[Inogame]

Originally Posted by Richie Hoffman

Glad it’s not only me with defective parts just had 2 msd billet ready to run bad and 3 dui performance distributors and a melling select oil pump bad after 1500 miles all different engines

This reminds me I have a DOA Ready-to-run that I need to send to MSD.

Ended up stabbing an old HEI and have had no problems.
Forgot the other is sitting on a shelf. oops.
Big $ sitting, I need to get my butt in gear.

[adynes]

Originally Posted by Sun Tuned

Friend has a GM crate 350 for a lil 56 he has. Runs like total garbage. Has exactly 0 miles on it. Fresh out the crate. Bout 10 mins runtime. Wants me to see if I can figure it out. So I says I'll give it a shot.

Check timing.
At 10 degrees. Go to restart.
Hit key to crank, loud report out of tailpipe.
$&@$, try again, big flame out the carb!

Ok....

Let's pull the whole HEI and go home with that and have a look.

Looks good on machine.

Any takers?

What combination of trigger coil and ignition coil polarities does his distributor have? Is it possible he has a combo different from the standard Chevy spec stuff? Did his distributor come with the crate engine?

I knew from my megasquirt project that there were different pickup coils, but wasn't sure why, so I did some Google searching last night to try to figure it out. Discovered a lot of new info that I didn't know before, like that there are two different hei ignition coils, wound opposite directions. Sounds like some people have problems if the polarities aren't correct, while others can run odd combinations without issue. Interesting stuff to read. Noticed a lot of the older threads had many of the same people who have commented in this one

["QUICK-SILVER"]

Can you change terminals on the pick-up wires and run a 5 pin module leaving the 5th pin disconnected?

They were the last of the simpler modules made/used by GM and would most likely be easier to find.

Carbureted truck engines used them in the 80's. Carbs had wires but weren't computer control fuel mix. Thinking the small computer just did spark-retard. Distributors still had centrifugal and vacuum advance.

Bunch of those distributors got swapped for the older 4 pin when the timing control computers started acting up.

Clay

[Ben M.]

Originally Posted by "QUICK-SILVER"

Can you change terminals on the pick-up wires and run a 5 pin module leaving the 5th pin disconnected?

They were the last of the simpler modules made/used by GM and would most likely be easier to find.

While I don't see any reason why it wouldn't work, I would question how easy they are to come by in a "doesn't suck" form these days. Maybe if you go junkyarding it's another option but I'd be wary of trusting what the parts stores deliver for that not so common ignition module.

[Sun Tuned]

Matched pickup coil and in cap coil to application.
Yes HEI that came with crate 350.

Clay you actually jump the pins. Yes we used to do that all the time on the 5 pin chevy trucks a lot. Wow hadn't had anyone ask about that in like 20 years. Thanks for the memories.

Little easier to come across, most don't know you can jumper two pins and it works fine. Then again most thought they were not worth fooling with in first place so that might figure in too.

[Schurkey]

There are TWO kinds of 5-pin modules, and three module-retard systems that use 'em..

One of them gets a + signal to the fifth pin to retard timing, the other the fifth pin is grounded.

["QUICK-SILVER"]

Originally Posted by Sun Tuned

Clay you actually jump the pins. Yes we used to do that all the time on the 5 pin chevy trucks a lot. Wow hadn't had anyone ask about that in like 20 years. Thanks for the memories.

Little easier to come across, most don't know you can jumper two pins and it works fine. Then again most thought they were not worth fooling with in first place so that might figure in too.

Some of the early Astro vans used the same 5 pin module. Seems like the extra lead wire, to timing control, only had three wires. I know I left the harness connector unplugged on them and spliced two of the wires together. The third wire wasn't used. So I'm thinking the spliced wires completed one of the pickup wires and the empty/unused third wire went to the 5th pin. And seems like if you grounded that extra wire (5th pin) it would back the timing up 10° or so.

Been to long to say anything definitive on it though. Just thinking unpopular as they was back then....Might be some NOS stuff hiding out there some where. Or at least some better old stock repops.

Years ago (spraying nitous) I had a 5 pin in the TA that grounding the 5th pin would pull timing out. Can't remember if it was one of the truck fives or came out of something else.

Memory recall just ain't working like it use to. I'd like to have one of the ground to retard timing modules now. Just for hot starts on a high CR 400.

Any info/enlightenment on this would be greately appreciated
Clay

["QUICK-SILVER"]

Originally Posted by Schurkey

There are TWO kinds of 5-pin modules, and three module-retard systems that use 'em..

One of them gets a + signal to the fifth pin to retard timing, the other the fifth pin is grounded.

Apps for them is what I want to know. For hunting old stock or used.

Keep it coming
Clay

[Schurkey]

Originally Posted by "QUICK-SILVER"

Apps for them is what I want to know. For hunting old stock or used.

Keep it coming
Clay

I never did have vehicle applications.

This will give you a quick summary, though:
https://www.enginelabs.com/news/chev...ber-reference/

The five-pin control module was introduced in 1978 and the original version included a provision for connecting a knock sensor. This evolution was an attempt at electronic timing control. There are three different versions of the five-terminal control module. The three different types are not interchangeable.

