I need to know what the minimum ring gap should be too prevent damage and other problems. I purchased new std. size rings from Briggs and the oil ring has an end gap of 0.008 in. the top ring is 0.012 in and the middle ring is 0.019 in. This seems like a large variation in the end gaps, and the oil ring seems too tight. Does any one know what the allowable tolerance is, and is this variation normal? I read on a site for a Chevy engine, they said 0.004 in per inch of piston dia. this works out to 0.012in since the bore is 3.454 in. would this be true for a small engine as well?

I don't have my Briggs manual handy, but I seem to remember the reject size for the piston ring end gap to be 0.030". Personally, I would try to keep all the end gaps between 0.005" and 0.015". Anything beyond this and you will start burning some oil.

There shouldn't be that much variation between the rings if this is a brand new set of rings. You shouldn't notice more than about 0.001" difference between them. Are you sure you are seating them square in the cylinder before you try to take measurement? Also, are you sure that you are measuring the cylinder and not the ridge at the top of the cylinder?