Reply To: Starter motor for a 1956 Johnson RJE-18

[David Stanton]

outboardnut wrote:

I always wondered if a shop can turn a 6 volt starter into a 12 volt.

Those 6 volt starters work fine on 12 volts. Just change the choke solenoid and the starter solenoid to 12 volt units. The choke solenoid could just have a suitable resistor placed in series with it with resistance same as the solenoid to soak up half the voltage – but watch the power rating of the resistor – you want to have a power rating that’s above P=V-squared over R or P = 36/R. Due to the inductive reactance of the motor spinning faster with 12 volts, the current draw is not twice the current draw at 6 volts as Ohms law would suggest – it increases some, but doesn’t double. Leaving the 6 volt starter when converting an old car to 12 volts is common practice also. I have done this on two early 1950s cars and a 1956 30HP Johnson with no problem.
Dave