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Valve clearance

Joe Jet

Member
Would one want to go for the smaller or the larger valve clearance dimension at overhaul? Seems to me that clearance will get larger over time.
 
Actually the opposite applies. If you have the cylinders overhauled, the valve seats and/or the valves, may need to be reground. This causes the valve to sit lower, effectively making the valve clearance smaller. I personally had to replace the push rod to a shorter one in order to have the appropriate valve clearance according to Lycoming spec.
 
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Would one want to go for the smaller or the larger valve clearance dimension at overhaul? Seems to me that clearance will get larger over time.

Normally as valves "seat" clearance will get tighter, but not by much. Best to shoot for mid-range.
 
Normally as valves "seat" clearance will get tighter, but not by much. Best to shoot for mid-range.

Yep, the heads and case heat up and increase the clearance, then as the seats wear they get tighter - so no need to second guess the recommendation.

Good when hot, good when cold - good when young good when old.
 
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