47-55.1 Grrr... broke down again!

[Livemeyer]

So my 1951, Mabel, got me about a mile from home today and decided to stop running. The 327 v-8 has been a thorny motor ever since I installed it (I don’t think the CL seller was up front about its issues). Last year I got it on the road and one of my first drives in the truck it died because the coil in the HEI distributor fried. This time, it behave the same way, so I suspect its the same thing. Now, I rewired this truck and 12v goes direct to the distributor. One thing I’m curious about is I have seen firewall mounted ceramic resistors, and I’m curious if I’m supposed to have something like that in line. I’m just thinking out loud here, I am getting AAA to bring her home and then I’ll have my tools and can start troubleshooting.
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[Livemeyer]

Originally Posted by Livemeyer

So my 1951, Mabel, got me about a mile from home today and decided to stop running. The 327 v-8 has been a thorny motor ever since I installed it (I don’t think the CL seller was up front about its issues). Last year I got it on the road and one of my first drives in the truck it died because the coil in the HEI distributor fried. This time, it behave the same way, so I suspect its the same thing. Now, I rewired this truck and 12v goes direct to the distributor. One thing I’m curious about is I have seen firewall mounted ceramic resistors, and I’m curious if I’m supposed to have something like that in line. I’m just thinking out loud here, I am getting AAA to bring her home and then I’ll have my tools and can start troubleshooting.
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I had been working on the truck this past week and I found I had forgot to put the spark plug wire back on #1, I had removed the valve covers and pulled the wire so I could get the valve cover off. I wonder if that might have shorted something?
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[Wrenchbender Ret]

If you have factory HEI you should not have a resister in the circuit. Usually the failure problem is in the module. Often it is the pickup coil. I would replace both of those as getting stranded is not good. Sometimes its hard to diagnose the cause because they are intermittent. You get to checking things & suddenly its working again.

George

[Livemeyer]

Originally Posted by Wrenchbender Ret

If you have factory HEI you should not have a resister in the circuit. Usually the failure problem is in the module. Often it is the pickup coil. I would replace both of those as getting stranded is not good. Sometimes its hard to diagnose the cause because they are intermittent. You get to checking things & suddenly its working again.

George

OK, back home now, confirmed it has no spark It must be that module again. Unlike the first time, this time it has a new distributor with a new module. There's an auto electric shop down the road, maybe after I get it fixed I'll run it by them and ask them to evaluate it. I can't keep having this strand me.

Another thought: I see lots of Chevs with an aftermarket Accel or MSD coil. I don't see the purpose on a HEI system. Maybe someone can explain why one would invest in such, and if it would help in this situation or just be a waste of time.

[Dan in Pasadena]

Originally Posted by Wrenchbender Ret

If you have factory HEI you should not have a resister in the circuit.
George

"Factory" HEI in a 327? Uhhhh, no.

[Black93GT]

Originally Posted by Dan in Pasadena

"Factory" HEI in a 327? Uhhhh, no.

I had a GM HEI on mine too and fought a hard start issue for a few months. Especially hard to start once the motor got warm. Low voltage, bad grounds were the first issues I needed to overcome before finally finding an intermittent weak spark. At that point I didn’t have the patience and just bought a new one.

As previously stated.... no resistor on an HEI. Provide a full 12v.

[mr48chev]

Originally Posted by Dan in Pasadena

"Factory" HEI in a 327? Uhhhh, no.

True there in that Chevrolet didn't have HEI until 1975 and the last 327 (big journal ) were 2 barrel versons built in 1969.

Factory HEI would be one made by Delco that came in a 75 or later GM vehicle though. Or came across the GM parts counter.

Also true is that HEI likes full voltage to work right. If you have a weak charging system the voltage might not be there for it to work right.

[Wrenchbender Ret]

Originally Posted by Dan in Pasadena

"Factory" HEI in a 327? Uhhhh, no.

I realize HEI didn't come from the factory in 327's but many have been installed in them.
George

[dsraven]

probably what was meant was a "factory" HEI from a newer year. still a factory unit instead of an aftermarket HEI. installed in an older engine instead of those old style points units.

[65blackfleetside]

Make sure that you have 3 good grounds- I fried my new HEI in the last 350/ C10 that I had. You need: Frame to motor. Frame to cab. Rear bed to frame.

[Livemeyer]

Originally Posted by 65blackfleetside

Make sure that you have 3 good grounds- I fried my new HEI in the last 350/ C10 that I had. You need: Frame to motor. Frame to cab. Rear bed to frame.

Interesting you say that. I had my truck in the shop in 2017 to install all new brake lines, and while under the truck the shop guys said I needed a good ground. They ran one from one of the transmission mounts. I did one myself from the motor to the frame. I had truck in the shop in June for aluminum head upgrade and when I got it back I found the shop had added a second engine to frame ground. You'd think I have this covered.

