[leon bee]

Originally Posted by frnkeore

The reason for end gap is expansion of the ring, per inch, per degree.

The top ring runs hotter and needs a little more gap than the second and oil ring.

I don't know the alloy of cast iron rings but, the expansion ratio of gray iron is, .0000058. The circumference of a 3.217 bore is, 10.1035 - .018 = 10.0885

10.0885 x .0000058 x 300 deg = .01755. Not quite touching but, if the ring gets to 350 deg (say a severely over heated engine), it will touch and need a .020+ gap or it will butt together and possibly break.

The 46/48 spec is .014 and I think .016 would be great in a street car that gets reved a lot, on the street, .018 for race and .020 would be fine but, .032 is to much.

The .040 rings should be fine after file fitting.

Frank: Contemporary thought, (I read a lot) seems to suggest the second ring gap should be larger?