I have an HEI in my '71 (SBO-4bbl), believe it is a '74-75 model year (not sure how to tell) and about every 6 months the module just dies. It is warrantied so I just get another one but it is becoming a PITA. The module passes bench testing at the store but only replacement corrects the problem. At the advice of a friend of mine I ran a ground wire from the back of the block to the firewall hoping that might alleviate or fix the problem completely, and the module did last a few more weeks but not sure if that really helped in longevity. It is an Auto Zone Duralast part (AZ part number DR100) and if/when I replace it this will be #3 in the past couple of years.

Failure appears without warning, no hard starts, sputtering, missing, etc., it just decides to not start. Since it has happened so many times I just throw my timing light on it and crank it, no light=no spark and I make the trip. Module is not melted, corroded, warped, burnt, etc., center contact with the coil is clean, cap is not burnt or corroded. Pull and reseating the plugs in the module has no change.

So I need some suggestions on;

• Different parts manufacturer
• Maybe the wrong part (how can I tell what year the distributor is, hopefully without pulling it out)
• Other testing that can be done
• Other possible causes
• Maybe the coil is too hot or is bad causing the module to burn up?

I am out of ideas short of carrying a spare with me everywhere.

Thoughts?

 

yeah, your wires feeding the pickup coil have flexed to death. Seen that before.

When you replace the module you move these wires... and for a while it behaves again.

Because you replaced the module, and suddenly you have spark, you assume the newer one works better. Remember, though, that the module tests OK at the store, only fails in the car. What is different? The trigger signal.

I bet if you find no-spark and put your hand powered vacuum pump on the advance canister and exercise it a bit then it develops spark again. Because this moves the pickup coil and flexes the wires into contact.

You do have to dismantle the dist'r to replace the coil, good opportunity to refresh the grease and redo the bushings if they look iffy. If you look and feel super carefully at the coil you remove you will probably find the broken section of wire. In my case, I tugged at the pickup coil's wires and the broken one finally separated, providing the clue I needed.

Is there a youtube dist'r dismantling 101 or do we need to make that?

 

Good thoughts Octania. I didn't take it that far because the distributor was redone recently (2-years ago or so) BUT I can't say if all of the parts were 100% fresh when that happened. I am about 90% certain the advance weights and springs have been modified and I think that the vacuum advance canister MIGHT be adjustable so that could possibly explain why the wires may be impacted and supports your hypothesis. Because of the dubious 'quality' of imported parts I often look to defects before sussing everything out.

Been a while since I pulled a distributor but looking around on the Interwebs it all came back to me. I didn't see any Olds specific refresh videos but a GM HEI between breeds is not so different that I can't figure it out. Other than the obvious that it runs the opposite direction of a Chevy HEI I don't see any huge differences, but correct me if I am wrong.

 

couple things come to mind. First, read this:

http://www.chevelles.com/techref/ftecref5.html

If there is a question regarding the harnesses, replace them.

What kind of coil are you using? Is it fresh? And of good quality? Are you using a low-ohm bushing? (you should)

Do you use the heat sink paste on the module? (And not die electric grease or other than the sink white paste?)

Use the NAPA module, all the parts stores ones are junk.

Make sure your pickup wires are wired correct for the coil you have.

.

 

By chance is your charging system overdoing it a bit? I heard somewhere the modules don't like anything over 14.5 volts. My cutlass would see 15 volts or over on the freeway so I switched to a solid state regulator.....now it's rock solid at 14. And I'm running a Chinese hei so surely the module is a cheap pos haha! But it's been working for 5 years now with the new reg

 

Mark the gear and shaft before removing the pin so that you put it back on same way, not 180 off- the hole is never PERFECTLY centered.

 

Recheck the grounds too...ALL of them you can find...including the neg battery cable to the block...clean and tight! Good advice on the higher quality modules too, highway star. I steer clear of the big box houses of chinese junk at all cost. ITS ALL JUNK! The heat-sink paste is critical as mentioned. 9 out of 10 times, if its not the open wires that Octania describes, its lack of a good ground that takes out the module. This holds true with most electronic distributors. You are feeding this "new" distributor with a new, keyed, full 12 VDC power source, right, and not using the original points resistor feed wire???

 

@HWYSTR455
http://www.chevelles.com/techref/ftecref5.html - Keeping that reference! Thanks!

If there is a question regarding the harnesses, replace them. - I might do this for prevention of future problems.

What kind of coil are you using? Is it fresh? And of good quality? Are you using a low-ohm bushing? (you should) - Factory coil, unknown age, unsure about the bushing. What brand coil should I consider if replacement is needed? Let's assume Napa; ProFormer or Echlin or should I go with an MSD?

