Al Gietzen wrote:
>>  Al
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I have been doing this since 1980, and that last one lost me.

 

Any method used must involve both the leading and trailing plug holes. Any method that uses sightings of apex seals in those plug holes will be off between 4 and 9 degrees (advanced) because the plug holes are both located higher in the housing than neutral. Also the distance between plugs is different in various housing years.

 

This is good for an approximation of TDC only. Good for first start and dropping in the distributor or crank angle sensor. The pulley should be marked with an accurate TDC and at least the maximum total advance, or lacking that, the TDC mark and an adjustable timing light. Has the knob on the back. Costs a lot more. You rev the engine up to test RPM, say 6,000 and turn the knob until the TDC mark is under the pointer. Look at the pointer on the back of the timing light it is pointing at your total advance at 6,000 RPM.

 

Use any minimum volume system to find an accurate TDC.

 

20 to 24 degrees is plenty of advance unless have to use high octane fuel all of the time, then 26 to 27 degrees is fine.

 

Mark the starter ring teeth with different color paint dots for TDC and maximum advance. Buy an inductive (Clip on) timing light and practice using it.

 

It was 80 today in Zephyrhills. I flew my Super Cub and BF-109 before the wind picked up around 10:00.

Not a single cloud to be seen. The sky divers were up all day.

 

Lynn E. Hanover