Loading motor for timing adjustments

Pappy said:

Sinkingfast said:

Here is one reason maybe..

My '76 15hp has an upper needle bearing and needs running clearance. And has points. When static checking the timing the magnet in the wheel forces the crank towards the head. When running the load changes 180 degrees on the crank. The points are not exactly 90 degrees from this movement. I have found the timing when not running is different then when running. Had to set the points differently from each other for the timing to be correct when running.

Got a couple of atom point eliminators and all is good now.

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On the 1974-1976 9.9-15hp engines the outer plastic ring that locates the mag plate assembly is probably the culprit on the points gap/timing issue. You are sort of on the right track though. The magnets in the flywheel, when running, pull against the coil laminates and will change the gap in the points when the mag plate is loose. There was a bulletin to change out the original plastic ring for a newer Delrin ring. Stabilizes the plate nicely.

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Yea, I've got the brown ring and I dimpled the pivot boss on the motor to tighten that area up. Thing is the upper crank race area measures no wear and I have tried 2 used and one new needle bearing and all have the exact same clearance at .0045in. So I looked up clearances for needle bearings and that falls where it should.

I did install a spring on the mag plate to hold things from rattling around. That helped more than anything except for the Atoms. I was thinking about adding the charge coil to maybe balance out things but...haven't yet.

I guess timing error running or not, loaded or not is probably motor dependent.

Use a test prop.