Ok after finding that I had a miss in this 1970 60 hp at first I thought it was fuel problem so I rebuilt the 3 carbs, adjusted floats correctly and made sure all passages were clean. It started right up but had the same miss. I did a spark plug check and had erratic and intermittent spark on each plug. Check CDI amp box with Joe R's method and check out good. New coil. I put an inline tester from coil to distributor. Also at the same time put an inline tester on plugs while running. Steady spark going to distributor from coil but erratic spark at tester off of plug wire. Replaced stator, points, spark plug wires, added extra grounds to block to ensure proper grounding. Distributor cap is the original one but it looks fine; no cracks or signs of wear. Cleaned up contacts inside the cap and rotor. What could possibly cause this misfiring at idle? Also, it seems if I increase the RPM's while doing this test the plug tester seems to have more a steady spark but still misses occasionally. Please help would like to be out on the water for the 4th.
Tony
Tony