If you advance the timing too far, the engine won't run correctly. However, it won't harm the diesel like it will the gasser. It is a recommended by most diesel shops and TDP to advance the timing on the 6.2L. I think the factory sets it back a little to quiet it down a bit. Advancing the timing will make the engine a lot more peppy.
Here is an excerpt from a question asked on TDP just like yours:
"I have a question about diesel engine pre-detonation. I Have always know that ignition pre-detonation in a gasoline engine was always considered bad; potential piston, valve, and spark plug damage. What about for a Diesel engine? You alway hear diesel engines, and they all seem to display the typical pre-detonation rattle. Should the fuel injection pump be set at the point where this detonation just begins or this advancing the fuel timing too much?
I have a 82 GMC, K2500 pickup, with a remanufactured 6.2L, J model in it. I got it with a rebuilt Stanadyne, DB2 mechanical pump. I noticed that when I align the pump timing marks with the factory marks, no engine rattle is noticeable. But, if I advance the pump approximately 1/8" toward drivers side, the rattle is very distinct, but engine definitely has improved performance. Sorry for being so long-winded!
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Posts: 4 | From: Jacksonville, Fl | Registered: Dec 2002 | IP: Logged
CleviteKid
Moderator
posted 01-23-2003 10:19 PM
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There is no such thing as pre-detonation in a diesel. What you are hearing are structural vibrations induced by extremely rapid pressure rise rates. Your engine can take it, if you like the improved performance.
Dr. Lee "
Advancing the timing makes a big difference in "seat of the pants" feel! I've actually got mine advanced about 1/4" on my '81, but I wouldn't go that far on the first try. You can keep moving it until you feel the performance and noise is suffering, then back off. It's hard to explain, but you can tell when the timing has been advanced too much.
Casey