1993 SBC with the small HEI Disruptor failing timing modules

R

racprops

Well-Known Member
Here is a problem I almost forgot: I have a 1993 SBC with the small HEI Disruptor, it has been upgraded to a MSI performance Disruptor with the Hoped for but NOT fixed module burn out problem.

I have gone through a bunch of these modules, it will start to misfire, and I would replace it and on I would go. On a trip from Phoenix to El Paso, I used three of them, one by Caste Grandy, then at El Paso and the third after getting back to Phoenix.

Seems MSI use OEM Modules with still fail. Cleaned to mounting area and applied the thermo grease.

I had had a 74 G20 Van with a 350 that on trips to LA needed a set of spark plugs from leaking valve sleeves and oil fowling on one side…and by the return trip they would be fowled again…I had my own sand blaster plug cleaner and carried 4 sets.

I have tried nearly every idea I can, I added pure ground wires from the Disruptor to the battery, I added a 30 AMP relay from the Positive term so it gets pure 12volts and I added a pair of Didoes and a old fashion cap/condenser to block and EMI.

It seemed to cure the problem but I am not 100% sure.

Anyone run into the damn modules failing and any cure/fix??

Rich

This module:
 

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WHICH thermo grease are you using?
distributor thermal grease vs dielectric

Burning Out Chevy Hei Distributor Ignition Modules

bad engine grounds or ,high resistance electrical connections, like coil wires, or a defective coil, and worn ignition wires, bad, battery and engine electrical connections and faulty grounds are primary sources for this problem, the more ohms resistance, in the ignition, system's wiring...
garage.grumpysperformance.com

https://www.enginelabs.com/news/what-i-learned-today-the-differences-between-ignition-system-grease/​


Silicone Dielectric Grease is a temperature resistant material used for lubrication and as a sealant to prevent corrosion. Thermal Grease is a temperature conductive material used to assist with efficient heat transfer to a heat sink with electronic components.

www.fullsizebronco.com

Dielectric Grease vs Thermal Grease

www.fullsizebronco.com www.fullsizebronco.com
 
Understood, I used the grease that came with the modules.

Edit: I also bought a MSI Coil at the same time.

I did at some point read that the 93 G20 Van did have problems with the ignition wiring which is why I added to relay making that part of the wiring only a low current controller of a relay.

It may be a complete repair BUT wanted to look into other repairs like say perhaps a large HEI distributor.

Rich
 
are you using a ballast resistor,
(yes I know the car might not come with one) (but adding one significantly reduces heat in the module)
A ballast resistor reduces current to ignition points once the vehicle starts and the key is in the “ON" position. So when the vehicle is being cranked, full current. When the engine catches and the key is released and left in on position, current is reduced
 
I remember that old setup And a old problem was car started and died the second the key was released, that was a bad ballast resistor, the coil had power by the starter control but the resistor was burned out so no power once the start cycle was over.

So I can run a ballast resistor on a modern system??

Rich
 
yes and they are fairly inexpensive, it will reduce the heat the module sees, and it should not cause any issues but if it does, or doesnt, its a fairly fast and cheap test so your not out much money, if it fails to cure the issue,
let us know what you find and how it works for you in that application
 
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Thanks that should work great as the MSI Coil is a high output so even as a full time resistor should not really inped the spark...
 
Im not sure a resistor is a good thing since the HEI ignition module should have adaptable dwell?
I have trouble shooted several pre HEI vehicles that were converted to HEI ignition there they left the resistor/wire in use and the spark was very week especialy at higher rpms.
 
Yes the timing is PCM Controlled, but the coil is a MSI higher output and my engine will almost never run over 5K.

Replacing that module is a super pain in a van.

And suggestions?

Rich
 
USE of different distributor's , various HEI and aftermarket ignitions and coil combos react differently to having a resistor in the circuit,
I've had both good and less than good results, so I can't give you a firm, yes or no on the potential results
 
1993 is a TBI engine? Can you run 4-pin module with TBI?
Or are you carbureted?

About the HEI modul, i recently came across a Transpo Heavy Duty 4 pin module.
Copied from the specs: (of course some is the usual sales BS)

Features:
  • OE compatible intelligent micro chip matches vehicle specifications and conforms to emissions standards
  • Intelligent micro adjusting dwell time maintains accurate and consistent peak ignition
  • Transient protection on all pins eliminates high voltage backfeeding from Coil to ECU and electrical system
  • Control Board uses proprietary TRANSPO integrated electronics to improve signal clarity with high frequency filters, 4 layer processing chips provide fast and efficient signal processing
  • Designed to operate under a wide range of temperatures (from -40º to 125º C)
  • Common failure symptoms include engine nostart, the engine may be misfiring or running rough, and check Engine light illuminates
 
It is going into a 1993 Chevy Fuel Injected van converted to handle the 6 extra injectors.

Could not fine a HEI module Transpo Heavy Duty 4 pin module. But seems a few are now making higher performance parts that was not around the lat time I needed them, all were just standard parts....

If your interested in what I am doing check this out, (includes engine pictures and notes.)

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Rich
 
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