Having problems with getting sufficient voltage to keep car running with the headlights on. Appears the 6AL box does not want to run is if it does not get sufficient volts. Get almost 14 without anything on. But goes to under to about 12.5 with headlights or heater on. With the headlights on, the car will stall when going back to idle or start missing after crusing for a while. I have

1) Changed from 60amp to 100amp alternator, 1 wire.
2) Replaced underdrive pulley's with stock pulley's.
3) Replaced ground and starter wire.

Each would help a little but none solved the problem. Or is everything working as it should.

thanks,

Scott

 

Sounds like a wiring problem. The hot wire going to voltage regulator in the alternator is the same hot wire that provides power for the lights so if your 6AL box is on the same circuit that could be a problem.

 

Is the belt tight? Check volts at alt post and bat post under load and report back Also check volts at alt case and bat neg. Connect volt meter grnd at bat neg and voltmeter pos at bat pos. Is it 12.5 as you stated? Now connect voltmeter pos to alt bat post. What is it there? Connect voltmeter pos at bat pos and voltmeter neg at alt case. What is reading there?

100 amp should be plenty to keep volts up, but you may need to go to a 3 wire setup.

 

I'm leaning towards the 38 year old wiring myself. I just replaced the harnesses under the hood of my 70 4 months ago and wow did that make a difference.

 

Scott, did you ever get your alternator wired correctly? When I last looked at your car, the alternator was not wired correctly and would not have charged properly.

 

It is a one wire and have a single 8 guage wire going from the battery to the alternator. I think I made the change after you saw the car. The alternator does charge but not under a load.

Plan to try Stellar's recommendation tonight and report back. Having been thinking of following svnt442's advice also. Anyway to test a wire to see if it is bad?

 

The volteter in the car is not very accurate. Measured 14.15 at the battery no load and 13.85 with the lights on. About .25 volts higher at the alternator. So I need to rethink the probelm as to why with the headlights on the motor will stall when going back to idle, will stall if idle for a long time and start to sputter if cruise for to long. Turn off the headlights and the problem goes away? Anyone heard of the 5al box causing a problem like this?

 

Use your multi-meter and test the voltage at your volt meter in the car and compare the two. You still may have a voltage drop large enough to cause this. Again I point to the 38 year old wiring.
I need to take some pictures of what I found when I replaced mine. It was BAD. I still have them in a box in the garage.

 

Update and additional question - I have replaced the front light harness and found a bad ground. Again this helped a little. Still when you turn the headlights or heater on or but down the top the motor will stall or hesitate. Definately an electrical issue. My next suggestion was to get a 1000amp battery as the present batter is not big enough to handle the sudden current draw caused when the lights, heater, or top is turned on. Any chance this is correct?

 

Finally solved the problem. The motor needed a ground strap from the motor to the frame. Motor would run with the top going down, or the heater and head lights on. Things looked good, the car was going to run well for the summer. Until I was come around a turn, hit the gas and boom, a lot of clanking and oil all over the ground. Oh well may next summer

 

Damn...threw a rod.

 

Ouch

Sorry man.

Chatter Chatter second Gear,
What's that funny noise I hear,
When I shifted at ten thousand,
Something flew out thu the housing.