[Ralphy]

In my younger days I worked as a mech for a heavy equipment company. We had a crane that we used in the yard pretty much full time. Out of the blue they had it rented, the problem was it popped and backfired. After messing with wires , dist., etc... I finally pulled the #1 plug and stuck a screwdriver in the cylinder. The timing mark was off at least 10 degrees. So I guessed TDC and marked the harmonic balancer. Timed it to the mark, fixed! They never did replace it, just ran it that way.