VCCA Home Forums TECHNICAL - GENERAL Electrical - 6 volt Cut-Out Operation

This weekend I replaced the what appears to be the original Delco-Remy cutout (called a "Circuit Breaker in the shop manual) on my '37 Master coupe.

I replaced it after noticing that the current draw at idle would stay at about 10 amps, not the normal 2 or so for just the ignition. I did some testing and determined that it would not disconnect even if just battery voltage was applied to the coils. It would disconnect when there was no voltage.

Is this a normal failure mode? All I can determine is that the small leaf spring that resists the magnetic field in the coil has become weak over time.

The replacement is an aftermarket unit I bought through eBay a few years ago. It seems to work fine expect the engine speed needs to be at a very slow idle for the cutout to disconnect.

Any experiences to share?

Hello Rusty,

My cut-out switch appears to engage between 800 and 900 rpm and seems to disengage about the same or possible lower as I slow down for traffic or traffic light. I will try to give you a more accurate rpm range this week as I finally was able to find an armature for my generator and have it back on the road.

The disengage problem may be the points are starting to burn so they stick. ( Auto electrical is no where near my strong point, so this is my opinion )

The shop manual describes very well at to what generator out put the cut-out points open or close. It will be about in the 7 to 8 MPH range. The amp range figures int also. It is adjustable.

The points on the cut-out should close around 650 to 750 RPM generator speed. The points on the cut-out should open between minus 1 to minus 2 amps discharge. If the points in the cut-out are sticking the cut-out can be converted easily to a solid state unit.

The armature for your generator is very common and it is readily available.

Thanks to all for the additional inputs.

Based on the information in the '37 shop manual as I understand it the cut-out is not adjustable. You can adjust the output (amps) by moving the third brush. If the cutout (circuit breaker) is not working correctly the only fix is to replace it.

I have set the generator output to about 18 amps at the generator. On the ammeter it shows about 15-16 amps due to the load for the ignition. So that seems to be working as expected.

The cutout points are supposed to open when the generator voltage falls below battery voltage. They are supposed to close when the generator voltage builds up to 7 to 7.4 volts. In my case it would close properly after I started that car and the generator produced output. They would not open at idle and kept the field coils connected to the battery. That would draw about 7 amps from the battery.

I also did simple test by connecting the battery across the shunt winding in the cutout. Battery voltage alone would close the points. I am still trying to decide if that is a valid test.

The replacement cutout is working fine for now. I have an older G&D article abut the Peterson solid state cut-out but Google search does not deliver any information abut where to get one.

The cut-out is basically just an off-on switch so it is not adjustable for output. However the point gap, the air gap and the tension spring on the cut-out are adjustable.

A word of caution: 18 amps output on the generator is too high and that could tend to overheat the generator armature. You would be safer to adjust the third brush on the generator to around 10-14 amps max. output.

The 1937 has a higher out-put air cooled generator and the manual calls for 18 amp Max hot.

Thanks for the confirmation Gene. The shop manual actually states the output on the test stand could be as high as 20 amps. I backed off from that.

I agree that you can ruin an armature getting it too hot.

Yep, I know what the manual says but we have learned by experience that 18 amps output is still too high. As an example, the manual for the 1929-32 generator calls for 16-18 amps cold and 11-13 amps hot. That generator should be set at 8 to 10 amps hot.

You can get a Peterson regulator from:
James Peterson
Po Box 912
Bend Oregon
541-389-0438
jpetersonbend@yahoo.com

I have one on my 32 which has an unknown # generator and it works terrific.

Thanks for the contact info.