Quote:
Originally Posted by CLV8
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The racing engine specialist talk to me about all possibles issues but for him it's a valve guide problem or a too high valve lift causing premature guides failure.
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This is one example of the questionable information / guidance the engine specialist is providing you OliveR.
Lift will not wear guides. A valve stem and a guide are a linear bearing. Small displacements or large displacements have no lateral thrust in a linear bearing. Too much lift can bind springs or introduce spring retainer to guide interference but importantly, it does not put a side load on the valve stem. Side loading comes from incorrect rockers, poorly installed rockers, just bad rocker geometry in general or wrong length pushrods to hit the most common contributors. All of those contributors can individually put a side load on a valve stem that will accelerate guide wear but importantly, lift will not.
I suspect your engine specialist while presumably well intentioned is unknowingly providing you an inaccurate analysis of why what has transpired, transpired. As well intentioned as he might be, I doubt he will be able to either solve or fix the problem, primarily because he does not understand the origins of the problem.
There was a popular Indiana Jones movie a number of years ago where Indy was searching for the Holy Grail. He and the bad guy find it almost simultaneously. The problem is, it is only one of a number of Grails on a table before them. The bad guy chooses the grail he believes to be the True Grail and fills it from a water source in the cave and drinks the water from the grail. He promptly dies and turns to dust on the floor of the cave before everyone's eyes.
The Knight's Templar, Knight who has guarded the Grail for centuries turns to Indy and offers a simple admonishment, "Choose wisely. He did not!"
I am going to offer the same admonishment to you for your consideration. Choose wisely. You won't die if you do not but, your engine might.
Ed