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Generator light on and burning up regulators

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I have installed an HEI distributor and followed the install instructions, now I have a generator light on and I’m burning up my external regulator, I have no loose grounds. I have read on several forums several different opinions on what to do when installing one, so I’m looking for a solid answer on what to do. It’s a 1968 Pontiac Lemans with a factory 350 HO, manual transmission. 

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I have an HEI on my '63 Catalina but at the same time I put on a later 100 amp alternator because I also installed an A/C and the stock 35 amp would not carry everything. The new alternator has an internal regulator and has worked flawlessly. The questions I would ask are:

Where did you tie in your positive to the new distributor? Did it have points in the distributor, if so the coil was fed through a resistant circuit to keep the coil voltage under 9 volts. If you are tied in downstream of the resistor or resistant wire it could conceivably cause a problem. go back and tie into the ignition circuit at the ignition switch, make sure you are in the Ign wire and not the assessory circuit.

If you are already wired in that way then I can think  of three possibilities to solve the problem. One would be to install an alternator with the internal regulator, they are not that expensive on ebay. you connect all the factory wires and connect the external regulator wires together and toss the old regulator.

second would be to try a diode or a relay in the feed wire to the distributor to isolate the distributor from the ign circuit. I can not figure out any reason why it should cause problems with the regulator but since you apparently did not do any other changes it pretty much has to be something in the HEI causing the problem.

third the 70's and possibly 80's vintage Mopars used an external electronic regulator. they will work with a delco alternator. I used to use them on boats when the engine vibration would drive the point type regulator crazy. It has been so long since I have done that I can not tell you which of the two wires is the positive and which goes to the alternator but you can probably find that information on the internet somewhere.

good luck



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  • 10 months later...

The fix to this is adding a diode to L wire on your regulator to prevent the back feeding. The 10 DN alternator is so weak, even better is a 10 SI or even better a cs130.

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