Ignition Mudule
Melting Slicks
Joined: Dec 2015
Posts: 3,181
Likes: 732
From: Texas City, TX Texas
"Another module killer is a dead spark plug or one with a spark plug wire that is arcing to ground."
Hadn't read that yet, what say? We did think possibly one header tube was cold.
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
Anything with high secondary resistance....bad plugs wide gaps, bad wires will shorten a module's life. Under warranty back then under an ignition module failure, GM wanted plugs and wires replaced too.
Last edited by Mrvettenick; Aug 25, 2021 at 01:35 PM.
Thread Starter
Banned Scam/Spammer
Joined: Aug 2020
Posts: 171
Likes: 52
From: Warren, Mi
Mrvette..... Hmmm that is interesting.... You mentioned wide gap. I am running 45 thousands which is spec..... Should I close that up a little to maybe 40 thousand. Also would advanceing the timing also cause premauture failure.
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
.045 is std gap for most HEI. Where the problem develops is when people don't change their plugs, and now you have .060 or more. If that what the spec is, then go with it.
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
quote:
"another modge killer is dead sparkplug or wire arcing to GRD".
But basically, when the juice travels from the distributor to the sparkplug and fires it, that is arcing to GRD. I can't see where that would kill a modge. The voltage doesn't care if it makes it all the way to the plug or stops short along the way. As long as its a complete circuit.
However, a loose plug wire that is no where near GRD and can't GRD the voltage, that may do damage to a modge / coil because the firing circuit is incomplete.
Even if the plug does not fire, the voltage is going to GRD in the cylinder head right?
"another modge killer is dead sparkplug or wire arcing to GRD".
But basically, when the juice travels from the distributor to the sparkplug and fires it, that is arcing to GRD. I can't see where that would kill a modge. The voltage doesn't care if it makes it all the way to the plug or stops short along the way. As long as its a complete circuit.
However, a loose plug wire that is no where near GRD and can't GRD the voltage, that may do damage to a modge / coil because the firing circuit is incomplete.
Even if the plug does not fire, the voltage is going to GRD in the cylinder head right?
Pro
Joined: Jul 2021
Posts: 719
Likes: 156
No. Perhaps CF member Big2Bird has; seems he bought 3 or 4 heat sinks. Look under hood & slightly toward passenger side of any of those trucks; both the coil & module are bracketed together. About 12"-18" from dist. Their module is a little different shape than old faithful 4-pin so heat sink requires a different mount hole spacing; simple. You can mount the heat sink anywhere; atop motor, on firewall etc. Module's gonna be lots cooler than mounted on dist body-inside cap.
Daves small body heis & others have been doing this & similar for eons.
Also, from what I can tell, when it comes to GM ignition systems & specifically 4-pin hei, one of the smartest gents in the room is CF member 69427.
Daves small body heis & others have been doing this & similar for eons.
Also, from what I can tell, when it comes to GM ignition systems & specifically 4-pin hei, one of the smartest gents in the room is CF member 69427.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
How Much Horsepower Every Corvette Engine "LOST" in 1972
Joe Kucinski
Top 10 DOs and DON'Ts for Protecting Your Convertible Top!
Michael S. Palmer
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
You know....all of this overthinking is great...but why not go buy a 93440806 GM crate engine distributor and stab it in.....be done with it.
Millions of people have driven around with **** wires, **** plugs....high underhood temps, etc....with HEI distributors for the last 45 years......with zero issues, and you can too.
Unless you like screwing around.....
Since the HEI is self contained.....there is absolutely nothing that can cause its failure short of low or high voltage at the BAT terminal.
The 806 has a nice curve in it too.....
Jebby
Millions of people have driven around with **** wires, **** plugs....high underhood temps, etc....with HEI distributors for the last 45 years......with zero issues, and you can too.
Unless you like screwing around.....
Since the HEI is self contained.....there is absolutely nothing that can cause its failure short of low or high voltage at the BAT terminal.
The 806 has a nice curve in it too.....
Jebby
Last edited by Jebbysan; Aug 26, 2021 at 07:28 AM.