Do you use the heat sink paste on the module? (And not die electric grease or other than the sink white paste?) - Yes I do.

Use the NAPA module, all the parts stores ones are junk. - Noted, I will add that to the shopping list. Are you referring to the Napa ProFormer or Echlin series?

Make sure your pickup wires are wired correct for the coil you have. - Will do.

@DJS70cutlass
By chance is your charging system overdoing it a bit? - The volt gauge shows 14 (idle) - 14.5 (under engine load), never runs over, drops to 12.5-13-ish at idle with full electrical load. Voltage regulator was replaced over a year ago to correct the old “voltage twitch” syndrome, voltage is stable now. The ICM has been replaced twice since the VR was replaced.

@Octania
Mark the gear and shaft before removing the pin so that you put it back on same way, not 180 off- the hole is never PERFECTLY centered. - Noted. The MSD videos teach at a 3rd grade level but are pretty good. I don’t turn a wrench for a living so I need all the help I can get.

@droldsmorland
Recheck the grounds too...ALL of them you can find...including the neg battery cable to the block...clean and tight! - Done all are good, battery to frame and block to firewall.

You are feeding this "new" distributor with a new, keyed, full 12 VDC power source, right, and not using the original points resistor feed wire??? - Using 12v off the battery (has inline fuse, yes checked fuse and is good) original points wiring has been gone for almost 30 years.

 

Yeah, the harnesses are inexpensive insurance, and many times the rebuilt or even aftermarket distributors use crappy harnesses.

I prefer the Echlin modules, when I ran HEIs, that's all I used.

Coils, I like the MSD ones, but the NAPA ones are fine. They may even be the same manufacturer, MSD could rebox, and there aren't many manufacturers. Definitely use the low ohm bushing with the MSD coil. (I prefer to use it regardless of coil make/brand)

You mentioned your grounds are good, and you have one from the batt to frame, and block to firewall. Just to eliminate the possibility of me not understanding correctly, you do have a ground from the engine to the frame, correct?

I run a 2g from the batt to the frame using a 2g lug, which is screwed to the frame where I cleaned the frame, then run another 2g from that point on the frame to the block, using lugs. I also run a 10g from the batt to the fender, and a 10g from a intake accessory bolt hole to the firewall. I use that point on the intake as a common for ground for other engine accessories. (This is just an example)

I got tired of how close the HEI cap was to the firewall, how it crowded stuff at the back of the engine, and from in-cap coils failing. I went to a small cap aftermarket distributor at that point, and an external coil, and will never look back. The aftermarket distributors are more accurate when dialing in the advance curve. I use a Summit E-core coil which is black and has no markings, they are like $30 new. (again, just an example)

The distributor gear has a dimple on it on one side where the pin hole is, and that side should face to the side the rotor points.

Depending on where you pull the 12v source, it may not have power when cranking, or full power. There is an 'IGN' tab on the fuse box that prevents any question there, but if you have a American AutoWire engine harness, it should be full 12v while cranking right off the harness, they bypass the resistor wire if you chose the HEI option. If not, you can pull the wire out of the connector at the firewall and run a new wire.


.

 

Note on my personal experience on in-cap HEI coil failures. They would last about 6 months. Then, once they started to get hot, they would slowly start providing weaker spark, to a point where it would miss, then not work at all.

Took me forever to figure it out, roadside repairs suck, but I would wiggle wires, replace modules, even had a spare dizzy in the trunk. I would do the repair, which allowed time for the coil to cool off, it would start and run, but finally die again, where I would go through the same cycle. (I would leave the cap and coil on the car when I swapped distributors)

That usually started happening after about 2 hours of drive/run time, so I never really knew how long it was before it started to go bad. Most of my driving was around town, less than 2 hour run times, frustrating. The 'more-bad' it would get, the shorter that 2 hour time became.

I never really figured out the root cause, I gave up and went to an aftermarket distributor. But I believe it was a combo of crappy modules and defective/crappy coils.

At one point, right before I installed the new distributor, I had replaced the module with a NAPA one, and a NAPA coil. That was running fine all the way up to me swapping out the distributor, so not sure if that actually solved my problem or not. (I believe it may very well have, but already had purchased the new aftermarket distributor, and wasn't going to take a chance)

.

 

You've got many good suggestions. Here's mine:
Be sure to use the correct paste under the module. If you think that the secondary voltage is getting into the module, switch from the in-cap to the divorced coil. If you are still using the mechanical style voltage regulator switch to either an alternator with the internal regulator or use a separate solid state regulator.

