Good point, Joe. I was about to mention the positive stop method of finding TDC. That's how we do it on the race engines, as the harmonic balancer can be off a little due to production tolerances. I use a spark plug shell with the porcelain knocked out of it, and drill and tap the shell for a 3/8"-16 bolt. screw a long bolt into the plug shell until it contacts the top of the piston a few degrees of rotation from the top, make a mark on the balancer with a felt tip marker beside the TDC mark on the timing cover, then turn the engine backwards until the piston touches the stop again. Mark that point. Measure halfway between the two points and make a permanent mark there. When the new mark lines up with the timing pointer the piston is at TDC.
Jerry
