View Full Version : ? for the small engine guys

J Harp
04-19-2006, 10:53 PM
Finally got the engine I asked about in earlier thread back from the machine shop and got all the parts together. Now I need to know what the ring gap should be. the oil ring has only .004 gap in about the middle of the cylinder, don't seem like enough to me, didnt check the other two rings yet, these are B&S cast iron rings, .020 over, giong in a newly bored .020 over cylinder. Engine model no. is 253702, type 0134-01. thanks.

04-20-2006, 12:40 AM
I think we need the bore. IIRC, it's .002 to .003 per inch of bore.

J Tiers
04-20-2006, 01:48 AM
Book says for standard bore, series 250000, rejection size is :compression ring 0.035, oil ring 0.045. They don't give a minimum.

J Harp
04-20-2006, 02:47 PM
Thanks David and J.

That gives me something to go on, I visited the B & S website and got the external adjustments & specs but didn't find anything to do with rebuilding. I'll check the other rings and see how they look, I'm thinking the rings probably warm up quicker than the cylinder walls since they are smaller mass, and definately don't want them butting together as they warm up, but since the book doesn't give a min. gap this may not be a concern. Wonder what the CI in Al construction does to the actual thermal expansion of the bore.