The only good use I have found for the blue case o-rings is to use on the plug wires to identify the lower set of wires on a twin plug engine. I slipped one on the plug end before I put the boot on and used moroso heat shrink cylinder id numbers and did the same at the distributor end. Blue o-ring = bottom plug. Hows that for simple. If I could just figure out a way to put the cyl # on the o-ring. I will post pics when the proper time comes and I can figure out how to get the pictures to load. $hitty camera?
