GM TBI on my 1970 360 duster

clair.davis said
MSMat,
Is there a way to check if the pickup is wired backwards? I'm running a LB distributor on my 340 (part of a MPI setup based on an AFI "kit"), and the tuning trouble I have FEELS like a spark problem, but I haven't fully ruled out fuel yet either. I'm pretty sure I wired everything properly, but between a house move and a new computer since I started the project, I'm having some issues backtracking through my notes. FWIW, I'm running a 7730 controller, tuning with TunerProRT and Moates' APU1 emulator.

Is this something I can check by forcing the ECM in to limp mode (short A&B on the ALDL) and putting a timing light on the damper?

Thanks,

Clair
Click to expand...

You've pretty much got it. Disconnect the B pin from the HEI and hold a timing light on it while you rev the engine. If the pick-up's wired backwards, the timing will retard as RPM comes up. If it's wired correctly, it'll hold the same timing throughout the rev range.