vs. FRPP stainless?

Thanks!

 

[DucatiRdr]

Anyone got a link to a thread that already covers these topics? My search skills stink!

 

[innes]

I have a similar question I got my GT40s of a 97 explorer to (not “p”). They are part# F3ZE I already had .010 milled of and I was wondering if I should take more. Trying to get compression up there

 

[Mr. Rustypwnz]

The valves are your decision, I was going to do the p heads but now that i know that they only hold 450 lift, im kind of scared!!! so im going the straight gt40 route now. I dont know about the milling thing.

 

[ninety15.0]

I had the same questions as you have. I got regular iron gt-40's and had them milled 20 or 25 thou to get the compression back up some. Stock valves (New) but everything else (seats, spring perches, new seals, 3-angle, shimming) was done at once and hot-tanked. I used the comp cams spring kit, i think they are double coil springs with a damper and I think the stock gt-40 valvtrain included a rotator on the exhaust spring/keeper that i no longer run... I would say that its easier to spend a little more money up front to do everything right the first time, and keep the CR up and make a real nice valvetrain setup.

 

[DucatiRdr]

Ninety15.0,

Thanks for the reply. Was there a difference between the GT40 and e7 compression ratios "out of the box" or did you mill the heads to increase compression?

 

[ninety15.0]

I think the combustion chamber size on a stock E7 head is around 59cc....and the size of a regular Gt-40 is 63.5 i believe. That difference effectively lowers the CR by about 1 point from 9:1 to 8:1 with stock pistons. I cut the heads to raise the CR back up by just under 1 point and im running SRP pistons @ 9.8:1. So i figure im right about 9.5:1 and i like the compression for a street car. I would say though...spend as much as you can afford on the proper machining as well as rockers, lifters, push rods, and hardware b/c its way more reliable....and its easier to make effective power. good luck

 

[jrichker]

Mill the heads more than .030 or so and you will probably need some pedistal shims to go under the rocker arm mounts. This restores the valve train geometery to the proper angles.