Timing and voltage

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Chrisman889

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New distributor cap and rotor installed. Adjusted the timing a few degrees back and now the engine is running fantastic except now my voltage is down to12 when it's usually 14. It doesn't fluctuate at all when I Rev it up. Lights dim everywhere. Any suggestions on what it might be? Could retarding the timing mess with the voltage? Maybe something hooked up wrong with the distributor cap and rotor? I already checked for a loose ground or loose wires.
 
Yeah - if you're getting revs then the voltage should be good - sounds like a problem with the alternator / voltage regulator or as you said a bad connection - either ground or power. You can take it down to an Autozone type place and their equipment will test alternator, battery and starter.

Is the belt slipping on the alternator pulley?
 
Actually I meant was usually if I rev it, the volts will go up to about 15 or even 16 sometimes. It's just weird that all of the sudden when I changed a couple things the volt are way down now.
 
You really don't want the volts to vary that much - the electrical system is set up to run on a constant voltage - any little variation can affect the electricals of the whole vehicle.

If the engine is running well - solid constant RPMs then that tells you that the cap and rotor are set up correctly.

Once the engine is running well and spinning the belt consistently then that turns the alternator - that's where your system voltage comes from. If you have a bad battery and too much of the system is trying to run off of the alternator that could bring the voltage down.

If you've been using the battery a lot for cranking while you've been working on it and not driving it around after that to recharge the battery - maybe it just needs a good recharge either by driving or battery charger.

I would have the battery checked just to make sure there are no problems there.
 
either the gauge is wrong or you alternator is overcharging, typical healthy system should be 13.5 to 14.5 . The alternator may overcharge if the battery is weak or internal issues. The voltage may have dropped at idle if your changing of the timing caused the idle speed to drop.
 
It sounds to me like when you retarded the timing you dropped the RPM so the alternator can't charge like it should. If you had to retard it to run better, maybe your advance is stuck. I think that was mentioned in another one of your threads. Just a thought
 
Yes, VanGo, I think that may be exactly what it is. Thank you.
 
I've never heard of a timing adjustment having an effect on on the charging system and don't THINK that it could. I'm not an ASE mechanic, but it sounds to me like you've got a faulty alternator. I'd yank it and check the brushes in it first. If they look okay, take it and the battery and have them both load tested. One or the other is probably your culprit.
 
The theory is not timing per se, but idle RPM. If you retard timing you lose RPM and associated charging capability.
This is a common problem with underdrive pulleys for example. They in effect lower the revolutions of the pulleys which lowers the alternator output. On my own underdrive system on another car, I put an overdrive pulley on the alt so that my lights and fan would not drop so much at idle.
 
Bad alternator. Removed it completely, started it back up and ran the same exact way as it did with the alternator in it.
 
I would still get it bench tested. I'm still not sure it"s causing your problem
 
Put a new alternator in and voila! Runs beautiful. Thanks for all the info.
 
Did you keep the old one or use it for a core? If you kept it, take it apart and check the frigging brushes. I'm about 90% sure that was the problem. Of course, if it has an internal voltage regulator, that could also have been faulty. Bottom line it you have it fixed and that's ALL that really matters, right?
 
Now I'm just trying to dial in the new 650 Holley carb I put on. Just not sure about the two adjustment screws on the sides. I think one is for fuel and one is for air. It wants to bog down and pop if I step on the gas too much, rich mixture I believe. I guess this would be a topic for another thread though.
 
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