D21 fuel smoking

D-21 engine injection pump (if that's what it is) shall be timed at 34 degrees BTDC. What are you timed at ??   If you think a D-21 is smoke free out the exhaust pipe, they are NOT. Valve lash needs to be adjusted to .017" COLD on intake and exhaust valves.

Edited by DrAllis - 07 Oct 2024 at 10:09pm

Hmmm, wonder if the pump shop used the series 2 fuel setting?  

Many shops don't understand how to assemble a DC pump properly, and therefore the timing mark ends up in the wrong spot. It will be difficult to time without taking the pump apart and correcting it. 

COLD starts do, in a way, indicate injection pump timing. Easy cold starting could mean retarded timing. Say, instead of 34 degrees BTDC you might be timed at 28 degrees BTDC and it would cold start wonderfully compared to 34 degrees BTDC. In the owners manual it even says for cold starts 50 degrees F or colder, the intake manifold heater will be REQUIRED to get the engine to start. Retarded timing will give poor performance and smoke as you increase engine RPM's, which is kind of what you are saying.  I'm not there, but an experienced trained ear could diagnose retarded timing in 30 seconds of listening to the engine running.

I am no where near as knowledgeable as Doc, but if I had excessive diesel smoke, the first thing I would check for is a restriction in the air intake system.

With a pump with no advance mechanism in it. Most of the early allis with pump advance, like later 180, 185, 190XT, all 200/210/220 the pump advance is actually used as a start retard on them. So it lets the engine be timed to 8-10 degrees less, for better starting, but the advance is all in by 1000 rpm. Messing around with the pullers with inline pumps, they start pretty good at 30*, but get up closer to 40* better get the ether. Advancing the timing slightly does help the grey smokey haze they'll have once it starts though. Many pumps have a cold engine advance, not really for initial starting, but immediately after firing up.