So I'm back after 10 days...
Tuning that IP was not easy. I suspect it has been fiddled with before since I found signs that someone's been in there before me. Pulling the EDS solenoid revealed a shim plate that was upside down and had the locating pin mashed. I've never had that solenoid off, so it wasn't me who did it. When I got the IP, the idle speed was set ~1100RPM on the mechanical governor, so things are starting to make more sense!
My attempt at simply reducing the "Max-Load" setting (2f) was completely ineffective. If I reduced fuel, I started to lose the ability to idle. If I adjusted the idle fuel screw (2b) to compensate, I wound up with smoking at idle again. Round and round and round I'd go, always winding back up at the same point. Smoke at idle and heavy smoke under acceleration or load.
Then I got the bright idea to check timing. According to the crank pointer, I was right at 15˚ ATDC which is what the engine calls for. I decided to advance the timing a bit to see if it eliminated the "grey smoke" issue I was having at idle. It most decidedly did not. Smoke went from a grey haze to a thick black coal-smoke. If I adjusted the fuelling to even try to reduce the smoke, the engine would barely idle and wouldn't restart without some throttle.
Since that made things worse, I went back the other way and eventually wound up with the IP in the fully "retarded" stop of its adjustment range. Without touching the fuel stops, this not only ended the hard start issue, but also greatly reduced the smoke at idle.
With more fiddling with 2f and 2b, I managed to dial it in just about perfect. 0 smoke at idle, 0 smoke when running unless under WOT conditions and even then it's a mild haze, not the rolling coal it was doing before.
The best part is that I was able to do the final tuning and tweaking with the ALDA, which never seemed to have any effect at all previously.
The final thing worth mentioning is that the overflow valve I had installed definitely had an impact on the idle fuelling adjustment. In the past I had issues with hard starting when cold and nailing. I'd always assumed it was due to air in the fuel lines and installed one of Greazzer's performance modded OFV's from the 617's. It helped to an extent and was left in place. With all my tuning, I decided to try an original style "drilled orifice" OFV instead of the spring-regulated one from the 617 and it had a marked effect on the idle smoke.
Once tuned, there is ZERO smoke at idle, something I never thought my car would do. I knew it consumed oil from the turbo, which has now been rebuilt. I figured some of that idle haze was due to oil consumption. Apparently not. It is obvious that the oil in the sump has a fair bit of fuel dilution going on though. With the gross overfuelling happening with the way it was, I'm not surprised. It also explains why the oil consumption would increase rapidly the more miles the change accumulated.
The only thing left concerning me is why the timing was off, despite being "properly timed". I can only imagine that the pointer itself is incorrect. I'm now at 16˚ATDC according to the pointer. If it were off by 1˚ then that would explain a few things, although I'd still have expected the car to run better than it did with the timing being off by only 1˚.
Who knows, it's tuned properly now. Engine is quieter, smoother, and no more smoke and the reek it brings along! I swear that every repair turns into some sort of saga with that car...
