Piston Ring Groove Spacers

Pistons should be replaced when the ring side clearance to the ring land is excessive. On older and obsolete engines it is not always possible to obtain new pistons at a reasonable cost.
The time proven solution is to re machine the ring grooves out 30 thousandths wider and install a spring steel spacer on the top side of the ring. This restores original new clearances and allows full compression to be restored. Since the top grooves always wear the most many times they alone need to have spacers installed. Sometimes where excessive wear is present all compression grooves need re machining and spacers installed. Oil grooves would rarely need spacers since they will still scrape oil if side clearances are slightly out of spec. See the illustration above for what a typical spacer installation looks like. Spacers usually hug the lower portion of the ring groove and do not touch the cylinder wall. Spacers must always be installed on the top side of the compression rings. They actually become part of the piston. Thus original size and type rings can be used so that stock performance can be maintained. Sometimes a wider ring can be used instead of a spacer if it is a common size. A wider ring will make a little more friction but not enough to be a problem.
Spacers are available in most diameters from 2 1/2" thru 5". Also available are 5 1/4", 5 1/2", 5 7/8" and 6 1/4". Occasionally .025" chrome oil ring rails can be used for some of the diameters not available as spacers. Spacers are reasonably priced at $4.00 each for up to 5" sizes and at $6.00 each for 5-6" sizes. Shipping and handling extra.
Contact us for technical assistance in installing spacers or wider rings. Sometimes the ring grooves must be deepened to allow proper clearance of some spacers. Please note that the ring grooves must be machined in a lathe to straighten the grooves and assure proper fits.
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