What is the ring-gap size for std 302?

  • Sponsors (?)


5ptslow said:
what size is it? and do you also file down the oil rings? :shrug:
have not put a motor together in a long time. thanks for the help

The oil rings are usually pre-fit, as long as you order them for your bore size. Gap the compression rings at 0.016-0.018 for a 4.00 bore, 0.018-0.020 for a 4.030 bore. Go about 2-4 thousandths bigger if you plan on running boost or nitrous.

The rings you get should come with directions on what to gap. My Speed Pro rings actually called for a larger gap on the second rings, which is opposite of what the rule has always been. They say a larger second gap lessens pressure build up between the two, making it less likely to lift the first ring off it's land. I just gapped both at 0.020".
 
The reason for gapping your rings is because the heat makes them expand. You have to have clearance between the ring ends to make room for this expansion. If the gap is too wide, it will hurt your compression and may make oil consumption an issue. If the gap is too small, the ring ends will butt into each other and gouge your cylinder wall, which, of course, isn't good. It could also make your ring break because of the pressure.
 
5ptslow said:
well i put the rings about 1 1/2 inches into the bore and put a feeler gauge in the gap and i got .029 is this correct? or do i need to file em? oil ring seems way over sized.

Did you use a piston to push it down in? This will make sure the ring is square in the bore for an accurate measurment.

Oil rings don't have to be as precise as the compression rings. I think Haynes calls for no more than 0.055 for the oil rings. Or are you saying the rings need to be filed. If so, just file them.
 
5ptslow said:
well i did put them in square with a square :D and the reading i got was .029. so i guess im breaking out the file.
so i need it to be .050 to .055

Your talking about the gap on your oil rings, right? No no, 0.055 is the max allowed. 0.029 is perfectly fine for oil rings.

Instructions with my Speed Pro rings.

TOP RINGS
0.004 for every inch of bore size (ie: 4.000 bore= 0.016")

SECOND RINGS
0.005 for every inch of bore size (ie: 4.000 bore= 0.020")

OIL RINGS
snug fit.

The oil rings don't take as much heat as the top two, so gap isn't as critical. I would say you would want it anywhere from 0.015-0.035.