The Stovebolt Site Forums The Shop Area Engine Shop alternator -vs- generator for electronic distributor

After I already purchased a 12 volt generator to upgrade my AD pickup I heard an alternator must be used with electronic distributors, but I hope someone with definate knowledge will get involved on this subject.

I'd like to get some discussion going on this subject I posted in the electrical bay. The reply to that post got me to thinking about voltage levels and I do not have both a generator and an alternator to test with a voltmeter.

I'm now SPECULATING that an alternator system consistently produces over 13 volts regardless of RPM. Meanwhile a generator MAY not even be able of producing 13 volts, and it may drop below 12 volts when at idle RPM.

Thanks

:confused:

A properly-adjusted generator system should provide plenty of voltage to support an elecrtonic ignition system. The CURRENT, not the voltage, of a generator might be a little low at idle, but that isn't going to be a factor unless there's a lot of add-on accessories in operation like a huge sound system, rear window defroster, or other high-current demands. The cutout relay, the part of the generator controls that disconnects the generator from the battery when the engine stops, should be set to close its points at approximately 12.5 volts. This is to be sure current flows from the generator to the battery, not the other way. Once the points close, the internal resistance of the battery determines how high the voltage must rise to recharge the battery. Against a well-charged battery, the voltage should rise to more than 14 volts. To prevent the battery from getting overcharged, a regulator limits generator output at about 14.7 volts.

A very low (discharged) battery will accept recharging current at 12.5 to 13 volts, at a very high rate of charge. Most generator systems also have a "current regulator" to limit the generator output to 25, or sometimes 35 amps of current to prevent overloading of the generator. As the battery recharges, the current flow will diminish, and the voltage will rise, controlled by the internal resistance of the battery. The battery, not the regulators, determines how much voltage, and current, the system produces. The regulators are only there to prevent overloading of the system, or overcharging of the battery.

There is NO reason an electronic ignition system won't work on a generator-equipped vehicle!

Let me suggest you read my Tech Tips article on DC charging systems.
Jerry

There have been reports of Pertronix modules dying due to voltage spikes caused by a generator. Proper bypassing of the generator should eliminate this problem.

I have no hands-on experience with the Pertronix system, but from what I've been able to read here on the forum, they seem to be too flimsy to be reliable. Since the GM HEI system is available, why would anyone waste time and money on a weak reed like a Pertronix ignition?

If spikes are a problem, just adding a big capacitor from the Armature terminal of the generator to ground should solve the situation. That's how we cured radio interference for years with the DC charging systems and AM radios fom many years.
Jerry

Jerry: When I go to the boneyard looking for a GM HEI, which vehicles should I consider for a distributor for my 62, 235? Afterwards, I'm going to need a primer on how to modify and wire the distributor.

Thanks!

Thanks for your replies. Hotrod's technical description makes very good sense to me. I have a big sack full of assorted caps to control the spikes so I can enjoy my high dollar original radio.

Patrick is the source who made me believe my new Mallory simply will not work with a generator. Who knows, maybe Patrick had a bad experience with an improperly calibrated regulator?

I've been detoured from drinkin' by Hotrod Lincoln! Thanks Buddies.

Tab, I don't think any of the HEI distributors are a direct swap into the 235 engine, as all the inline sixes were 230/250/292 by the time HEI was on the scene. I've heard there's a modification that allows them to be used on the early block, though. I prefer the distributor with the coil built into the cap, rather than the remote-coil model, but either one is just as effective at firing the plugs. Early to mid-80's 250 and 292 engines should be the ones to scavenge in the boneyard, I believe.
Jerry

Jerry: Thanks! Yes, I want one with the coil. I thought that I saw a post about modifying an HEI from a 250 to fit a 235. Anybody know how to do this swap?

here's an earlier post on the HEI modification.
http://www.stovebolt.com/bboard/cgi-bin//ultimatebb.cgi?ubb=get_topic;f=2;t=004636#000003

Fred: Thanks! This sounds like an excellent el cheapo mod. ;•D