HEI distributor problems

[SunSoaked]

Ohhhh...... the plot thickens. Sub'd. I too would lose the 1 wire alternator except I made that mistake in the past. Pass the popcorn please.

[Killer Bee]

Originally Posted by RodnRudy

HO455 you lost me when you spoke of AC voltage. How do you check AC voltage with the VOM?

here's a basic explanation with a couple of illustrations that should clear a few things up

A Short Course on Charging Systems

[RodnRudy]

Originally Posted by HO455

So there has been no changes to the charging system during all these failures?
If so have you checked the alternator output for AC voltage? If the diode bank in the alternator is failing AC voltage could be spiking the modules and causing the failures.
This one of those times an oscilloscope is handy.

No no changes to the charging system other than I put a new battery in Sat.
I checked the AC voltage at the positive post of the alt. with engine idling. VOM set on AC voltage. It read 31.6 volts.

[RodnRudy]

[QUOTE=RichardJ;8746681]>>Super Lube silicone heat sink compound. Bo


>> I noticed when I tested voltage while running was the voltage would drop to 4 or 2V just for a millisecond and the be right back to 13.8. I checked the running voltage at both the distributor plug and at the fuse panel bulk head connector at the firewall.<<

Do you get that 4V at the Alt Bat terminal?

The 13.8 is at idle? What is the Alt bat terminal voltage at idle and with the engine held at 15-2k rpm for a full minute?

The 2 or 4 volt reading I was getting was at the distributor lead . I wasn't getting a good enough reading with my VOM. With a better connection the reading is 13.8V eng. idling.
Alt bat terminal voltage is 14.6V at idle and at 15-2k rpm
That Super Lube is what I have and I'll get a good CPU at Best Buy but I've had three modules fail using the compound that came with them.
I've used one wire Powermaster alts. on my last three street rods with no problems.

[RodnRudy]

So I pulled the AC/Delco HEI and installed the new DUI distributor Sat. I set the timing at 14* and it's 34* all in at 2500rpm. Put in new plugs gaped at .050 per DUI's recommendations. The truck runs better and is more responsive. I checked the old distributor and could only find a frayed ground wire at the module connection. I guess time will tell if I've solved the problem. I carry a spare module with me. Thanks to all who gave me insight, advice, ideas, and opinions.

[Southcity]

We appreciate you keeping us updated with your progress, it's helpful for all of us that use this board. Hope your new setup is problem free for a long time to come!

[gmc684x4]

I am concerned over the ac voltage reading it should be zero volts

The altenator has rectifer bank to convert ac power created by the altenator to dc for usage in the truck

I am going to try this with my truck when i get it back together

31.6 ac volts the hei modual is built for 12 vdc the ripple voltage may be hard on it causing it early failure

Do you still have your other rides with the one wire alt to do the ac volt check on them to compare?

[RodnRudy]

Thanks for the feed back on the AC voltage. I'm going to call Powermaster and hopefully talk to a tech who can give me some insight on the AC output. I'll follow up after I find something out.

['68OrangeSunshine]

Originally Posted by RodnRudy

HO455 you lost me when you spoke of AC voltage. How do you check AC voltage with the VOM?

On some meters, you switch it from DC to AC. On earlier or simpler meters, you have to change out the red lead and plug it into the AC hole.

[HO455]

Sorry I lost track of this thread. Physically you check the voltage in the same places you did before. And as 68OrangeSunshine said you have to configure your voltmeter to read AC volts instead of DC volts. If you need more information post a photo of your meter and we can point you in the right direction.
The link that Killer Bee posted is good information about how the alternator works. Ideally the diode block will prevent you from seeing any AC voltage. The fact you are seeing 31 volts leads me to believe it is failing.
Do you have any humming on your radio?
Here is a link that has some more information on the subject Although it is slanted towards new cars the principles are valid.

https://www.autosuccessonline.com/al...n-the-machine/

[RodnRudy]

Originally Posted by gmc684x4

I am concerned over the ac voltage reading it should be zero volts

The altenator has rectifer bank to convert ac power created by the altenator to dc for usage in the truck

I am going to try this with my truck when i get it back together

31.6 ac volts the hei modual is built for 12 vdc the ripple voltage may be hard on it causing it early failure

Do you still have your other rides with the one wire alt to do the ac volt check on them to compare?

No I don't have the other rides. I build one, enjoy it for a couple years, sell it and build another. Can't really afford two at a time.
Anyway, I talked to tech at powermaster and told him of my problem. He told me the ACv reading was a false reading but said to send the alternator back and they would go through it and check all functions and let me know what they find out. I sent it yesterday and hopefully I'll get some feed back in a few days. I'll let you know what I find out.

[dmjlambert]

See if they will send you the bad internal parts back with the alternator, if they find and fix anything. It will be educational.

[VetteVet]

Originally Posted by dmjlambert

See if they will send you the bad internal parts back with the alternator, if they find and fix anything. It will be educational.

Yes I agree.

[RodnRudy]

Ok so I hope this is the final chapter of my HEI module problems. I got my alternator back from Powermaster Fri. and also a follow up call from the tech explaining what they found. There were no internal problems with the alt. They did find paint residue on the mounting lug and on the top adjusting lug. Also they said the belt was slipping on the pulley as you can tell from the pic I've added. They installed a new pulley, cleaned the mounting surfaces, and ran another dyno test, results also in the pic. The tech told me to tighten the belt really tight as the newer higher amp alts. put out more load than the originals and are prone to slipping. And he said to run a dedicated ground wire, 6ga, from the threaded lug on the rear of the alt. to a good engine ground. The tech told me that bad grounds can cause voltage spikes which the modules don't like and can cause premature failure. I reinstalled the alt., made a 6ga ground wire running from the alt. to the intake, and cranked the belt tension down so there is no flex in it. The alt. output is now a steady 14.7V at idle and also shows a steady 14.2V at the HEI pos lead. Thanks to all who offered advice and opinions . I'll drive the wheels off her and hope all is good. Only time will tell.

[gmc684x4]

Nice to learn they have really good service
Great to hear you have it fixed

['68OrangeSunshine]

Thanks. I've been thinking of switching my '68 C/10 to a 3-wire 100A, Powermaster alternator. Good to know their customer service is OK.

[HO455]

Congratulations! And thanks for the follow up post with your solution.