Basic Buzz Coil question

[Zira]

I recently bought what appears to be a Ford Model T buzz coil. I got it to work okay, but there is a tiny spark at the points when it buzzes. Is this normal, or is it a sign that the internal condensor is bad?

Secondly, if I use this to run a throttle-governed engine (F-M Z 3hp in my case), how long should I set the spark to stay on - 10 degrees of rotation? 5? 15? I know my Fairmont rail car book says about 15 degrees, but it runs faster, and the guys on the RR car group have decided that it only makes one spark each time anyway (due to the time it takes the coil to charge up).

Thanks!

[Doug Deline]

I'm pretty sure this is normal, unless the points on the buzz reed erode too fast. It helps to reverse the polarity every few uses so metal is redeposited back and forth to the electrodes instead of constantly being taken from only one side.

[Andrew Mackey]

Slight spark at the points is OK. Adjust point tension to give best spark. 15 degrees is 15 degrees. The limitation is the amount of time the engine takes to make that amount of rotation. I believe the 3-Z turns at 475 RPM, or about 8 revolutions/sec. 15 degrees equals about 1/24th a revolution for spark. This means your spark duration is about .00529th of a second long! Hope one lights the charge!