Some of my intake valves are sticking open when the motor is cold. I can turn it over by hand with the valve cover off and see some of the intake valves staying open. If I tap on them with a socket extension they snap shut. If I crank the car up the cams will tap them a few times and they will work fine. Even if I turn the motor over by hand a few dozen times they start unsticking. I degreed my cams and they were off, I had to retard the exhaust cam by 6 (cam) degrees and advance the intake by 5 degrees. Would that have been enough to cause the valves to hit the pistons?

Engine specs:

Dart tall-deck block, shaved to 226mm
GSR head, cut to 38cc chamber size, ported, aftermarket valvetrain, .5mm oversized exhaust valves
GE 86mm head gasket
JE 85.55mm 9:1 pistons
Crower Stage 2 boost cams (.460 or so max lift, but they are even sticking on the low lobe, so I don't think that anything is binding)

I did a leakdown on #4, which has the worst valve sticking problem, and it was at 3% (with the valves shut), which is leaking past the rings, nothing out the intake, which is what I would expect if they were bent.

This head has maybe 300 miles on it and just started doing this over the last couple of days. the motor has about 100 miles on it. After a second or so of sticking when I first start it cold, everything unsticks and it runs perfectly, no smoking, backfires, nothing.

I'm thinking of removing the springs on the sticking valve and see if it is binding when I slide it by hand, but I can't think of anything that would cause this behavior.

 

Damn, nobody?

 

??? idk man, hella weird

 

hows the valve guides? just throwing something out there your a pretty smart guy so might be one of those weird one off problems.

 

thats the track i was thinking too? but what would have changed

 

Yeah, that's what I'm wondering, it worked fine for 300 miles, so what did I do different?

 

so all of a sudden this problem popped up? did you notice any foreign particles in your oil?

 

oh i didnt read your full post, you degreed the cams they were off a little bit, did you notice any more drag when turning the motor over or did it rotate just as smooth? is it possible your piston/valve clearance might have slightly bent the valves just a little bit as to where they drag in the guide?

 

It turns smoothly by hand, I'll pop the springs out whenever it stops raining here and see how smoothly the valve moves in the guide. Normally when I bend them they don't seat properly though, and I'm not getting any leakage out the intake.

 

i see yeah leakage would be the first sign weird problem your having usually its pretty clear cut case but i might take a little farther looking into.

hows that supercharger project coming along?

 

Almost done, got the mount and tensioner put together, need to finish the flanges and get the manifolds made.

 

cant wait for the results, what weight oil do you run?

 

10W30

 

pretty standard, well see when u remove the valve springs and check the movement.

 

Did you adjust ur valves after assemble, If they are tight for some reason the valve will be stuck open.

 

It's carbon buildup on the valve stem. I took the springs off of a couple of intake valves today, one sticky one and one non-sticky one. The non-sticky one moved up and down easily by hand, the sticky one required pliers and a lot of effort to get it to move. I pulled the seal off of it and there were chunks of carbon under the seal around the valve stem. I blasted it with a shot of brake-clean and the valve freed right up, slides smoothly and easily now.

BTW, what is the proper tool or tools for removing and installing valve stem seals? Based on the mangling that I inflicted on mine, I'm guessing that a pair of pliers and a 10mm socket were not the technically correct choice.

I ran some Sea Foam through it and tossed some lifter unsticker oil in the gas tank, I'll see if that does anything, but I'm guessing that I'll have to pull all of the seals and clean them up individually.

 

snap on, or mac tools, have some cool round tipped pliers that work pretty well

 

http://buy1.snapon.com/catalog...talog

 

the head has carbon buildup already with 300 miles. you could have not spun the motor up high enough (rpms) to rotate the valves. At least above 3,500 rpms

 

Marvel Mystery Oil FTW!

I'm not a big fan of oil or gas additives, but I figured I'd give a few ounces in the gas tank a try. After 20 miles of driving they freed up. I put about 70 miles on it and pulled the valve springs, the valves all move freely by hand.

 

ya, we mix marvel in all of my race gas

 

It's running great now, just made 197 NA with it, not bad for a 9:1 B-series. I'm getting it ready for VIR next weekend.