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Old 02-14-2005, 02:45 PM
Banyan Day Banyan Day is offline
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Lightbulb Valve adjustment

I've noticed that there is no mention of regular intervals for valve adjustment in the Moyer Manual (..or did I just miss it...). I'm curious; should I be checking valve clearances regularly? Is this easily done on the A4? I have notice some tappet noise which I'm sure is normal, but was wondering.....
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Old 02-14-2005, 07:53 PM
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Don Moyer Don Moyer is offline
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You ask a very relevant question.

Neither we nor Universal (to the best of my knowledge) have ever established a routine time interval for checking valve clearances. My best guess is that poor access would preclude removal of the valve cover on approximately 75% of the Atomic 4 fleet, let alone getting in to actually adjust the clearances if you were able to remove the cover.

Fortunately, clearances on mechanical lifters tend to become somewhat larger as engines age, and you might begin to hear several of the valves start to tap. As you point out, a little tap is not only normal, but actually healthy, at least compared to a valve tappet that is set too tightly.

Valves in an Atomic 4 that may have had their clearances set to too tightly (even for several seasons) have an amazing ability to "heal" themselves if their clearances are readjusted conservatively to the high side of normal. For this reason, if compression has dropped below 60 psi or so in a particular cylinder and the rest of the compressions are OK, we do sometimes recommend going through the struggle of checking and adjusting valve clearances as a last resort to pulling the engine (even if it means removing the manifold to get better access to the valve cover). But as long as compression is normal (85 psi or better) and the engine is performing well, I see no particular value in checking valve clearances.

Best regards,

Don Moyer
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