HEI ignition modules failing - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Lobo'74 · 07-13-2005, 11:42 AM

My HEI ignition module dies about every 11 to 12 months. I called the PO on this as he had done the rebuild on the engine. He said he bought the HEI distributor from a chain auto parts store (like Advance Auto) and it had a lifetime warrenty. He just took the whole distributor out when the ignition module failed (yearly) and took the distributor back to the auto store and got a new one.

I found that he had wired the HEI to the tail lights circuit and thought that was the problem. I thought that without a "pure" 12-14 vdc source the module would burn itself out regularly (like it was doing). I rewired the HEI with heavy gauge wire to the unfused block on the stock fuse block. Truck ran great for six months then just didn't have the power it should. I pulled the plugs and found they were VERY, VERY fouled. I got rid of the Bosch platinum plugs and went to NGK plugs. Truck ran great for six months then was hard to start one day and impossible to start the next. Pulled the plugs. Fouled, but nowher near as bad as the Bosch were. Also pulled the HEI ignition module and it was bad.

I relpaced the NGK's with Autolite racing plugs and put in a "lifetime warrenty" aftermarket HEI module to replace the stock AC/Delco module that failed. Truck runs like a champ. Wanted to go out and smoke tires a little

but with my sick tranny I am leaving Truck in the driveway for now.

Could the plugs fouling put more of a load on the ignition module and cause it to go bad? If so then I just keep playing with plugs until I get a set hot enough to not foul but cool enough to not allow post shut down run on or detonation, right?

If the plug fouling would not cause the ignition module to go bad what am I missing? Why do these things quit annually? Is it just to make sure I don't miss the annual anniversary of when I bought it?

Any thoughts?

shifty · 07-13-2005, 12:36 PM

Ignition modules often burn out because they're not properly grounded.

shifty · 07-13-2005, 12:38 PM

Groudning example showing both wires you need to hook up to properly ground is here (scroll between the two posts):

http://67-72chevytrucks.com/vboard/s...15&postcount=7

Someone else stated there is a metal bracket for the second ground that is shown, but I've never seen one.

70 shorty · 07-13-2005, 12:46 PM

I thought I had heard (I am by no means an expert) that the modules basically worked or they didn't work, there really wasn't any in between. Can anyone back this up?

hotrodmtodd · 07-13-2005, 12:52 PM

Heat is the #1 killer of ig mods. Alot of people think they know better, and don't put the silicon grease on the back of the module. It is for heat protection and MUST be used. As Shifty mentioned, the ground strap in the coil MUST be clean, dry and serviceable, the module must be attached with BOTH screws, and the pin count and harness must be the same type. After that, there are many oddball things that can happen with ig mods, but heat protection and good grounds will solve MOST problems. There are many BETTER qualified folks on this board than myself that can help you with the oddball stuff. Good luck, Mike

jhow66 · 07-13-2005, 01:24 PM

Quote:

Originally Posted by shifty

Groudning example showing both wires you need to hook up to properly ground is here (scroll between the two posts):

http://67-72chevytrucks.com/vboard/s...15&postcount=7

Someone else stated there is a metal bracket for the second ground that is shown, but I've never seen one.

here is the metal bracket and where it goes: Also make sure your engine is grounded to frame battery body.

Russell · 07-13-2005, 02:17 PM

I bought myself a tube of Arctic Silver computer processor heat compound, never had a problem after that. The heat compound they give with the modules is cheap crap that is very sub-standard.

**Smitty** · 07-13-2005, 06:56 PM

Shifty is right on. I had the same problem, fortunately it happened near the shop I take it to when I'm to lazy to beat my head against the wall figuring things out. He found that there was a ground from the coil that was absent causing my problem. Haven't had it since!

shifty · 07-13-2005, 07:13 PM

Todd's right about the heat - my truck overheated a while ago and knocked out my HEI entirely. Had to wait almost 45 minutes for the truck to cool before I could crank it back up again.

hotrodmtodd · 07-13-2005, 09:45 PM

Russell: Can you tell me where Arctic Silver can be purchased? It sounds like a very good alternative to the "crap". What company makes it? Maybe I can find it that way. Thanks, Mike
Shifty: Thanks for the positive feedback, it's nice to have 17,000 friends to count on! Take care, Mike

*Tanker350* · 07-13-2005, 10:01 PM

www.arcticsilver.com

hotrodmtodd · 07-13-2005, 11:08 PM

I'll give that a try. Mike

shifty · 07-13-2005, 11:10 PM

It's normally used to act as a thermal transfer paste to take heat off of computer processors. It takes some break-in time before it works at 100%, but that shouldn't take long - one hour of constant driving should do it.

07-13-2005, 12:36 PM	#2
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,373	Ignition modules often burn out because they're not properly grounded. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

07-13-2005, 12:38 PM	#3
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,373	Groudning example showing both wires you need to hook up to properly ground is here (scroll between the two posts): http://67-72chevytrucks.com/vboard/s...15&postcount=7 Someone else stated there is a metal bracket for the second ground that is shown, but I've never seen one. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

07-13-2005, 12:46 PM	#4
70 shorty Where's my beer? Join Date: Oct 2004 Location: Glen Allen, VA Posts: 1,772	I thought I had heard (I am by no means an expert) that the modules basically worked or they didn't work, there really wasn't any in between. Can anyone back this up? __________________ 70 C10, shortstep, .30 over 250,Hurst shifted 3 spd parts hauler. Holley 390, Clifford Intake, Header, ported cylinder head, unknown bigger cam. 79 Corvette L82, 4 spd, black, red interior, headers, flowmasters, and unkown bigger cam. '03 Grand Cherokee Laredo, 4.0 4x4 daily driver. 165K miles, and runs great '08 Tahoe LTZ 4x4 155K

