Spark Plug diagnosis

[Lothar]

Last year, I had a mis-shift that resulted in a slight overrev. I'm not sure that I even let the clutch pedal out all the way. Although the car pulls very strong through the rev range and does not run rough in the lower range, I am still worried about one particular exhaust valve. After performing a valve adjustment, the #3 exhaust valve may have been a bit loose. I know that if a valve is bent, there would appear to be some excess valve clearance. I am probably being paranoid, because the valve adjustment was done on the clock and not due to excess valve noise. #3 was the only valve that seemed out of spec.

If a valve was slightly bent, I assume there is no way that it could close completely. If that were the case, would the spark plug exhibit some sign. The plugs all look the same with slight black carbon deposit that is completely dry (no oily residue).

Should I have a leakdown performed if there is no other evidence. Am I just being paranoid? I don't have racing springs but I do have titanium retainers.

[Rich Walton]

I recommend doing a compression test first. Compare the cylinders to each other. They should all be within 5-10psi.

[SteveBorelli]

Ciao Lothar,

I think you are paranoid (like me ... ;-) )
In my ignorance I don't believe that a "slight overrev", on a well tuned engine, can cause a valve damage.
A valve damage (exhaust) bring rapidly a spark plug to be very different from the others; if you already checked that I think you have not any kind of trouble.
If you persist to be stubborn then do a compression test as Rich suggested, then... Enjoy your Porsche !!!

See ya !

Bye.
Steve

[Lothar]

Rich and Steve,

Thanks for the advice. I was scared to death nearly a year ago when the mis-shift happened. I guess I still haven't gotten over it. Good thing is, it didn't affect my driving.