Timing and Knocking (getting worse)

Chuck Sea/Tac said:
A sloppy distributor shaft, will/can cause ruff running, because the point gap is changing. However I don't see how it would cause retard/advance problems, or knocking.
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Play in the top bushing can allow the weight of the rotor (it's not balanced) to push to the heavy side, and at 1000 RPM this could open the points wider than the normal gap on a couple lobes, but less than the normal gap on the light side of the rotor. The side that opens wider will have advanced timing, and the other side will have retarded timing.

To demonstrate how the unbalanced rotor can cause this I turned an old distributor shaft to 3/8" on the bottom end, so I could chuck it in my 1000 RPM drill. I then installed a cam and rotor and turned the drill on. The unbalanced rotor will shake the drill no matter how tight I hold it. This is why I balance my distributor rotors.:) It's the same principle for adding counterweights to the crankshaft.
 
Here's a picture of my balanced rotor. I used my Dremel to cut away excess plastic, then drilled two holes for screws and nuts.
 

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  • Timing Rotor Location.jpg
    Timing Rotor Location.jpg
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Hey Jim, when you say that the timing is effected, is the point gap closing and the engine running rough and stopping. Then you retime the engine and it runs fine for a while and starts running retarded again?
 
As Urus mentioned:


The stock distributor has two washers under the screw:

1. A lock washer

2. A THIN flat washer.

If either washer is missing, the cam screw will bottom out in the distributor shaft and appear tight but the cam will move around.

I have seen some Repro parts where the flat washer is not used. They use a thicker lock washer instead.

Some "Rick Packs" from the 60's had screws that were too long and bottomed out even when the correct lock washer and flat washer were used.
 
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