Devo45, I think you're right because I believe the ECU controls the timing and the old "turn the distributor" adjustment procedure is for the 4.2 only. Furthermore, the ECU controls mixture also, so you're out of luck there too (sorry!). I guess carbon build-up could be a factor considering the age and if it wasn't maintained real well, but I don't know what else to suggest.
Not to walk on the thread, but Jeff--you should be able to still adjust timing as usual even with the Weber, I did it just this afternoon to try and squeeze a little more advance. As long as the vacuum advance hose is disconnected and plugged, and the light is attached to the #1 plug wire, you should be good to go. Make sure that the vacuum for the vacuum advance is coming from the stock location (that gold-tone thing that protrudes from the intake manifold near the EGR) and not the side of the carb--the carb outlet is ported vacuum for pre-1983 (I believe, whenever they changed the distributors).
Currently an '86 CJ-7 and a '77 CJ-7 Golden Eagle---#4 and 5 following a '01 Sahara, '90 Sahara, and '85 CJ-7....