This past May I swapped in a 350 into my '85 Z28 after it sat forever. When I fired it up it had hesitation and ran rich. After tuning the TPS, IAB, M/C and fixing the float I got my 30deg dwell, no hesitation and the exhaust smells alright. WOHOO! right? not yet. The motor seems to run pretty rough still.

I checked the timing at idle and its ~20deg retarded?? It does advance with vacuum and RPM, so its functioning somewhat. Initial timing is 4deg advanced.

Checked: (using Haynes' manual and an diag scanner)
intial timing 4deg advanced
Vacuum = 20"
Baro & Map in spec
TPS = 0.48V

Possible culprits?
still have the 305 ESC and knock sensor
180 deg thermostat

If I just disconnect the ESC will this disable it without affecting the rest of the ECMs operations? Any ideas?

 

Sounds to me like you have the static set to 4 degrees retarded; and it goes to 20 degrees advanced when you hook it back up. Which is about what it should do.

When looking at the timing mark on the damper with a timing light, advanced = toward the pass side of the 0 degree mark on teh stationary tab; retarded = toward the driver's side.

 

Its definetly ~20 degrees retarded when idling and 4 degrees initial advance. When I get a chance I'll pull the ESC and see what happens.

Oh the ECM does enter closed loop, dunno if this matters.