Don: A timing light isn't used to set the timing on the "G." The "G" distributor has a mechanical spark advance and it starts to advance at low rpms and will affect you timing light reading. The proceedure for timing the "G" is the following: Remove #1 spark plug and put your finger over the plug hole. Turn the engine over with a crank or fan belt until you feel #1 starting up on the compression stroke. Now look through the timing inspection hole on the hood support and continue turning the engine until the mark on the crankshaft pulley is centered in the inspection hole. Remove the primary coil wire from the coil. Attach any kind of small test light between the ground and the coil wire leading from the coil to the distributor. Turn on the ignition switch. If the test light is lit, that indicates the points have already opened and the timing could be to far advanced. If the light is off it may be retarded. Under the distributor there is a clamp that has, I think, a 1/4" bolt through it that holds the dist. from rotating. Loosen the bolt slightly until you can rotate the dist. with your hand. Now slowly rotate the dist. You need to get the position of dist at the point where the test light is not lit. If the test light is lit rotate the dist. clockwise until the light goes out. If the test light is already out do the following, very slowly turn the dist with your hand counter clockwise until the test light just comes on. Tighten the dist clamp and it is timed correctly. The position where the test light goes form off to on is when the spark occures and fires #1 cylinder. I hope this is clear and helps.