Real pump timing numbers a secret?

[BC Clark]

I cannot seem to locate what the actual timing in degrees should be for a 6.2 Diesel. I have aquired a Snap-on MT-1480 and can measure the actual injector pump timing, but it seems to be some kind of dark secret. Not even my factory manual lists it. I like the one post that says advance it until it sounds like a Ford and then back off.
The vehicle is a 1988 GMC Jimmy with the 6.2 and 700R-4. I have recently swapped the intake with a non-EGR manifold and would like to fine tune the injection pump timing as well. It currently reads about .5 to 1 degree ADC at 600 rpm and 3.5 to 4 degrees BTC at 1500 rpm. I notice that the pump has been moved slightly to the advanced side of the mark.

Thanks!

[britannic]

With a turbo, I was using 2.6* BTDC @ 1300rpm. For low NOx (emmissions compliance) use TDC @ 1400rpm, however you won't like the low power output :( .
The non-turbo military's timing figures:

6.2L: 4* BTDC @ 1300rpm upto 1989 inclusive
6.2L: 5* BTDC @ 1300rpm 1990 onward
6.5L: 5* BTDC @ 1300rpm

[BC Clark]

Thanks! Looks like I'm pretty close to where I should be. Was kinda hoping it would be off as I don't seem to be getting the milage I should, around the 18mpg mark. Haven't completed a full tank since I did the manifold swap but it did seem to feel better. Need to check the rear end ratios as they may have been swapped. Seems to have a pretty good launch. No tach so I haven't for been able to really tell if the torque converter is locking either. It feels like it is.

Thanks again.

[britannic]

Note: if your timing chain has any appreciable wear causing retarded cam timing, your fuel mileage will be impacted negatively.