[Michael C Henry]

Piston stop bolt a tool offered by Moroso, Comp Cams, and the like. The stop bolts come in spark plug thread sizes. Mine #4792 is from Comp Cams and has a solid brass body 18mm x 1.5 and an adjustable brass bolt , my FE has those threads. The body screws in place of the spark plug and the adjustable brass bolt that will contact the piston. Remove all the plugs for ease of rotating crank by hand. Screw the stop bolttools body into the desired spark plug hole (#1) rotate crank gently in one direction, all the time feelling for resistance when piston touches the stop bolt. Mark or record that point, then rotate crank in other direction, again by hand feeling for that contact. When that stops markor record that point on the timing -balancer marker. Actual top dead center is exactually in the middle between those two marked points. If you have the stop bolt adjusted high or short the gap between the two marked (or recorded )will be smaller. But too high and the piston will not make contact with the stop bolt. They make degree wheels that can be attached to the harmonic balancer to make this as acurate and easy as posible. This process is often used when degreeing in a cam shaft. I used it when figuring out where my actual TDC was with my older original harmonic balancer (they can slip) making the original timing marks not acurate. I bought one stop bolt . I Know I put it some place really special, I haven't found it so I had to buy a second stop bolt.