 

I keep coming back to "the module tests OK at the store" yet does not work in the car...

which leaves trigger, grounding, or perhaps coil.

 

If the module test is accurate, you are correct. My comments were based on a failed module. But if it tests good why would it be replaced under warranty?

 

All good tips. Yes I agree with the bad coil too. Ohm it out hot and cold between the wingdings and to ground and see if you have something going on between the primary and secondary wingdings? Could very well be breaking down under heat. Gremlins! Fun stuff huh. You will feel real good when you find this one.

 

@HWYSTR455 - ...you do have a ground from the engine to the frame, correct? - Yes there is.

@OZZIE - Be sure to use the correct paste under the module. If you think that the secondary voltage is getting into the module, switch from the in-cap to the divorced coil. If you are still using the mechanical style voltage regulator switch to either an alternator with the internal regulator or use a separate solid state regulator. - Yep, correct paste is being used. I have thought about moving to an internal regulator but since the voltage is stable, I am leaving that alone for now.


But if it tests good why would it be replaced under warranty? - Let's just say that the kids at the auto parts stores are not the brightest bulbs on the string. Plus, they really don't care...

UPDATE:

Several things happened-
Sunday morning I went to the Turlock swap meet this weekend and found a completely rebuilt HEI distributor that included ICM, coil, cap, adjustable vacuum advance, and nice housing, everything. I went ahead and grabbed it, has Napa Echlin internals...$60. I figured at the very least it was worth the price in the parts alone.

Sunday afternoon I started hashing things out;
Pulled the cap and rotor and looked around at the guts and though I didn't find anything broken, but I didn't dig too deep. I was going to just pull the old distributor out, swap the springs and weights and drop it in but as I was running out of daylight. I put the cap and back on, tried to start and I had the timing light attached, I was getting a strobe but didn't even try to start. I figured what the heck, put the new cap/coil and rotor (left the ICM that I thought was the culprit), put the wires back on, cranked her up and she started instantly! After a nice warm up I took her out and she seems to run perfectly, in fact she might run a little better.

Ok so, is the problem really "fixed?" I will say for now, yes. I still want to pull the old unit out at some point and really go thru it. Since I am going to replace the intake manifold in a couple of months I might do it then.

Also as a clarification, I talked to the previous owner about it and got more information. The cap and rotor were new but the coil is probably over 20-years old if not older.

 

I haven't seen it mentioned yet but you could also wire the module externally on the firewall and remove it from the heat inside of the dizzy completely. I had a ford probe I had to do that on. Did everything you are doing, kept replacing modules that would test good, then not start hot. At first I was putting ice on the cap and it would get it to start again after about 10 minuts and then that got old and then summer came around and I was really screwed. Once I put the module on the firewall I never had a problem starting it again hot.

 

After a few days, problem repeated itself. Pulling the distributor, swapping the weights and putting the new one in.

 

If I didnt mention it before make sure the engine block has a good ground path to the battery via the battery neg cable as well as a secondary strap to the firewall. Have you probed the voltage signal going to the module? If so what was that voltage reading at idle and at 2000rpm?

 

petronics

 

I haven't said a word since November 2nd.

I'll say it now: Why not get a points distributor and replace that "reliable" HEI unit?

- Eric

 

why not fix the problem? replacing the hei with "reliable" points is going backwards, imo.


bill

 

I'm just making the point that someone in the past went out of his way to "improve" this car, and the result is Chris pulling his hair out.

Sometimes simpler really is better.

- Eric

 

and fixing the problem is best.


bill

 

All grounds checked and good. I would need to recheck the voltage but I am going to yank out the current HEI and put in the new one when I have a couple hours of spare time.

I have heard good things about their distributors, and I might go that route at some point but but for now I will keep what I have.

The only thing is I hate points. Back in the day I replaced the original points distributor with a Mallory dual-point but never could get it quite right. Dropping in the HEI was a simple solution at the time that worked well. Since the rebuild in 2012, an HEI was installed but turns out it was cobbled together with a number of dubious electrical parts of unknown age and origin which I am pretty certain is the root cause. I do have another completely re-done HEI so except for swapping the weights and springs, I am ready to proceed. Troubleshooting this problem is not making my hair disappear, I like that challenge, it is my day job and trying to find the time...

 

Not sure it was mentioned with all of the "ground" posts,
do you still have an internal HEI COIL ground. Seen
a few replacement distributors lacking the internal flat ground
that goes from the coil mount screw to the center pole.
Will kill the module if not there.

 

Got it pulled out, now just need to change the weights. The vacuum advance has an "18" stamped on it which I assume is 18* of total crank degrees of vacuum advance?

