Why

Right after the switch to 12 volt batteries, in the era of coils and points there were 2 basic ignition systems. For simplicity I will call them the GM and the Chrysler. (Ford was in there somewhere!!)

I drove a road service truck in Pittsburgh and EVERY time it got to be high humidity (rain, morning dew etc…), the Chryslers’ would not start.

What was different?
The Chryslers were wired like the garden tractor. Battery voltage was connected to the coil by the ignition switch, then the starter was engaged. Hopefully the engine would start.

If the Chrysler would not start, it was time to soak every part of the ignition with ignition spray and cross my fingers!!

But, GMs’ never (almost) had this problem.

What was different about the GM?

The GM used a dropping resistor so that when the ignition switch energized the coil, it was with a lower (6?)volts. During running the ignition would operate on the lower voltage. Since the coil was designed different for GM, both Chrysler and GM had the same secondary operating voltage to the spark plugs.

Now GM’s trick. They ran a second wire from the connection that energized the starter, bypassing the dropping resistor, directly to the ignition coil.

GM was now able to deliver a higher voltage to the coil during cold starting, which is when the garden tractor also needs it the most.

Those of us “my age” remember GM cars that would only run when the key switch was held in the “start” position. That was because the voltage to the ignition was higher.

This might be a simple solution for those garden tractor (and some gas farm tractor) owners that have that machine with the chronic hard to start issue.

Wouldn’t it be nice to have higher than operating voltage going to the coil during cold start, rather than lower than operating voltage we have now that is caused by the high current draw of the starter during starting.

Any Volunteers??

Sorry, solid state ignition owners need not apply!!