Timing Question

[bob174]

I have an injected '73 2.0 that I am setting the timing on. I noticed last night that when I rev the engine from idle to 3500 rpm to set the timing per the manual, that the timing mark was not moving indicating that the centrifugal advance was not working. My question is how does the centrifugal advance work, and what might cause it to stop working?

[Dave at Pelican Parts]

There are weights inside the distributor that are attached to the distributor shaft by pivots. They are spring-loaded to return to center, but centrifugal force pulls them outward against the springs as the shaft spins faster. The weights are hooked up through a linkage to the "points plate", the plate that the points (or points-replacement gizmo) attach to. When the weights move out, the points plate rotates around the distributor a little bit. This changes when the points open and close, which changes when the spark is initiated.

The weights or the linkage attached to them could be gummed up with old grease, could be rusted, or something else could be going on. You can try taking the dizzy out and spraying it with your favorite penetrating oil, but you may wind up having to disassemble and rebuild it.

--DD