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
Yes it does….a GM one. Brand New…almost certain to work. Whatever is smoking your modules is not worth pursuing to me and it certainly isn’t wires or plugs….total BS. Millions of GM HEI equipped V8’s drove billions of miles in poor tune with a module.
The end game here is to get the car running and reliable, right? Throw the other **** in the trash and start over with a new distributor. There is NOTHING outside of the distributor that causes distributors to fail….or not work, short of voltage too high or too low….
Myself and many others have seen HEI’s function when they really shouldn’t in some of the most challenging and severe conditions….this is why people run HEI’s in some forms of racing, cheap and reliable.
Save yourself the headache. Stick a new one in. GM has installed tens of thousand of these 806 distributors in tens of thousands of crate engines that you see everywhere for the last 30 years. They work.
The Davis DUI looks promising too….but I have never used one….nice that they will curve it for you.
Not being nasty here….you can do what you like….but I told you what I would do.
Jebby
The end game here is to get the car running and reliable, right? Throw the other **** in the trash and start over with a new distributor. There is NOTHING outside of the distributor that causes distributors to fail….or not work, short of voltage too high or too low….
Myself and many others have seen HEI’s function when they really shouldn’t in some of the most challenging and severe conditions….this is why people run HEI’s in some forms of racing, cheap and reliable.
Save yourself the headache. Stick a new one in. GM has installed tens of thousand of these 806 distributors in tens of thousands of crate engines that you see everywhere for the last 30 years. They work.
The Davis DUI looks promising too….but I have never used one….nice that they will curve it for you.
Not being nasty here….you can do what you like….but I told you what I would do.
Jebby
Last edited by Jebbysan; Aug 26, 2021 at 10:15 AM.
Melting Slicks
Joined: Dec 2015
Posts: 3,181
Likes: 732
From: Texas City, TX Texas
I hear ya Jebby, I have had I don't know how many HEI equipped cars in the last 35 years, I wouldn't swear to it, but I don't remember ever having these problems before. I would change the cap and rotor just out of maintenance, but I didn't even know what an ignition module was until recently. I'm not sure what brand new distributor I bought a hundred miles ago, but I doubt it was a 93440806. Wasn't cheap, either. Was a rush job to make it to a show the next day. Is there a tach drive comparable to the 93440806?
Dr. Detroit
Joined: Mar 2012
Posts: 10,097
Likes: 4,027
From: New Braunfels Texas
I hear ya Jebby, I have had I don't know how many HEI equipped cars in the last 35 years, I wouldn't swear to it, but I don't remember ever having these problems before. I would change the cap and rotor just out of maintenance, but I didn't even know what an ignition module was until recently. I'm not sure what brand new distributor I bought a hundred miles ago, but I doubt it was a 93440806. Wasn't cheap, either. Was a rush job to make it to a show the next day. Is there a tach drive comparable to the 93440806?
As a note: I don't care for HEI units.....they are physically big and hard to curve.....I like the small cap MSD stuff with a box and coil. Why you ask? Well....if your MSD quits...it is one of three things that made it quit and you can test what they are in five minutes. I like that idea.....R&R and move on......with an HEI, is it the coil? Is it the module? Is it the pickup? Just like an MSD right.....but no real way to test it easily in the field. This is why I usually just replace them......the customer almost never has a curve or adjustable canister so an 806 with an adjustable can is just what the doctor ordered......you put it in and it runs even better than before it quit...customers like that.
Jebby
Last edited by Jebbysan; Aug 26, 2021 at 11:32 AM.
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
Yes it does….a GM one. Brand New…almost certain to work. Whatever is smoking your modules is not worth pursuing to me and it certainly isn’t wires or plugs….total BS. Millions of GM HEI equipped V8’s drove billions of miles in poor tune with a module.
The end game here is to get the car running and reliable, right? Throw the other **** in the trash and start over with a new distributor. There is NOTHING outside of the distributor that causes distributors to fail….or not work, short of voltage too high or too low….
Myself and many others have seen HEI’s function when they really shouldn’t in some of the most challenging and severe conditions….this is why people run HEI’s in some forms of racing, cheap and reliable.
Save yourself the headache. Stick a new one in. GM has installed tens of thousand of these 806 distributors in tens of thousands of crate engines that you see everywhere for the last 30 years. They work.
