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PostPosted: Sun Oct 23, 2005 5:27 pm
by artman12us
Can someone explain the ring gap measuring procedure. thanks Art

PostPosted: Mon Oct 24, 2005 3:25 am
by ozzie
easy .. take the rings off the piston and place one in the bore as it would be on the piston use the piston and push the ring about one third down. using the piston to push it down will make sure the ring is even in the bore remove piston and with a set of feeler gauges measure the gap. this will show how much ring wear there is. ie biger the gap the more wear, repeat with other rings. back this measurement up by measuring the bore with an internal micrometer. compare these readings to the limits shown in the manual these two readings will show you whether to rebore or just replace the rings. if you don't have a internal mic. take the barrell to a engine rebuilder and he can do it while you wait. measure the bore across the ports as the wear is towards the rotation of the crank.
the bore measurerment is more important than the ring gap on an old engine' if you have a ring gap that is on the limits may not mean that replacing the rings will restore compression. the bore may be too worn. thus still giving the new rings a large gap.
checking the ring gap on a freshly rebored barrell is pretty important. it may prevent a nipup that will score your new bore. if the rebore is a few thou undersized there may not be enough gap on the new rings. so if the gap reads under you may need to file the ring end to open it up a bit.
there is another more accurate way to measure ring diameter and your engine rebuilder can do this for you when he measures the barrell. it takes about 30 seconds. taking your measurements needs good acruacy the first rebore size is usually +.010 thou so do all measurementsa at least 3 times to make sure you get a true measurment
so best to check bore size first and if near the max limits go straight to rebore. if it is well within tolerance check the ring gap or the diameter of ring if the gap is too lge or diameter is too small replace the rings. before fitting new rings first remove the ridge on top of the barrell and give the bore a hone. plenty of good books around to show you how to do this. ozzie