COMET CENTRAL

That's great, I believe I have the Cobra 1.7's since they are Cobra head's. I'll PM you my address.

SW

Sorry to hear this. That's got to be frustrating. I am a little confused slightly but it sounds to me that some one has rebuilt your motor with non-H.O pistons and haven't accounted for the different compression height on the newer motor. I am lost on the trouble with the springs and seals. What I have is a 97 explorer motor which should be the same as yours except your heads being milled for higher compression from the factory, and I purchased a trick flow stage one cam and the whole spring and seal kit. It all worked flawlessly including just pressing the new seals on the previously existing guide towers. Hope that helps!

The GT40 head has two different spring height's and 2 different retainer's. The set from Alex's has equal spring sizes with different keeper's for intake and exhaust. The spring installed height's were very consistent very, very close to optimal. According to my engine building friend, he has seen these piston's from Ford. He said he thought they were chasing emission reg's. And from what I've gathered the 93 block component's changed again in 94. Damifino.

Yes they used them in the non ho motors. 87 to 93 they were forged and after they weren't which is what I have but they still should have the reliefs if it was a mustang motor. Just trying to give some insight. Ya my trick flow springs have are different in length but I all add a very accurate install height and had equal shims from which they provided. Hope you get everything figured out! They're a fun setup!

I don't know about GT40 heads having two different spring heights. The cast GT40 heads that came on my 5.0 crate motor were supposed to have special high performance springs, retainers, rotators and top washers. Plus the stainless valves and better seals. The whole setup was supposed to be better than a stock head. Somewhere i have a document that details all of that. I do have an FMS catalog that lists all the valve and valve parts supposed to be on that head. In essence the springs are supposed to higher rated than stock springs for better closing and less likely to valve floats at high rpms. And the parts are supposed to be more durible.
Ron

I think the 'Stang motors used forged pistons through '92, then went hypereutectic for all '93 & up 5.0's ('Stangs for sure). The non-HO 302's were cast and most (all?) didn't have valve reliefs. '86 'Stang was the same type piston but forged. I'd do the same and cut the reliefs. Crazy that somebody would rebuild a motor and use 'em...!

I'd check deck clearance though. You never know...they could be <1.6xx compression height parts!

Ron - Valves with different stem-height lock locations. The exhaust valves used a rotating retainer, as you mentioned... They were intended to help cool the exhaust valves...worked but they're heavy as $&@#.

A couple companies offered springs for the stock retainers but I don't believe they're still available (could be wrong).

Yours being a GT40 crate motor, the springs might be decent, but all the 5.0 Explorer GT40 and GT40P springs are unsuited for anything but the stock Explorer cam.

Rocket989 wrote:Ron - Valves with different stem-height lock locations. The exhaust valves used a rotating retainer, as you mentioned... They were intended to help cool the exhaust valves...worked but they're heavy as $&@#.

A couple companies offered springs for the stock retainers but I don't believe they're still available (could be wrong).

Yours being a GT40 crate motor, the springs might be decent, but all the 5.0 Explorer GT40 and GT40P springs are unsuited for anything but the stock Explorer cam.

Are you saying GT40 heads used two different stem heights on the same or different heads? As far as I know the valve stems are all the same on mine. Don't have any pics of the valves without the rockers installed but even those all look the same.

Mine should have the special rotators. Never thought they were for cooling just to rotate the valves for longer wear. But that would sure help to keep them cooler. How much heavier could they be? In my case it wouldn't matter as mine never sees any high rpms.

Don't know much about the GT40P heads all I know is mine is was supposed to built with all the good stuff. May not be the greatest heads but I can't complain for my way of driving.
Ron

Tip length is different. Basically the locations for the valve locks are different on the stem of the intake and exhaust valves. All the E7, GT40, and GT40P heads used the same retainer design though there were minor differences.

Rocket989 wrote:Tip length is different. Basically the locations for the valve locks are different on the stem of the intake and exhaust valves. All the E7, GT40, and GT40P heads used the same retainer design though there were minor differences.

Here's a pic of mine tried to get it downloaded last night but got too late. As you can see the rockers are the same heigth on all valves on mine.


Ron

Uh, the rockers would sit level....the valves are the same length. The lock location is different on intake and exhaust valves e.g. different "tip" lengths...

Rocket989 wrote:Uh, the rockers would sit level....the valves are the same length. The lock location is different on intake and exhaust valves e.g. different "tip" lengths...

Ok you are saying the the retainer grooves are a different heigth on the valve stem but the valve length is the same? The rockers do look level on mine but then the tops of the rotators look to be the same heigth as best I can tell in my pics. The rotators do look slightly different between intake and exhaust valve. Maybe the notches are different and the retainers are just different that makes them look the same. I think they are called 7* (degree) notches.
If I ever have reason to pull the covers I'll take a closer look. Not going to pull them for no reason. Never noticed any differences when I was installing the roller rockers which has been a few years ago while it was still hanging on the engine stand. Just looked good overall!
Ron

Correct - grooves for the locks are at different heights on the stems.