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Discussion Starter · #1 ·
I have a 90 GT on which I just performed a head swap. I'm now running GT40 irons (milled .010), and the car had Cobra Roller Rockers on it (which I discovered on the E7s when I took it apart). I had the heads rebuilt with the Trick Flow kit, but used FRPP valve stem seals because I read a few posts saying the TFs can cause problems.

The valve train geometry kicked my butt for longer than it should have. I first tried to put the engine together using stock length pushrods, and when I went to start it, I could immediately hear excessive clicking (I didn't torque the rockers properly). I shut the engine off, took everything apart, remeasured the pushrods, and came up with 6.300". Ordered TF pushrods, put them in, used a marker on several of valves, and the geometry was about as close to perfect as I was gonna get without special ordering 6.315 pushrods. I called it good, had to use shims on most of the rockers with the majority torquing to 18 lbs. in between 1/4 to 3/4 turn, put everything back together once again, and started it up. The roller rockers sounded fine, but I determined I had a vacuum leak at the back of the intake manifold.

So this morning I took everything off again with the intention of using silicone instead of the cork gasket on the intake. I didn't wanna drain the radiator and have to spend another 20 bucks on antifreeze, so after I pulled the intake, of course some water got into the lifter valley. I got a roll of paper towels and began soaking up the water. While doing so, I noticed tiny pieces of what I'm almost sure, are my valve stem seals. I seriously wanna kill myself.

Any suggestions as to what I did wrong? I DID feel confident I had the valve train geometry correct, but fragments of valve stem seals seems to suggest otherwise. Are there any other reasons why this would happen? Thanks in advance.
 

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Too much valve travel or the seals are too big around for the inner spring damper. What cam are you running with the 1.7's?
 

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Discussion Starter · #3 ·
I wish I knew what kinda cam is in it. But the previous owner is dead so I have no way of knowing.

By valve travel, you mean the distance the valve is moving due to the 1.7 RR's and the cam is too much? So maybe going with stock rockers would cure it? What messes me up is, the car was working fine (aside from a blown head gasket) with the current cam, RR's and E7's.

The guy I took the heads to came highly recommended, so, I've just been assuming he did everything correctly and the error is on my end (which I'm sure it is). I am so pissed I'm gonna have to pull those heads again. I thought I was practically done. What a nightmare.

(I'm sorry, this is my first head swap, so I'm in a little over my head on this & still trying to learn.)
 

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Discussion Starter · #4 ·
So I guess the thing to do is replace all the valve stem seals, lose the RR's and go with the stockers? I mean, surely that would work, right? At this point, I just want the car running again. I'm not too worried about the 5 extra horses I'd get from the roller rockers.
 

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You can measure the lift with a dial indicator. I'd pull a spring off and get a new valve guide seal and see if the spring fits over it without rubbing.
 

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I wish I knew what kinda cam is in it. But the previous owner is dead so I have no way of knowing.

By valve travel, you mean the distance the valve is moving due to the 1.7 RR's and the cam is too much? So maybe going with stock rockers would cure it? What messes me up is, the car was working fine (aside from a blown head gasket) with the current cam, RR's and E7's.

The guy I took the heads to came highly recommended, so, I've just been assuming he did everything correctly and the error is on my end (which I'm sure it is). I am so pissed I'm gonna have to pull those heads again. I thought I was practically done. What a nightmare.

(I'm sorry, this is my first head swap, so I'm in a little over my head on this & still trying to learn.)
U don't have to pull the heads to change the Valve seals. U simply pump air into the cyl, remove the spring, reinstall seal, springs, keepers & move on to the next one. Been there a number of times...
 

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I would take pictures of the valve stem seals and spings while together on the head and post them. Then turn the engine over by hand while whatching the valves open and close. Make sure the valve stem seals are staying on the valve guide and not moving at all, if they are the positive lock style. Also check to make sure the bottom side of the spring retainer and or valve locks are not hitting the top of the valve stem seal at peak lift or not coming close to hitting. Then make sure inner spring or damper spring is not making contact with the outer part of the valve stem seal. There are many different valve stem seal sizes and styles. There are both positive lock and umbrella seals. The positive lock seals fit tight on the valve guides and may require a small plastic tool to install depending on style, some are a rubber with a spring steel collar to hold them on, some are a nylon with a spring steel collar, then some have a steel shell with rubbe vucanized to the shell. The lastly you have the old rubber umbrella seals that are supposed to go up and down on the valve stem. Also there are multiple diameter valve guide out side diameters, so if you are using positive lock seals, you need to make sure you have the right diameter valve stem seal. Lastly did you use the clear plastic tube over the valve stems to protect the seal as you installed the seals? You should have also used a lube of some form on the valves.
 

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Have you looked to see if the valve stem seals are indeed chewed up? Someone mentioned it but you can get a tool that screws in where your spark plug goes and use an air compressor to pressurize that cylinder. Then you can take the valve springs off without the valve falling down. It could be the seals are too tall and being hit by the retainer or too large in diameter and being hit by the inner spring. BUT, you'd also have pieces of rubber in the heads especially around the drainback holes. If you don't have any around the valve springs or drainback holes it's not your seals.

And if it was the cork seal leaking on the back of the intake, that's not a vacuum leak...just an oil leak. Ditch the cork or rubber gaskets. Do a test fit with your intake and see how large the gap is. Lay a bead of rtv across there at least 1/8" taller than that gap. Let it skim over. Put your intake on and MAKE SURE it compresses that bead. If it does, torque the intake and DON'T TOUCH the silicone...even if it squishes out. Don't run your finger down it...don't trim it with a razor...just leave it.

I've always seen it leak if you mess with it and not if you just leave it squished out.
 
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