Diode for Atomic-4 engine run-on?

[hcpookie]

I put a Delco alternator on my A4 due to issues with the original Motorola. Ax expected, it continues to run after I kill the ignition due to existing current. The solution, according to all of the hot rod and tractor conversion websites, is to put a diode on the line. It certainly beats physically pulling the wire

Question for those who have done this - how big a diode should I ask for at Radio Shack? I've read 1 amp is "OK"... just looking for opinions. I am physically pulling the wire and I'd like to clean it up.

 

[Howard Keiper]

It's interesting you should ask...I, too, have a A-4 run-on problem. I discovered however, that my alternator is charging at 16+volts (that's one of the things having a voltmeter on your panel can tell you) at crusing speed. The only way I can kill it with the switch is to throttle way back to idle for a few seconds, then turn off the switch. That 16 volts alone tells me the regulator has gone south.
Howard Keiper
Sea Quest
Berkeley

 

[SAILSHIGH]

Interesting

Guys,

I rewired my panel with a kill switch. I have a 1 wire a/c delco alt. and wired the engine like a old car. A wire to the coil on a kill switch.

I have never heard of this problem of it keeps running. My alt also runs at 16 volts.

Very Interesting.

Good Luck,


PS

HCP.
Grand lake of the cherokees is located in North east oklahoma. About an hour up 44 toward Joplin. I worked in Virginia Beach for years. I miss that part of the world.
Cheers,

 

[hcpookie]

From what I've read (on the hot rod engine forums) is that the run-on is due to the charge on from the coil energizing the alternator, then when the alternator produces charge, it fires again, and the whole cycle repeats.

The GM factory "fix" is to put resistance in that line - in the form of the ALT light - that resistance burns the current and keeps the alternator from getting "excited" again. Or use a resistor wire. That is wire that produces X amount of resistance per foot - usually a cut to order configuration.

The crude way is to pull the wire. That's what I'm doing now, but I have to pull the engine cover every time.

I'm keen on the KISS method, and it would complicate the circuit, and provide more things to break, by putting another piece into the line. Thus, the best way I can think is to put the exciter wire not on the kill switch, but on a relay near the engine, even a powered sender unit or something like that. The diode method is my 2nd choice.

I need to sit down and figure out the best place to put the wire, but for now I'm just going to rig a diode.


Wes where is Grand Lake? I grew up in OKC and that seems to ring a bell.