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drolston · 04-08-2020, 07:09 PM

I presume you are running Pertronix ignition, which has a good reputation on 12 volts and has been very reliable on my 12 volt flathead. But Pertronix has a less reliable record on the 6 volt version. Solid state electronics get flakey if they get too hot. So starting and running with the distributor directly in the fan breeze may keep the 6 volt unit running fine. But sit for a while with no cooling and the engine heat transfers to the distributor to the point that the ignition fails. Just a theory!

This theory can be tested. Run till the engine is hot. Shut down and immediately check the spark to see if it will jump half an inch with a blue spark. Then wait 15 minutes and check it again to see if the spark is weak, like yellow spark will barely jump a quarter inch. It that is the case, swap out the Pertronix to get a more reliable unit, or go back to points.

04-08-2020, 07:09 PM	#11
drolston Senior Member Join Date: Jun 2014 Location: Williamsburg, VA Posts: 1,627	Re: Hard to start. I presume you are running Pertronix ignition, which has a good reputation on 12 volts and has been very reliable on my 12 volt flathead. But Pertronix has a less reliable record on the 6 volt version. Solid state electronics get flakey if they get too hot. So starting and running with the distributor directly in the fan breeze may keep the 6 volt unit running fine. But sit for a while with no cooling and the engine heat transfers to the distributor to the point that the ignition fails. Just a theory! This theory can be tested. Run till the engine is hot. Shut down and immediately check the spark to see if it will jump half an inch with a blue spark. Then wait 15 minutes and check it again to see if the spark is weak, like yellow spark will barely jump a quarter inch. It that is the case, swap out the Pertronix to get a more reliable unit, or go back to points.