Now, you bringing the ground issue up, why do you think this might be a problem? Do you think a grounding issue would cause the HEI ignition module to fail?

Truck is difficult to turn over and start when warm, and I'm unsure why, but this is a separate issue from the HEI module going out. At least I think so. When I got the truck back from the shop that did put the new heads on the truck was running funny, stuttered and backfired through the carb. I was at another shop for something else, they put a timing gun on it found it was 0 to 3 degrees advance, when it should be 8-12 degrees advance. Moving the advance up made it run better, but damn if it don't like to crank when warm! I also went out last year and bought a top of the line $200 gel battery. Like I said, so weird voodoo with this engine...

[mr48chev]

From what I have seen modules usually fail due to another issue. Bad coil too much resistance in a circuit or ??

The leads on the pickup coil often fail right next to the unit where the continual flexing of the wire due to the advance plate moving causes them to break the same a breaking a wire in you hands by bending it in and out to the spot at the bend fails.

This link is to my photobucket page and the particular album is a NAPA Echlin HEI service bulletin from the early 80s that pretty well walks you checking an Hei component by component. It won't test a module but you need a module tester that some parts houses have for that. There are several pages and I'd suggest saving them to your computer where they may be easier to read. I've use it times over as have friends who I have given copies to. https://s173.photobucket.com/user/mr...library?page=1

[Livemeyer]

Originally Posted by mr48chev

From what I have seen modules usually fail due to another issue. Bad coil too much resistance in a circuit or ??

The leads on the pickup coil often fail right next to the unit where the continual flexing of the wire due to the advance plate moving causes them to break the same a breaking a wire in you hands by bending it in and out to the spot at the bend fails.

This link is to my photobucket page and the particular album is a NAPA Echlin HEI service bulletin from the early 80s that pretty well walks you checking an Hei component by component. It won't test a module but you need a module tester that some parts houses have for that. There are several pages and I'd suggest saving them to your computer where they may be easier to read. I've use it times over as have friends who I have given copies to. https://s173.photobucket.com/user/mr...library?page=1

I tried your link but there’s 310 photos in there I’m not sure what I’m looking for. I am now going to remove the module and take it to the auto parts store and have them test it. Keep in mind this is a new distributor, new module, cap, etc.

Could having the advance too far be a possible cause of what you’re describing?
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[Livemeyer]

Originally Posted by mr48chev

From what I have seen modules usually fail due to another issue. Bad coil too much resistance in a circuit or ??

The leads on the pickup coil often fail right next to the unit where the continual flexing of the wire due to the advance plate moving causes them to break the same a breaking a wire in you hands by bending it in and out to the spot at the bend fails.

This link is to my photobucket page and the particular album is a NAPA Echlin HEI service bulletin from the early 80s that pretty well walks you checking an Hei component by component. It won't test a module but you need a module tester that some parts houses have for that. There are several pages and I'd suggest saving them to your computer where they may be easier to read. I've use it times over as have friends who I have given copies to. https://s173.photobucket.com/user/mr...library?page=1

I found your NAPA pages. When I was responding earlier I was on my phone and it was not easy to find folders. I am looking at it now, thanks.

[MiraclePieCo]

Originally Posted by mr48chev

From what I have seen modules usually fail due to another issue. Bad coil too much resistance in a circuit or ??

Yes, I was going through about a module a month until I replaced my coil.

[Livemeyer]

Originally Posted by MiraclePieCo

Yes, I was going through about a module a month until I replaced my coil.

I would not think I would need to do that in my case. The first time mine failed it was because it was an old HEI I had grabbed from Pick n Pull. Because of its age and unknown quality, I bought a new distributor. With a new distributor I wouldn't expect a module to go bad so quickly, but it did. Still, I would not expect the coil to be bad, but I'll know if this thing fails again.

[Livemeyer]

I took the module out and had Auto Zone test it. Sure enough, it was bad. I bought their Duralast DR100 for about 25 bucks, installed it, truck is running again. They say it has a lifetime warranty. Hopefully, this never happens again, but if it does, it shouldn't cost me any more money. I still can't help but wonder if there's an issue, since this happened twice and I haven't even driven the truck 500 miles.

[nvrdone]

years ago - 1974 - when I built the 327 I have now, I had problems with the HEI we installed. pulled it out and installed a Mallory dual point distributor and never had another problem if I kept the points adjusted. Finally switched to a Petronix system and the truck runs fine now. Now if I could get it to stop, that would be great. but that's another
story ...

[dsraven]

glad you got it figured out.
curiosity is killing me though. did you pull the coil cover off and ensure there is a ground wire on the coil to the distributor plug? did you check to ensure the wire gauge for the distributor power feed is adequate and the electrical plug condition is also good?

[73kay]

I’ve had a hei dizzy fail me under 2000 miles. And I have another hei that is stock from 85 still working. I think it’s a quality issue but always keep a spare now.