07-13-2005, 12:52 PM	#5
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 918	The Key Heat is the #1 killer of ig mods. Alot of people think they know better, and don't put the silicon grease on the back of the module. It is for heat protection and MUST be used. As Shifty mentioned, the ground strap in the coil MUST be clean, dry and serviceable, the module must be attached with BOTH screws, and the pin count and harness must be the same type. After that, there are many oddball things that can happen with ig mods, but heat protection and good grounds will solve MOST problems. There are many BETTER qualified folks on this board than myself that can help you with the oddball stuff. Good luck, Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

07-13-2005, 02:17 PM	#7
Russell Professional Grade Join Date: May 2003 Location: Fort McMurray, Alberta Posts: 7,915	I bought myself a tube of Arctic Silver computer processor heat compound, never had a problem after that. The heat compound they give with the modules is cheap crap that is very sub-standard. __________________ 1995 Chevrolet 2 Door Tahoe (6.6L LBZ Duramax / ZF6 / NP241 with 1 ton solid axle swap)

07-13-2005, 11:42 AM	#1
Lobo'74 Registered User Join Date: Nov 2002 Location: Charlottesville, VA Posts: 404	HEI ignition modules failing My HEI ignition module dies about every 11 to 12 months. I called the PO on this as he had done the rebuild on the engine. He said he bought the HEI distributor from a chain auto parts store (like Advance Auto) and it had a lifetime warrenty. He just took the whole distributor out when the ignition module failed (yearly) and took the distributor back to the auto store and got a new one. I found that he had wired the HEI to the tail lights circuit and thought that was the problem. I thought that without a "pure" 12-14 vdc source the module would burn itself out regularly (like it was doing). I rewired the HEI with heavy gauge wire to the unfused block on the stock fuse block. Truck ran great for six months then just didn't have the power it should. I pulled the plugs and found they were VERY, VERY fouled. I got rid of the Bosch platinum plugs and went to NGK plugs. Truck ran great for six months then was hard to start one day and impossible to start the next. Pulled the plugs. Fouled, but nowher near as bad as the Bosch were. Also pulled the HEI ignition module and it was bad. I relpaced the NGK's with Autolite racing plugs and put in a "lifetime warrenty" aftermarket HEI module to replace the stock AC/Delco module that failed. Truck runs like a champ. Wanted to go out and smoke tires a little but with my sick tranny I am leaving Truck in the driveway for now. Could the plugs fouling put more of a load on the ignition module and cause it to go bad? If so then I just keep playing with plugs until I get a set hot enough to not foul but cool enough to not allow post shut down run on or detonation, right? If the plug fouling would not cause the ignition module to go bad what am I missing? Why do these things quit annually? Is it just to make sure I don't miss the annual anniversary of when I bought it? Any thoughts? __________________ "Truck" '67 small window '79 350 .030 over, LT1 "clone" Last edited by Lobo'74; 07-13-2005 at 11:45 AM.

07-13-2005, 06:56 PM	#8
Smitty Senior Member Join Date: Dec 1999 Location: Spring Valley, Ca. Posts: 1,136	Shifty is right on. I had the same problem, fortunately it happened near the shop I take it to when I'm to lazy to beat my head against the wall figuring things out. He found that there was a ground from the coil that was absent causing my problem. Haven't had it since! __________________ Smitty '71 Short Fleetside Spring Valley, Ca.

07-13-2005, 07:13 PM	#9
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,373	Todd's right about the heat - my truck overheated a while ago and knocked out my HEI entirely. Had to wait almost 45 minutes for the truck to cool before I could crank it back up again. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

07-13-2005, 09:45 PM	#10
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 918	Arctic Silver Russell: Can you tell me where Arctic Silver can be purchased? It sounds like a very good alternative to the "crap". What company makes it? Maybe I can find it that way. Thanks, Mike Shifty: Thanks for the positive feedback, it's nice to have 17,000 friends to count on! Take care, Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

07-13-2005, 10:01 PM	#11
Tanker350 Account Suspended Join Date: Dec 2003 Location: Palm Desert, Ca Posts: 410	www.arcticsilver.com

07-13-2005, 11:08 PM	#12
hotrodmtodd 'Burban Legend Join Date: Apr 2005 Location: Mingo Junction OH Posts: 918	Thanks Tanker I'll give that a try. Mike __________________ '67 Chevy Iron City Beer Truck (9ft step) '67 Chevy Panel Truck 467 '68 Short Fleet 305v6 '68 McLaren Ramp Truck '68/'68/'70/'71 Burbs 292/366/402/454 '69 C-30 dump '71 C-50 dump and church bus '71 4x4 454 '72 Blazer (w/pop-up camper) $15 x-hooks '66 Chevy II 194/Weber '68 El Camino" 305v6 '69 Skylark 455 Buick '70 Chevelle 427 '71 Cutlass W-31 '71 GTO 400 2x2 "The 51" Chopped '51 Chevy (409) my first car OK Toad, we'll take 'em all... John Milner

07-13-2005, 11:10 PM	#13
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,373	It's normally used to act as a thermal transfer paste to take heat off of computer processors. It takes some break-in time before it works at 100%, but that shouldn't take long - one hour of constant driving should do it. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.



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