HEI/EMR Electonic Module Retard used a wire connected to a switch or to an electronic control package. Under certain conditions, the switch or control package will ground the wire, which triggers the retard feature built into the distributor module.
HEI/ESC Electronic Spark Control used a knock sensor and an electronic controller. The knock sensor sends a voltage signal to the controller, which sends a voltage signal to the distributor module, activating the retard feature within the module.
HEI/ESS Electronic Spark Selection used an outboard electronic decoder which receives voltage signals from three sources: a manifold pressure switch, the distributor pickup coil, and an engine temperature switch. The decoder processes the information and provides a voltage signal to the distributor module to adjust the amount of advance/retard.

So far as I'm aware, there are TWO modules, which service the three systems. A module that retards when grounded, and a module that retards when it receives a voltage signal.

[70GS455]

Originally Posted by "QUICK-SILVER"

Apps for them is what I want to know. For hunting old stock or used.



Keep it coming

Clay

1985 Chevy C10 305 Vin H

Standard motor prod LX331

Sent from my SM-T817V using Tapatalk

[smasse64]

Thanks to all...esp Suntuned...you really have the equipment and knowledge to figure out what is going on with these newer HEI modules and I hope you will be able to give the whole GM hobby some recs. of what units are worth buying as these Autozone pcs of crap are not good or safe...to lose my engine while traveling at 70mph on a crowded highway this summer, maybe going to Gettysburg POCI show, is NOT very comforting!!!!...I did contact Performance Distributors (DUI) and they did say their module is made in the good ole USA!!!..They claim small % of failure rate, not enough to result in look at product design..although conversely, they do not have enough Confidence in their HEI modules to match the Echlin 5 yr warranty...and at $55, might still be worth the piece of mind on a fast or crowded and hot highway road trip this summer!!
Suntuned: Could you please keep us all informed of your progress on this?...

Also, Suntuned, the HEI you did for my 326 pontiac lemans convertible in 1999 or so was converted over by me to an oil filled coil to keep the module from overheating by removing the coil from under the cap...but i wanted to ask about a thin black plastic button-like pc that came out from under the weights area...it looks like it was some type of wear surface for the unit to spin on..looks like two of them there...is a missing one a problem and if so, where can i get replacements??..Thanks Sun....

[Sun Tuned]

Steve pm me an address, those are the weight pads. Got plenty. I'll get some in mail in morning.

Bought a module from a different napa. Different distributor, same issue. Did this yesterday. Took it back.

Wanna talk Standard ignition? Switch gears a bit. 1966 426 Hemi Satellite. People up the street bring me a dual point distributor and two Carter afb's. Told them get me a set of points n condenser and bring it over and I'll get em fixed. Go to put new points in. Won't fit. Chryslers have points that the pivot side goes over a steel post on the breaker plate. Ha, check numbers, yep right number, right points.

Post was .006 larger than the hole in the points. Filed the originals and put em back in. Checked original condenser and re used that too.

These people making this stuff would have been hell in high school. If your gonna copy someone else's stuff at least copy it right.

[Sun Tuned]

Two sets of points(was a dual point distributor) they knew what I meant.

[77 TRASHCAN]

Lol, about 2013 I was helping my (now late) good friend work on his 72 GTO. Big part of laugh, was that I didn't need bifocals the last time I installed points!

Well anyhoo, I'm trying to stab my good old Allen wrench in the adjustment bold...key word was try.....
The BW point set didn't use the old size adjustment bolt, it was metric.....

[Formulajones]

The points I use from Accel still use a standard allen wrench that works fine, but the adjustment is also slotted for a screw driver, which is what I use anyway. Way easier than dinking around with a little allen wrench.

[77 TRASHCAN]

Originally Posted by Formulajones

The points I use from Accel still use a standard allen wrench that works fine, but the adjustment is also slotted for a screw driver, which is what I use anyway. Way easier than dinking around with a little allen wrench.

I meant to mention in my post, that one of the every-day special tools that used to be carried by EVERY parts store was a flex shaft screwdriver with correct Allen wrench on end, for adjusting GM points. I see them in piles of junk tools at swap meets, no one much knows what they were used for...

[1968GTO421]

Originally Posted by 77 TRASHCAN

I meant to mention in my post, that one of the every-day special tools that used to be carried by EVERY parts store was a flex shaft screwdriver with correct Allen wrench on end, for adjusting GM points. I see them in piles of junk tools at swap meets, no one much knows what they were used for...

Thanks for the memory. Looked around and I still have one in my older toolbox. Now, are there points that I can actually use this tool on that aren't metric?

[68 Firebird]

Even though I am running a DUI HEI. I still keep a spare Module, Complete Cap and rotor assembly including coil and low resistance button in my tool bag in trunk. I must be paranoid. Gerry

[Sun Tuned]

No Gerry, it's called being smart and prepared.

[Formulajones]

Originally Posted by 77 TRASHCAN

I meant to mention in my post, that one of the every-day special tools that used to be carried by EVERY parts store was a flex shaft screwdriver with correct Allen wrench on end, for adjusting GM points. I see them in piles of junk tools at swap meets, no one much knows what they were used for...

I have one of those