Points burning

2

25 TA

Junior Member
I am having a lot of backfiring on my 1928 overhauled motor. New motor has 150 miles or so, and has been backfiring. Timing is dead on, points and condenser are new. I changed thr distributor prior to rebuild and had no problems. The only thing I have found is that I set new points etc, and I am pulling 7 1/2 volts, when it starts backfiring , I am pulling 10 or so volts, and points are burned. I opened up the generator, and armetor looks like it has been hot and looks like it might be missing some cellophane etc. Could this be the reason for my backfiring. If so, any comments on installing a GM type alternator one sire. Sorry for being so long winded, I just start and I go

Thanks for any feed back

25 TA
 
Exactly the same problem I had.

Powerhouse genny was overcharging.

It was pushing 18 volts on a 12 volt battery.

Burned the points in minutes.
 
25 TA Are you using "modern" points and condenser? There's been a batch of poor quality "modern" condensers on the market.
 
You should get your charging issue in order first or install a resistor on the hot side of the coil to limit running voltage.

Back before points went away (they don't even have them on my B&S snow blower) if you have a car that showed good point contact wear, no peaks or valleys, we would leave the condenser in place because it has the most to do with this.

Maybe scrounge around for an old condensor to go with your new points and a resistor on the coil to limit running voltage.

Ford used to run a hot wire from the started solenoid to the hot side of the coil to get battery voltage during cranking and then limit the running voltage thru the resistor when running for a longer point life.

Cliff Ramsdell
 
What electrical system are you using?? 6v or 12v ?? You only mentioned voltage at/to the points..
If 12v,, you may have the wrong coil or no ballast resister.. 10v is a bit much for the points..
If 6v,, then it appears you have an electrical connection, open or ground issue somewhere.. The 7.2v sounds fine but it shouldn't rise above that.. A generator should work just fine once your problem is corrected..
 
The weaker (or smaller) the battery is, the less it can control the output of the generator, and that's one reason a few of us make electronic voltage regulators for the original unregulated generator used on the Model A. My 29 had a weak 6 volt battery and the powerhouse generator, even on the lowest setting, was still pumping in 14 amps at 10 volts. That's what got me started making EVR's. Since I installed the EVR and bought a junk yard battery about 8 years ago, everything has been fine and I haven't had to add any water to the battery in all these years. That reminds me, I should check the water level in the battery again. It was full the last time I checked 4 years ago.

My 29 did a lot of backfiring, but it was a poor repro ignition switch where the contacts wouldn't stay in contact. I removed the back of the switch and fixed it.
 
Many do not understand that in the Model A electrical system there is only a reverse current relay, not a voltage regulator . The battery is the voltage regulator. If the battery ground deteroriates the voltage is no longer regulated and the ignition system quickly turns to toast. The ground connection at the battery and at the frame must be checked on at least an annual basis. A second ground from the frame to the engine is cheap insurance. I personally use and recommend Tom's EVRs. Gar Williams
 
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