Don't forget to put a layer of thermal paste between the heatsink and the module. Just like the CPU on the desktop motherboard. Or between a power transistor and its heatsink. Many "rewritten" instructions omit that step.
bad gasoline? (not!)
- Thread starter JD1964
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Quality heat sink compound is a must... when i aquired a 2005 gmc scsb truck(4.3L/4L60E) almost 3yrs ago, i used the Dow Corning 340 compound(good to 350F) to replace the goop that was used between the factory ICM and the aluminum finned heatsink, worked like a charm, and to this day, no issues whatsoever from my ignition system.
You wont need much, so all you need is the 1oz contaner - https://www.amazon.com/dp/B00D0HVYHI/?tag=gbody-20
You wont need much, so all you need is the 1oz contaner - https://www.amazon.com/dp/B00D0HVYHI/?tag=gbody-20
It’s got heat sink compound. Between both the module and the factory aluminum heat sink, and between the factory aluminum heat sink and the added copper heat sink.
Luckily I do have a spare GM AC Delco module on hand. It’s used but at least I can give it a try to see if it makes a difference in the stumbled idle conditions.
Luckily I do have a spare GM AC Delco module on hand. It’s used but at least I can give it a try to see if it makes a difference in the stumbled idle conditions.
I changed the ignition module. It’s still doing the exact same thing. It starts off running good from a cold start. Then when it warms up really good, it starts acting up. Not right when it reaches operating temperature, but after it’s been running at operating temperature for 10-15 minutes. Then it starts acting up.
Changing the module was no love lost. It’s an easy thing to do. And I had a spare so no wasted money either.
When its at the point of acting up it also develops a valve train tap but it’s a deeper than the rocker arm I think. Maybe a lifter collapse? Next I will check the valve adjustment since that doesn’t cost anything.
Vacuum is good at idle 21 in Hg.
Changing the module was no love lost. It’s an easy thing to do. And I had a spare so no wasted money either.
When its at the point of acting up it also develops a valve train tap but it’s a deeper than the rocker arm I think. Maybe a lifter collapse? Next I will check the valve adjustment since that doesn’t cost anything.
Vacuum is good at idle 21 in Hg.
I would suggest before doing anything thats in depth with any engine , check fuel pressure and voltage at the HEI.
Let it idle and see what the readings are when it stumbles. That way, at least you can eliminate any fuel or spark issue before tearing down the block.
Sometimes a rubber vacuum line will expand and then fit loosely on the fitting. The hose may look good but will pull off easily. The vacuum leak would only affect idle.
Otherwise put a timing light on each plug lead while you idle and rev the engine. You are looking for "dropouts."
Otherwise put a timing light on each plug lead while you idle and rev the engine. You are looking for "dropouts."
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