HEI Conversion Question and Holley 2280 Lingering Issue
Update.
Decided to check the simple stuff and thought I had figured out the issue. I made a twisted pair cable out of an old distributor pickup cable end and two female insulated connectors. Installed that and moved the coil wire away from the new jumper between the module and distributor. Drove the vehicle about two blocks and immediately felt the stumbling return. Turned around went back to the house. This time I swapped the female disconnects on the HEI module. Drove about 80 miles. Truck ran great. Thought I had figured it out. However, it had no power at idle and would die if the steering wheel was turned in a parking lot. Figured I would probably need to go back through the carb settings and ignition timing since I had fiddled with the module wiring. First thing I noticed was that I could not get the idle speed to drop below around 850RPM even with the idle screw completely out. That concerned me, so I threw a timing light on it, and it was advanced around 28 degrees. So, I figured I would need to reset everything back factory including base timing and carb idle settings.
After doing all this I had 12 degrees BTC @ 750RPM. I then reset the idle mixture using the factory propane assist method. Readjusted the accelerator pump linkage to zero clearance and the mechanical power valve to the new idle throttle stop position. Then reset the high idle speed, which took a lot of turns to get to 1500RPM, which should have set off my spidey senses, but so far everything was working well.
Jumped in the truck for a test run. No power whatsoever. The more throttle I gave it, the more sluggish it ran. I then reconnected my timing light and did some checks to see how the advance curve was. Well, it was the opposite of advance, as soon as it came off idle, the timing would retard fairly dramatically. At a steady throttle position, as engine vacuum would build I did get vacuum advance to pull a bit of timing, but the engine was steadily loosing timing as RPM increased.
At this point, I swapped the leads back just to see if the timing responded similarly. Well, it didn't, granted the base idle with the leads swapped was around 300RPM and timing was about 18 degrees ATC so, barely running. I did managed to grab the throttle linkage and get it to rev up and the advance did work in the correct direction.
I'm leaning to having a bad ignition module. The attached pic is the diagram I used when I originally did the conversion years ago. It ran fine like this for years until the original distributor ate itself and I replaced it. It was actually running pretty well even with the pickup grinding into the reluctor wheel.
Update.
Decided to check the simple stuff and thought I had figured out the issue. I made a twisted pair cable out of an old distributor pickup cable end and two female insulated connectors. Installed that and moved the coil wire away from the new jumper between the module and distributor. Drove the vehicle about two blocks and immediately felt the stumbling return. Turned around went back to the house. This time I swapped the female disconnects on the HEI module. Drove about 80 miles. Truck ran great. Thought I had figured it out. However, it had no power at idle and would die if the steering wheel was turned in a parking lot. Figured I would probably need to go back through the carb settings and ignition timing since I had fiddled with the module wiring. First thing I noticed was that I could not get the idle speed to drop below around 850RPM even with the idle screw completely out. That concerned me, so I threw a timing light on it, and it was advanced around 28 degrees. So, I figured I would need to reset everything back factory including base timing and carb idle settings.
After doing all this I had 12 degrees BTC @ 750RPM. I then reset the idle mixture using the factory propane assist method. Readjusted the accelerator pump linkage to zero clearance and the mechanical power valve to the new idle throttle stop position. Then reset the high idle speed, which took a lot of turns to get to 1500RPM, which should have set off my spidey senses, but so far everything was working well.
Jumped in the truck for a test run. No power whatsoever. The more throttle I gave it, the more sluggish it ran. I then reconnected my timing light and did some checks to see how the advance curve was. Well, it was the opposite of advance, as soon as it came off idle, the timing would retard fairly dramatically. At a steady throttle position, as engine vacuum would build I did get vacuum advance to pull a bit of timing, but the engine was steadily loosing timing as RPM increased.
At this point, I swapped the leads back just to see if the timing responded similarly. Well, it didn't, granted the base idle with the leads swapped was around 300RPM and timing was about 18 degrees ATC so, barely running. I did managed to grab the throttle linkage and get it to rev up and the advance did work in the correct direction.
I'm leaning to having a bad ignition module. The attached pic is the diagram I used when I originally did the conversion years ago. It ran fine like this for years until the original distributor ate itself and I replaced it. It was actually running pretty well even with the pickup grinding into the reluctor wheel.