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Old 07-04-2020, 09:04 AM   #4
Ol' Ron
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Join Date: May 2010
Location: Chester Vt
Posts: 8,842
Default Re: 255 merc excessive ring end-gap?

Using the old formula of .004" per inch of cylinder bore, a 3.312 would have aprox .14". I've always used .015/.016 for the top ring and .016/.018 for the second. So.030 sounds quite large, to be considered OK. Unfortunately, I've never given the ring clearance much thought. I was always todl, to littel can damage the piston, so error on the big size. I've followed this rule for many,many engines. so far , so good.
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