Valve seal/spring failure

[pcdrj]

If the valve spring didn't fail in his engine, a worn valve guide can contribute to valve breakage since a worn guide will allow the valve to wobble slightly as it opens, which cause it to drift off-center with respect to the seat. This can cause the head of the valve to flex slightly each time it closes. After so many cycles, the metal fatigues and the head of the valve breaks off from the stem.

This motor had maybe 4 hours on it so wear was not an issue. The broken valve was fractured as a result of exceeding the material's tensile strength caused by collision with the piston. The break was clean and sharp. Metal fatigue would show more deformation along the fracture area.

Again, we think the valve stuck open due to material buildup on the shaft from the I/C. If that hadn't happened we probably wouldn't have known about the grooves in the seat until there was a failure there.

What guides are in the heads and what valve-guide clearance was used? Also, do you know what lash clearance was used?

Getting this info this morning.

 

[pcdrj]

What guides are in the heads and what valve-guide clearance was used? Also, do you know what lash clearance was used?

Stock guides with .002"-.004" clearance. Lash is zero clearance.

 

[FlyByNight]

I'm thinking the heads are getting to hot and the valve seized in the guide. Don't know what to say about the valve seal wear.

 

[US-1]

Stock guides with .002"-.004" clearance. Lash is zero clearance.

Stock guides don't like aftermarket valves. At the very least they need a bronze liner and .002 clearance. Zero lash will give you valve-piston problems every time.

 

[FlyByNight]

I had a 66 Fastback seize a valve and do the same thing. It wasn't a clearance or oiling issue, the engine had a ton of miles on it, the head got to hot.

 

[FlyByNight]

In my situation the coolant passages where plugged up, in the OPs situation I'm thinking more on the lines of the supercharger causing to much heat or maybe he's running to lean.

 

[SD07GT]

I Would like to see who this well know builder is ? any bets ?

 

[pcdrj]

Stock guides don't like aftermarket valves. At the very least they need a bronze liner and .002 clearance. Zero lash will give you valve-piston problems every time.

I think the factory guides are PM. The Ferrea Superalloy is some high nickel allow (they state it's not INCONEL) so based on dissimilar metals I wouldn't expect to get any galling but bronze would definitely be better. The system is hydraulic which, I thought required zero lash. What clearance do you recommend?

 

[FlyByNight]

Looking at this picture I guess it's more likely that a valve got bent, I'd be pissed!

 

[FlyByNight]

Looking at this picture I have to wonder how those big ass pieces made it that far? Is this one of those stupid ass FAIL threads?

 

[Shat9611]

thats weird that a heat exchanger debris would make its way up to where the valve seal is causing it to fail but i suppose crazier things have happened, also when you first realized there was a lose of compression in one cylinder you probably should have done more investigating then instead of just assuming the metal would work its way out of the engine just my 2 cents, but i am curious to see what you find out was the true smoking gun

 

[FlyByNight]

Deleted....

 

[US-1]

I think the factory guides are PM. The Ferrea Superalloy is some high nickel allow (they state it's not INCONEL) so based on dissimilar metals I wouldn't expect to get any galling but bronze would definitely be better. The system is hydraulic which, I thought required zero lash. What clearance do you recommend?

.015"-.020"

 

[Gray Ghost GT]

Do you feel confident, based on the cam cards you were given with your new engine, that the COMP Cams custom grinds were VSR and not SPR since you weren't running phase limiters or lockouts? I'm wondering how much PV space you had while at the high RPMs you see on the road courses with the custom cams.

 

[lito]

Did you finally found who makes those seals? Felpro maybe?

 

[toorbeenee]

Did you finally found who makes those seals? Felpro maybe?

when i got the springs from livernois they looked exactly the same

 

[lito]

Surprise, surprise.

 

[hamish]

Those are the Fel-pro's aren't they?

 

[redstangs9308gt]

well who built the motor?

 

[lito]

Those are the Fel-pro's aren't they?

No, they are done by another company.

well who built the motor?

This came with new Livernois stage 3 heads, 700 miles after.

I've only removed one because I don't have the proper compressor for aftermarket springs.