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Discussion Starter · #1 · (Edited)
I tried static timing. Got under, got access to crankshaft pulley, marked 10° with paint, moved the 10° to under the pointer as precisely as possible, then measured the voltage from the second from the bottom wire to the distributor on the 4 wire harness, disconnected the power transistor, loosened the distributor, moved the distributor and saw the voltage jump from millivolts to 5 volts. Thought this should be it but then noticed that the voltage didn't just change once for the one of four slots on the inside of the optical encoder but jumped six times in the span of the distributor adjustment range. So, I changed the crankshaft pulley to TDC and reasoning that the six jumps to 5 volts corresponded to the 5 notches, +5,0.-5,-10,-15,-20°, I went from fully advanced to what I assumed was the start of -10°. Started it up and it didn't run well so I just adjusted by ear as seeing that crankshaft pulley 10° notch is difficult even with the upper brace removed. One thing I did notice when shifting the distributor while attempting to static time is that one 5 volt level was longer than the others. It was only later I thought that the long 5 volt level was a combination of the one of four optical encoder slots and one or two of the outer ring of 360° optical encoder slots. I also recall that counting the 5 volt levels I had ended up with a level that wasn't the long level but from TDC it wouldn't be but I may have counted from the wrong end. It would seem possible that if one wants to set the timing to 10°BTDC, then putting that slot under the pointer and looking for the long 5 volt level would get that timing but I wonder which side of the long 5 volt level, the start or finish turning counterclockwise? I'd go try it again but I'm getting some misfires and will change the O2 sensor and while the idle is a little rough it's tough to time accurately. Anyone ever try it this way with success?

Okay, looked at the hood and it says 20°BTDC. It had been running rough, I unbolted the injectors and re-positioned. Ran smoother but not great. Changed the rotor for one I had changed out some years ago and it runs much better so I checked the timing. It was around 20°. I didn't see much change moving the distributor and the TPS connector was opened. Then I read a post that full swing of the distributor will only be 6°. That would agree with what I was seeing. Getting to the store tomorrow for distributor cap and rotor. I thought the service manual said 8° +/- 2° for automatic and 12° +/- 2° for manual but I must be mis-remembering. Let's see, the engine looking at the crankshaft turns clockwise so the rotor should as well (ccw from the drivers side). Turning the distributor CCW would retard the spark. Then moving the distributor CW would advance timing, moving the encoder and distributor wire contacts toward the rotor, advancing the spark. Watching the mv to 5v level changes on the second to bottom wire of the 4 wire distributor plug, with the crankshaft pulley set at the 20°BTDC notch, when the long 5v level is observed, one might back off to before that level and move CW and find the low to high transition which one would think would be the triggering of the power transistor. One would think that would work as a static timing to 20°BTDC then the ECM would need to input minimal adjustments. Gotta try it one of these days but working alone, moving the crank, standing up, checking the position, up and down repeatedly to get it right... As it is, I ended up putting it just about where I remember the distributor had been relative to, and in the V and it's running well.
 
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