Board index Flathead Power-Technical Questions, Answers, and Suggestions Knuckles ring gap

ring gap

Post Sat Mar 10, 2012 9:25 am

Posts: 8
I'm putting a 47 el motor together on a new bottom end. Previous owner blew a rod through the case and started a rebuild but lost interest. I have a new set of cylinders, rings, and pistons that I got in the deal. The rings are gapped at .020. My question is that to large a gap? I live in phoenix so it will spend alot of time in the heat. I have already had the bottom end repaired and rebuilt, new pinion shaft, crank pin, sprocket shaft, its all new and true so I don't want to put it together only to pull it down again for something I should do now. Thanks. cc

Post Mon Mar 12, 2012 4:25 pm

Posts: 152
Location: Carver, MN

I would not be worried at all about a .020" ring end gap on a 61" (the manual calls out .010 to .020). Keep in mind that under running conditions, the gaps will close up considerably as the rings heat up. A slightly loose ring end gap is nearly never the cause of excess oil consumption. On the other hand, too tight an end gap can cause the ring ends to butt against each other and break the ring lands of the piston if the engine is run too hot. And since you said you are in Phoenix, I would be double checking the piston to cylinder clearances and adjusting them to more than the minimum for similar reasons. As a matter of fact, if it was me, I would also have ceramic put on the piston domes and a coating such as PowerKote on the skirts to combat the heat keep those pistons happy.

Enjoy your 61!

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