how about Holley Tech Support?I’ve put some miles on the truck this week, and things could be better. There’s a major misfire I’m having trouble tracking down. First and second gear are ok, but higher gears, at higher rpms, it misses bad. I wrecked a couple of the old plug wires back when I swapped the head. So I made and installed new ones. No difference. Pulled the plugs, and they all looked good. Light grey/tan, no deposits, no soot. They only had maybe 5k on them. I decided to replace them anyway.
New vs old. Seems I’ve been running the wrong plugs the last few years. I figured this was my answer. Nope. Replaced the coil, as I had a new one on hand. Still no real change. It does seem to improve very slightly as I drive it, so I’m thinking maaaaaaaybe it’s an issue with the EFI, and it just has to learn? But it’s definitely an ignition misfire. I can see the AFR on the screen, and watch it drop from 13-14:1 down to 9:1 as rpms increase until it finally misses so bad it stops accelerating. If I push through, it’ll eventually smooth back out most of the time. If I downshift and get the rpms way up, it immediately stops and runs fine. I’ve got all the stuff to get rid of the ignition module and vacuum advance, and run the timing off the EFI, so I think that’s my next step. If that doesn’t help, I’m really lost as what to do next.