for about the first 30 years we built engines with the top ring gap set at slightly larger than the second ring gap because it operates at higher heat levels, usually the top ring gaps were set at a minimum of 4.5 thousands per inch of bore diam. and the second ring gap, at a minimum of 4 thousands per inch of bore diam.
BUT RECENT TESTING HAS CONFIRMED
that pressure that bye-passes the top ring that gets trapped between the first and second compression rings tends to significantly reduce the top ring seal, thus the current recommendation is for the second ring to have a slightly larger end gap to significantly reduce that potential.
read thru this link
viewtopic.php?f=53&t=2837&p=7342#p7342
you may want to keep in mind that once an engines up to operational temperatures, the piston to bore clearance is rather tight and the ring gaps are significantly reduced due to heat expansion, in the metals, at just 1000rpm idle speeds , theres 8.3 compression /power strokes PER SECOND, and that almost all the peak cylinder pressure is incurred during the upper 2" of piston travel, as the piston approaches or recedes from tdc, theres not a great deal of the cylinder volume that can leak past a properly functioning ring thru a gap that's maybe 12 thousandths wide, in the .07 of a second that peak compressions potentially occurring, speed the rpms up to 6500rpm and your down to only .011 seconds per power stroke in the higher pressure range, again, a minimal ring gap has almost no effect, everything , Ive read states that gaps up to about 45 thousands of an inch have a minimal effect on compression or power, or even oil consumption if the rings are sealing to the bore effectively.
you'll be far more concerned with the ring seal, bore hone, and having the block honed with plates simulating the bore stress tightened head bolts produce to reduce ring blow-bye
read this
viewtopic.php?f=51&t=588
