Originally Posted by
Skoontz
When setting points on any 1951-1976 OMC, you will get the best job by not using a feeler guage.
You are best using the factory timing fixtures and snugging them on the crank.
Then you use a timing light, i.e. a flash light that needs alligator clips and wire to make a connection. You clip one wire to the mag plate, then the other wire to the screw on the point where the condenser wires attach. Before you turn on the juice, disconnect the ground wire to the coil and leave it hang. You don't want to run any juice through the coils. If you cannot find this type of light, an electrical testing meter works too, I just like the light better.
Rotate the engine so the point set you are gapping are the point set for the correct cylinder. Place the pointer of the timing fixture between the cast in hash marks on the front of the mag plate. Screw the cam screw on the points back or fourth to get the light to flicker. Then once the light goes off, move the crank gently back and fourth over the hash marks and see where the light goes out. Ideally, you want no light as the timing fixture exits the hash marks.
Follow the same thing on the next set of points. Remove the fixture, screw back down the coil grounds and torque the flywheel back down.
I have two complete sets of these fixtures from OMC, and there is a guy who makes them on the AOMCI website for $35 each. Not only will they save time, they will be far more accurate than any feeler guages you use.