69 435 coil problem

[Thomas C.]

Having a problem with my 69 435. I noticed the battery guage fluctuating widly and well into the plus ranges, at that time the car would not idle and only run at higher rpm. Opened the hood and saw smoke coming from the neg terminal if the coil. I assume I need the alternator/voltage regulator rebuilt? Should the coil be replaced? would that cause the stalling out at idle? Thanks, Tom

[Rich G.]

Re: 69 435 coil problem

Tom

I had a bad coil wire on my 68 L71 (high voltage wire) and I had similar symptoms. It would run good at over 1200 rpm but would quit if it got under that and would be tough to restart when hot.

Sorry to hear about the regulator problem.

Rich Giannotti

[Joe L.]

Re: 69 435 coil problem

Tom-----

I don't know if there's any alternator or voltage regulator problem here, at all. However, if there wasn't such a problem to begin with, there may be such a problem now. In any event, 1969 Corvettes were the first year to use an alternator with an internal voltage regulator. This regulator is completely solid state and is non-rebuildable. They can be easily tested, though, and, if defective, can be easily replaced (with the alternator dis-assembled, of course). The alternators are pretty easy to rebuild, too. Usually, brushes and bearings are all that needs to be replaced. Diodes, rectifier bridge, stator and rotor can be rather easily checked for serviceability and, usually, are fine for continued use.

One word of caution, though: 1969 Corvette alternators are among the most valuable of all Corvette alternators. Of course, it's the case halves and "numbers" that represent the "valuable components"; the internals are easily and cheaply replaced. The 1969 drive end case half is quite fragile and weak. This case half design was used ONLY for 1969 and most, if not all, of 1970. Only Corvettes and a few other models used these case halves so they are quite rare. Plus, the "numbers" were unique to Corvettes. The drive end case half is also the case half with those "fabulous", "mouth-watering" "numbers". So, it's "doubly" valuable. You want to treat it with the UTMOST care when you're rebuilding it.

[Duke W.]

Re: 69 435 coil problem

You need to attach a voltmeter and look for a steady reading between 13.5 and 14.5 volts. If it jumps around it's likely that the regulator is bad, but inspect the side connector and make sure the contact is good.

If your early integral regulator alternator is like the later units, if one of the side connector circuits goes open it will overchange, and if the other one opens up it will not charge.

The second order vertical shaking force on my Cosworth Vega has caused many regulator/side connector problems over the years. It's been through regulators and broken the female terminals on the side connector harness. The last problem was a worn regulator spade that caused an intermittent connection of the red wire that resulted in intermittent overchange. It wasn't until I removed the old regulator that I noticed the spade was worn widthwise and it measured at about .030" wear. The new regulator with tweeked terminals to achieve a TIGHT connection has been okay ever since.

V-8 engines don't beat this connector apart like on a 7000-rev inline four, but IMO connectors should always be checked in any circuit that has a problem, especially on a 35 plus year old car.

Duke