Yes it is an IDI. Although both GMs and Fords have a Stanadyne DB2 IP, they have several different features, such as:
Ford: CCW rotation, throttle hookup on passenger side, round mounting flange
GM: CW rotation, throttle hookup on driver side, triangular mounting flange
and of course firing order differs between the two.
I have no way of timing a diesel correctly. I have a digital timing meter for a gasser, but not for a diesel, so by ear is the only way.
Of the factors that you mentioned, I know my fuel is causing me grief. It is the only reason I decided to adjust the timing. I have the GM Detriot Diesel FSM for both 6.2 and 6.5. I also have the Stanadyne DB2 IP Manual, although it highlights on (I believe) a Ford 6 cylinder version.
Interesting note about 3 degrees, dime width. From the setting mine was at for D2 (about 1/8" or on advance side), I have now advanced it about another 1/32" to 1/16" advanced to make it run the same for my dirty diesel. So approximately 3/16" advanced, or say 3 dimes. That would be about 9* advance. I cant find my manuals, but when I do, I'll find the stock timing setting and post back. I think it is about 1/8" advance.
I do appreciate all discussions and help.
I shouldn't have to worry about hard cold starts because (A) I rebuild this engine last year, approx 5000 miles ago and (B) I already did the manual glow plug switch mod. I've never had hard starts until I started mixing dirty diesel. I know I haven't mixed enough to find where my truck is happiest, but I hope to soon. I hate hard starting.
I adjusted the timing this morning. Not only base timing, but also timing advance curve. Took out the slop using the adjuster screw on the bottom of the advance cam lever. Then I adjusted the advance curve on the throttle shaft. I must say the seat of the pants dyno really likes the new setup. I'll drive it to work today to field test it some more, and when leaving work we will see how it starts cold.