The Davis DUI looks promising too….but I have never used one….nice that they will curve it for you.
Not being nasty here….you can do what you like….but I told you what I would do.
Jebby
The end game here is to get the car running and reliable, right? Throw the other **** in the trash and start over with a new distributor. There is NOTHING outside of the distributor that causes distributors to fail….or not work, short of voltage too high or too low….
Myself and many others have seen HEI’s function when they really shouldn’t in some of the most challenging and severe conditions….this is why people run HEI’s in some forms of racing, cheap and reliable.
Save yourself the headache. Stick a new one in. GM has installed tens of thousand of these 806 distributors in tens of thousands of crate engines that you see everywhere for the last 30 years. They work.
The Davis DUI looks promising too….but I have never used one….nice that they will curve it for you.
Not being nasty here….you can do what you like….but I told you what I would do.
Jebby
Tech Contributor
Joined: Jun 2004
Posts: 20,868
Likes: 961
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
Think about it. When you advance the timing, the spark happens at a point when the piston is further down the cylinder. The further down the cylinder, the lower the cylinder pressure, which reduces the voltage the coil needs to generate to jump the plug gap. Easier on the coil, and easier on the module as the internal power transistor sees the plug voltage divided by the coil turns ratio.
I've haven't done that experiment, but cannot see making a difference. But I'm not sure if that makes the OP's situation any better,
Safety Car
Joined: Nov 2005
Posts: 3,532
Likes: 1,185
From: Arizona - If you don’t know CFI, STOP proliferating the myths around it...
As far as a DUI dizzy goes, they sell a good unit and I have one. However, with that said...THEY WILL NOT RELEASE ANY DATA ON THEIR LATENCY TABLE NUMBERS FOR THEIR MODULE. This in itself is total BS! How do you tune a motor without that info? There are ways around this, but it is a PITA, ask me how I know this. I had a long talk with Bob, the owner of Dynamic EFI about this same issue with DUI and he said the same thing, that is BS! This is damn near about the same thing as installing a cam from a company like Comp or whoever and them not telling you what the specs are. WTF?! 
Oh, and one last comment on DUI. Their heat sink compound must be cheap and heard of several people having to replace their module several times because they burned up. I took mine apart before I installed it and it was sparse for the compound. I cleaned up everything and used ArticSilver5 CPU heat transfer grease and works just fine. You may want to check that if you buy their dizzy, jus sayin'.
Oh, and one last comment on DUI. Their heat sink compound must be cheap and heard of several people having to replace their module several times because they burned up. I took mine apart before I installed it and it was sparse for the compound. I cleaned up everything and used ArticSilver5 CPU heat transfer grease and works just fine. You may want to check that if you buy their dizzy, jus sayin'.
Last edited by Buccaneer; Aug 26, 2021 at 03:50 PM.
Tech Contributor
Joined: Jun 2004
Posts: 20,868
Likes: 961
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
If the coil and module were designed for a certain firing voltage, which we assume 8 degrees or less, then how much it it going to change? Normal voltage should be 8-12 KV. If it's 10% less, what is that 1kv?
I've haven't done that experiment, but cannot see making a difference. But I'm not sure if that makes the OP's situation any better,
I've haven't done that experiment, but cannot see making a difference. But I'm not sure if that makes the OP's situation any better,
Drifting
Joined: Aug 2019
Posts: 1,334
Likes: 225
I was explaining the physics of what happens in the cylinder and what happens electrically when the timing is advanced, which was the poster's question/concern about module reliability. My intent was to impart some knowledge to the poster so he has a better understanding of his system. Do you have an issue with answers other than a yes or no?
Tech Contributor
Joined: Jun 2004
Posts: 20,868
Likes: 961
From: I tend to be leery of any guy who doesn't own a chainsaw or a handgun.
Apparently it was complicated enough that the poster/questioner didn't know the answer, or how to figure it out.
He now knows the answer, and why. A simple yes or no answer doesn't help the questioner learn something useful, or how to tell if a yes or no answer guy is FOS.
He now knows the answer, and why. A simple yes or no answer doesn't help the questioner learn something useful, or how to tell if a yes or no answer guy is FOS.