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1987 half ton Dodge van

Well, sometime coils go bad, I have experienced several over the years, they often start by developing misfire at higher rpm, and can often be felt to be very hot.
Ha ha, you have obvoiusly not read any of my threads (books)! Like this one: Gm Hei Module Conversion Troubles
As long as you don't bore people like I do, please write as long as you feel like!

A coil has two windings; one primary and one secondary. The way to measure the primary resistance is between the two input posts on the coil (without any wires attached).

On a coil used for HEI, the primary resistance should be 0.5 ohm.

If you measure between an input post and the central post for distributor wire, the resistance is in the region of several thousands ohm.
Some electronic engine management systems use a visibly identical coil, but with different resistances, I have seen commonly used both 0.34 ohm and 1.4 ohm primary resistance.
.

I would guess that the quality of your HEI module also play a role when accepting some leeway in the coil primary resistance.

The HEI module require a good current supply; good ground and the use of a relay to feed the coil and module is good practice.

Olaf.

BTW, I totally forgot: Welcome to the forum, grumpy!

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Aspenized

Thanks for the welcome. That is a very nice setup you built. As for long stories, it is very informative and you have pictures to hold the attention of guys like me. My conversion is kind of spread out with the module on the wall and the rest down on the side of the engine. I am going to go through everything again and I think I will simulate yours if not an out right copy. I am heading to St Louis Mo. in about 30 days from now so I have to get on the ball. With the HEI the slants can’t be beat. I was kid when some one on our block brought one of the first slant sixes home. A bunch of the men were standing around looking it over when one of them wondered out loud how long an engine like that would last. I wonder if he lived long enough to find out.

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1987 half ton Dodge van

Grumpy: I also recall two times that conversation took place with hoods up in ’59 or '60. One centered on a FWD Saab 93 with a three cylinder two cycle engine that left’em scratching their heads, and a Toad with that slanting engine, same thing, wondering how is that thing ever going to make it to 100,000 miles without wearing the bores egged shaped and burning oil…

I guess they forgot about all the V8s that had been navigating the hinterland for the previous thirty years or more in a Ford, or Caddy. LOL

I suspect they are also all gone excepting my soon to be 90 father.

Bill / Grampy

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67' Dart GT Convertible; the old Chrysler Corp.
82' LeBaron Convertible; the new Chrysler Corp
07' 300 C AWD; Now by Fiat, the old new Chrysler LLC

Well, yes, so?

As you become familiar with the forum members, you will find there is (or should be) no fixed recipe on 'How To Do Everything The Correct Way' here. (with a couple of exceptions!) We all have our different preferences, some are restoring a car to mint orginal condition, others - like me - are happy to have a running daily driver with a SL6! Some of us have 14 thumbs and have to use external forces to get things done, some are pro mechanics, many of us like to make things without caring how the end result looks to others, as long as you are pleased yourself. Please don't ever hesitate for a second to share your work with us! We may laugh with you!

You will find a 'Frequently Asked Questions (FAQ)' as a 'sticky subject' in each section, where most things are answered even before you ask! The search function is very powerful, try any subject and be surprised. The accumulated wealth of info in this forum is staggering, there is no other forum like it, use it!

Olaf.

Forgot: Please give feedback when following/ignoring advice from members, too many forget to tell how it ended!

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Aspenized

Olaf, Thanks for the refresher on the HEI. I looked over your linked thread once again, and it is cool for sure. Here is a question for you:

I have an 8 pin HEI and matching coil currently on my car. There are some interference problems developing between the VR pick and the HEI creating spurious RPM signals. I have been told the HEI might not be strong enough for the turbo set up, so was considering replacing the current NAPA HEI with the parts from this page:

http://www.shopatron.com/products/categ ... 6690.0.0.0

The parts that I would get would be the 8 pin module and the coil at the bottom of the page. Are they really any different from NAPA parts? Are they better? Stronger? More voltage? ETC. Or are they same part with Petronix labels? If they really are better, then I am interested. Hopefully the difference might not have the same interference pattern as the current one.

Sam

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Grumpy, I have to steal your thread for a moment, I hope you forgive me for that.

Sam, I am not familiar with the 8-pin modules at all, and I am afraid the same goes for your MS setup. That said, let's look at the hardware in general. The module's main job is to control the charge/discharge sequence for the coil. One of the reasons for replacing the stock Mopar electronic ignition unit, is that a HEI setup give you a longer spark duration. The intensity of the spark is regulated by the coil's construction, and looking at the data for different e-core type coils, apart from voltage output, there is also a marked diffrence in the spark duration times that the coils are capable of, when comparing standard and hi-performance coils, also between the brands. The Pertronics modules may give the possibilty for an even longer duration spark, I don't know what makes them better, people generally seem to be satisfied with their performance, though. The alternative to a long-duration single spark is a multi spark unit like the MSD. Then again, I think the Buick GN 3.8 turbo engines used a stock HEI setup, with great success. I would guess ignition problems in a turbo engine in general kick in at high boost and high revs, and above 3000 revs the MSD is just an ordinary single-spark unit. I think the quality of the coil is more important than the module. Electronic modules usually work well, or they don't work at all.

I can only comment in general to your problems:
Do you have a hi-performance coil, matched to the module, and good spark plugs and plug wires?
Do you have separate, well grounded feed circuits - using high quality relays - to the MS and ignition circuits?
Unless your problem is a known issue with that kind of MS/ignition setup, you have a big elimination process ahead of you. In the part of the circuit where you suspect he problem may be, is it possible to substitute one wire at the time with a shielded one?
Can you mount the module inside a ventilated box/cage construction, thus creating a faraday's cage to eliminate intereference/electronic noise?
I don't know if the last point will help you much, my construction is unintentionally a faraday cage, on the other hand my coil is halfway inside the cage too! The minimal distance between module and coil in my setup means nothing at all for the function, and the same goes for the stock GM setups. I have an ordinary Standard LX-301 module, a Standard CH-410X dizzy cap with a NAPA-Echlin MO-3ooo long-tip rotor, a stock plain Ford e-core coil, Magnecor spark plug cables to NGK UR45IX plugs - pregapped at 0.460, and I never had a miss. (just some jumping around because of a slack timing chain!)
But, I have no turbo.
Question: Why an 8-pin module, is that necessary for interacting with the Megasquirt?

Olaf.

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Aspenized

Thanks Olafla, The 7 and 8 pin are needed for timing control. Or at least that is my understanding. I have an 8 pin because that is what the Buick in the junk yard had. All parts are new. I mainly wanted the wiring harnesses.

Faraday cage is an interesting idea. I am glad to know the GN used a stock HEI. I wondered about that. All cables are shielded. All grounds are good and to a central point, soldered and crimped connections. I have not applied capacitors to things yet. I can eliminate the problem with filtering in the tuning program, but would like to get it smoother with better hardware if possible. All ignition parts now are sock NAPA parts for the same application, I think a 93 Buick Roadmaster. Magnacore wire. NGK plugs with few miles. They are gapped at 25 at the recommendation of Peter Florance. This narrow gap is for the turbo.

You can PM me if you wish to continue without hijacking this thread. I am really trying to find out if the Pertronix parts are made in the same factory as the NAPA ones, or if they are different and better.

To the point of relays in the power circuits, I have a dash board switch to turn on a relay which turns on the fuse block for the ignition. Is this OK? It one of the heavy duty relays. Maybe 60 AMPS?

Thanks. Sam

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