Typically advancing the fuel delivery of a diesel will increase combustion pressure which results in an increased load on pistons, rods, bearings... "pinging".

At the same time it generally will increase economy, lower exhaust temperature at the expense of a higher NOx emission. However, the HC will decrease with earlier injection. Smoke may increase at peak torque rpm and decrease at idle.

The specific time of delivery is also based on the pop pressure of the injectors as well as fuel viscosity. So, the drip method of setting the injection timing is meaningless if the pop pressure is not within spec.

I really wouldn't worry about it too much if it runs good and the timing chain and tensioner/rail is in good shape. I read too many storys about new chains letting loose. MB allows for quite a bit of enlongation by the use of offset woodruff keys to restore the valve timing.

BTW, I'd like to advance the cam to lower the peak torque rpm. I wonder how many degrees is too far???

Been reading through this thread, and it reminded me of something that happened many years ago.

Then, I had a Toyota Celica 2000GT. with a chain-driven DOHC engine....

During the usual servicing I did normally monthly, I noticed the Ignition timing retarded over two months tests. I re-set and basically forgot about it...

Then I had a rattling/knocking, just like pinging noise. A few days later, the lower crank chain sprocket broke....

The central bolt holding the crank pulley and crank-sprocket had worked loose and the sprocket wore the key in the crank and eventually broke, leading to 3 bent valves and a couple of broken guides...

The point to the story, was that when checking the timing, it was varying wildly over a short space of time due to the wear accumulating at the crank sprocket/Woodruff key in the crank....

I hear quite a few 'new' engines here in the UK with cam-belts suffer from this very problem too...

Definately worth checking that central bolt in the crank that it is fully tight, Just in case.....

__________________
http://i190.photobucket.com/albums/z...0TDnoplate.jpg

Alastair AKA H.C.II South Wales, U.K. based member

W123, 1985 300TD Wagon, 256K,
-Most recent M.B. purchase, Cost-a-plenty, Gulps BioDiesel extravagantly, and I love it like an old dog.

W114, 1975 280E Custard Yellow,
-Great above decks needs chassis welding--Really will do it this year....

So far so good...!

I readjusted the timing pump today - if you look back at post 16 you will see how far I first adjusted it. This morning I moved it back to right in between these two marks and the car runs better - no pinging and knocking, and no smoking.

Thanks for all the advice and helpful suggestions. I have come to the conclusion that worrying too much about factory specs and procedures can, at times, be detrimental to the process of getting a 30 year-old car with more than a quarter-million miles on it running well. I would always start from those numbers, etc., but one has to do some trial-and-error testing along the way. Plus, the process of measuring is fraught with error - the best we (home mechanic) can do is average and approximate, although I would argue that even with the best tools, measurement is "close" at best.

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE

I believe the RIV tool will get it "perfect" every time.

__________________
http://superturbodiesel.com/images/sig.04.10.jpg
1995 E420 Schwarz
1995 E300 Weiss
#1987 300D Sturmmachine
#1991 300D Nearly Perfect
#1994 E320 Cabriolet
#1995 E320 Touring
#1985 300D Sedan
OBK #42

I don't think the RIV tool will work for my application - NA '78 300D??? Correct?

ryan

__________________
RG Newell

1984 300D
1972 250
1986 560SL
1991 300CE