[mr0077]

Zimmy, use Ron427's method to make a piston stop, but do two things...1) tap the inside of the sparkplug shell (I think I used a 3/8" tap), and 2) make the end of the bolt going toward the piston ROUND and SMOOTH. Now you have an adjustable piston stop. As you turn the engine over, you can screw the bolt in or out as needed for the engine, so the piston will contact the stop (end of the bolt) maybe 15-20 degrees from top dead center. Contact the stop going both ways, mark each location. The middle of the marks is TDC.