Distributor Box Matrix Lift Cam
This cam is fastened to the distributor back screw by means of a taper pin. There is no adjustment of the cam. It should not be detached unless badly worn, and then it should be replaced by a new one.
To apply a new cam: Drive out taper pin and slip cam off the shaft, placing a new one on the shaft in such a position that the holes in the cam will match with the hole in the shaft. Use an 8 x 32 headless screw to hold the cam in position. Put a thick matrix with a full size lug in the box in the regular way. See that the lift is adjusted to raise the matrix 1/32 of an inch above the upper rails. Then turn the distributor screws by hand, and when the matrix starts to raise and enter the screws, the side of the matrix opposite the distributor shifter should clear the threads on the distributor screws 1/32 of an inch. If the matrix does not clear the threads 1/32 of an inch, loosen the small screw in the cam, turn the cam so that when the matrix lift starts to raise the matrix it will clear the threads properly. Fasten the cam securely with the screw, and then run through a few lines to make sure that the cam is set right. Then drill a hole in the shaft and fasten with a pin.
Before applying a new matrix lift cam, make sure that the upper and lower rails in the box are not worn; if worn, renew the rails before applying the new cam. It is seldom necessary to replace a lift cam, due to the small amount of wear the cam undergoes.