There's a quick way to find true TDC, and it's pretty simple to do. Take an old spark plug and machine or grind the area where the porcelain meets the steel until the porcelain can be knocked out, leaving just the empty steel shell. Drill & tap this piece with a 3/8"X16 thread and install a piece of all-thread rod about 3 inches long. Add a lock nut if desired. Screw this device into the #1 spark plug hole, and adjust the all-thread until it sticks into the cylinder a short distance. Turn the engine by hand (spark plugs out is easiest) until the piston stops against the rod. Mark a spot on the flywheel or the crank pulley adjacent to a bolt head or some other reference point with a center punch, felt-tip marker, or grease pencil. Turn the engine backwards until it stops again. Mark that spot. TDC will be exactly halfway between the two marks.
I've done this procedure on every race engine I've built for the past 30+ years, and it's amazing how far off some factory TDC marks are!
Jerry
Last edited by Hotrod Lincoln; 09/17/2008 10:01 PM.
