lights surging

[Virg464]

Looking for possible idea to track down for an issue (maybe it's normal). 66 Coronet, not really a street car, rough idle, built/building the entire wiring harness for the car. Starts and runs fine, running lights, hi-low beam, gauges, elec cooling fans, elec fuel pump. Everything works, but when it's running and I let it idle (approx 950-1000 rpm), the lights surge (intensity), the fuel pump rpm surges (pressure stays constant 7 psi). Running a 60 amp OEM alt, using an OE style electronic voltage regulator, MSD 6AL ignition. Off idle that all goes away.

I know this is a very general/non specific question, so any thoughts are appreciated.

 

[Aron Gleason]

I'd check all of your grounds.

 

[Geoff 2]

It could be the alt is on the threshold of charging, ie the alt output voltage needs to be higher than the bat voltage; alt voltage could be changing/varying slightly at this changeover point, which could explain why the problem goes away with more rpm which will increase alt output.
If this is the case, a slightly smaller alt pulley will likely fix the problem.

 

[toolmanmike]

Looking for possible idea to track down for an issue (maybe it's normal). 66 Coronet, not really a street car, rough idle, built/building the entire wiring harness for the car. Starts and runs fine, running lights, hi-low beam, gauges, elec cooling fans, elec fuel pump. Everything works, but when it's running and I let it idle (approx 950-1000 rpm), the lights surge (intensity), the fuel pump rpm surges (pressure stays constant 7 psi). Running a 60 amp OEM alt, using an OE style electronic voltage regulator, MSD 6AL ignition. Off idle that all goes away.

I know this is a very general/non specific question, so any thoughts are appreciated.

Put a voltmeter on it and make sure the how much the voltage is surging. It probably needs a regulator. The old point style regulator can be replaced with an electronic one that looks like the old one. Just make sure the case is grounded well to the firewall. A poorly grounded case will cause overcharging.

 

[493 Mike]

Put a voltmeter on it and make sure the how much the voltage is surging. It probably needs a regulator. The old point style regulator can be replaced with an electronic one that looks like the old one. Just make sure the case is grounded well to the firewall. A poorly grounded case will cause overcharging.

"using an OE style electronic voltage regulator"
In case you missed this.
Mike

 

[ckessel]

Get that on the wagon, at idle, with the LED's on. Going to get a relay pack/bypass setup from Crackedback in the near future.

 

[Sinitro]

It seems the alternator is having marginal output @ 950 RPM, given the accessories current draw the regulator is kicking in/out..
Suggested solutions are:
1. Revise alternator pulley size
2. Upgrade the alternator to a higher output one

Note a higher output alternator will supply more current @ a lower RPM than the present 60 amp one.

Just my $0.02...

 

[Virg464]

Put a voltmeter on it and make sure the how much the voltage is surging. It probably needs a regulator. The old point style regulator can be replaced with an electronic one that looks like the old one. Just make sure the case is grounded well to the firewall. A poorly grounded case will cause overcharging.

I will check the ground on the regulator for sure.

 

[Virg464]

Are the pulleys on the alt a pressed on item? Is there more to changing pulley sizes, maybe depends on brand of alt? Just curious encase I end up looking at the smaller pulley option.

 

[493 Mike]

Are the pulleys on the alt a pressed on item? Is there more to changing pulley sizes, maybe depends on brand of alt? Just curious encase I end up looking at the smaller pulley option.

Yes. There is a puller made just for the task.
Mike

 

[Sinitro]

Regarding alternator pulleys, Mancini has a nice selection.
Here is an overdrive pulley..

Powermaster V-Belt Alternator Pulley
Just my $0.02...

 

[RJRENTON]

Yes. There is a puller made just for the task.
Mike

On a std Mopar alternator, either round back or square back. The drive sheave is pressed on (no key) and requires a special puller to remove. LIKEWISE, the alternator must be dissembled to press on the new sheave. B4 pulling the existing sheave, measure the depth of the sheave is on the shaft AND NOTE THIS DIMENSION to install the new sheave to the same dimension so the belt centers will be the same. DO NOT HEAT THE SHEAVE TO SHRINK IT ON....FOLLOW THE FSM OUTLINED PROCEDURE TO REINSTALL THE SHEAVE TO THE DIMENSION MEASURED B4 REMOVAL. It's a simple procedure but the correct puller tool makes it easier. Don't know about alternator assemblies...aka Powermaster etc....
BOB RENTON

 

[Virg464]

Yes. There is a puller made just for the task.
Mike

I assume it's not the same as the tool for P/S pumps?

 

[493 Mike]

I assume it's not the same as the tool for P/S pumps?

I think it may be. As I age more things escape my mind.
Mike

 

[Carcinogen]

I found my wires had internal corrosion, coating looked ok, internally there was discoloration and green corrosion.

Ran new wires and connectors for alternator to regulator and lights/voltage steady now.

 

[Virg464]

I found my wires had internal corrosion, coating looked ok, internally there was discoloration and green corrosion.

Ran new wires and connectors for alternator to regulator and lights/voltage steady now.

This is all new wiring, had to build it, nothing came with the car. I think it may be the low amp alt that I installed, only 60 amps and the elec cooling fans take up half of that when they are on, not to mention the elec fuel pump...