258 power loss
88 YJ, 258(maybe 30K on rebuilt long block), MC2100, "TR" ignition with HEI module.
Loss of power during accelleration or when the gears shift(auto trans), my air/fuel gauge reads WAY too lean(when power is lost) but reads rich when cruising and at idle. The gauge also fluctuates from time to time, rich to way lean back to rich to slightly lean...etc.
What I've done:
Checked for vacuum leaks...over and over again...repaired as necessary. Set timing to 9-10*, gapped plugs to .035, higher grade gas, pulled distributor/cleaned/replaced. timed again...and again. checked curve...no change in timing from idle(700rpm)til about 1300rpm then jumps up til i cant see it, this occurs progressively until about 2500rpm or so. thats with ported vac connected...w/o vac connected, same thing but it jumps up about 4* and stops...thats the mechanical advance. I drove with and w/o vac advance connected, not much change. I've adjusted the diaphram on the distributor in and out...doesn't seem to help much.
I'm not going to blame the carb yet since the same thing happened when the weber was on there. From what I have read, mech advance is supposed to kick in from idle until about 1200 rpm, then vac advance takes over and should not bring timing above 35*. I've read, researched, asked you guys but still I'm missing something.
Your thoughts and suggestions are welcome...