I also believe that I found the real problem. It looks like one of the has backed out of the plug which would explain why it would run for a while then just stop.

More info on the distributor origins:
This was the same exact distributor that was installed back in the mid-80's and has had no other mods or anything done to it. The center shaft feels like it has more play than it should, so I believe that it is simply worn out.

On pic 3 it looks like there might be some electrical residue from arcing? I have seen similar on other electronic board that have burned up.

 

I would say that is the most likely cause of your issue. Try reseating the terminal and make sure it is secure.

 

the connectors should each have a little tang on them that sticks up some, that is how the terminals are retained into the connector housing. bend it up a little bit(about a 30 degree angle relative to the terminal body) and give the terminal a little squeeze with a needle-nose pliers, to give it a better grip on the module terminal. glad you finally found the trouble! this was why the modules always tested good at the parts store.


bill

 

I am getting ready to install the distributor and I need to put the oil pump drive shaft back in and reading on CO one danger is dropping the shaft into the pan, something I obviously don't want to do.

Is there a good method of placing the shaft into the pump blind since the engine is in the car?

Big thanks to everyone who has helped so far.

 

There is a retaining clip on the on shaft that keeps it in the distributor, other words it should NOT fall out when installing. Most people have the problem of pulling the dizzy out and the shaft stays. As long as yours is staying in the dizzy with minimal play in the shaft you should have no problems. Just wiggle the body down the hole a bit and turn the the shaft back and fourth till you get the gears lined up, then rotate the body down to seat it all the way. Other thing to look out for is make sure you leave yourself enough space between the firewall and vac advance to adjust the timing to where you need it.

 

Retaining clip is not there, the shaft just slides in and out. Where does one get the retaining clip and what does it look like?

 

I think you have that backwards. The retainer keeps the shaft in the oil pump so when you pull the distributor the shaft stays in the block instead of coming out with the distributor.

 

That is what I read the most, but still the question remains...how do I drop it into the oil pump without loosing it? ...other than 'very carefully'...

 

Pump drive should go on with the pump.
Tried before to go the other way when I was young and impatient, does not work so well. Those clips space the pump drive correctly between the pump and distributor. If the drive goes all the way down in the pump, it will not engage correctly in the distributor.
MY opinion is jack the engine and pull the pan, put a brand new oil pump drive in correctly, from the bottom. While you have the pan off, get the clips out of the pan. Anything else is doing it wrong.

 

Dropping the pan seems a bit extreme just to get the oil shaft and distributor back into the engine. The oil pump has <5000mi on it, did not intend to replace the pump.

Just for clarity; I pulled the distributor, the shaft came out with it, removed the shaft from the old one (distributor), and I am putting in a new distributor and want the oil pump shaft back in the pump. Since the location of the distributor is a bit of a blind area, I want the best way to a) place the shaft into the oil pump without loosing it, and b) install the new distributor without causing a new problem, i.e. forcing the shaft down further or dropping the shaft in blind and loosing it.

 

You are correct I was thinking the gear as soon a I heard falling off.

Well If you don't want to drop the pan you can install it the same way it came out stuck to the dizzy. Only problem is that clip is now floating around in your pan.

 

hey Chris did Brian put that engine together? Did he forget to install the clip on the oil pump/distributor drive shaft? if so there won't be a clip. But should be. A simple item to miss on an engine assembly. Not picking on Brian we all could make this mistake.

Just a thought.
Larry

 

He did put it together, I am going to give him a call and see if he did put the clip in. Either way do I need to place the retaining clip prior to dropping it into the pump?

 

You'll have to remove the pump to get the clip back between the pump and the block where it's supposed to be. And OIL the hole on the dizzy gear and shaft really well before installing so this doesn't happen again.

 

You don't need that clip. It's an assembly convenience item.

Use a magnetic parts fetcher. Stick the drive shaft on the end of the magnet, lean over the car with a flashlight and feed the shaft down through the hole. Feed it down straight and it'll go right into the oil pump. Just make sure it is fitted into the pump (won't go down any further) before pushing sideways on the magnet to release.

Done it dozens of times.

The clip in the oil pan - if it's even there - is of absolutely no concern. That's what the screen on the pickup is for.

Aftermarket drift shafts don't have the retaining clip in them. IMO that clip is a terrible idea. Most often the shaft gets wedged into the dizzy gear - just like you experienced. With the clip in place it's a real challenge to get the dizzy out.

Also, check the engagement between the shaft and the dizzy gear. You may need a new dizzy gear if the engagement is getting loose.