Mushroomed valve stems

[Bryan_Cotton]

@Bryan_Cotton

I think this is a sign of too much valve lash.

Related post:

Valve adjustment - chromoly pushrods

I was talking to a VW guy at Airventure and he mentioned that chromoly pushrods should be set to a “loose zero.” Basically meaning no lash but you can spin them easily when cold. He said that the original VW pushrods were aluminum which expand a lot, and the chromoly pushrods don’t expand nearly as much. The problem, he said, is when hot that 0.006” lash can grow to 0.018” and that is why people are breaking valve adjuster feet. If you have stock or aftermarket aluminum pushrods then use the…