[Vwdiesel] Re: [Audi-VW-Diesels] White smoke means?

[Gary, Orlando]

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I believe timing is more pump specific, with a little input on
application.

Example: the late 70's/ early 80's Rabbits came with both a normal pump
or a "yellow dot" pump. The Yellow Dot's were timed to 1.15mm, where the
normal pumps were timed to 0.86mm.

I agree a specific engine needs to have all the fuel pumped in, or at a
certain amount of crank degrees.

Different pumps had different plunger diameters. A larger plunger
size(shorter stroke) will have pumped a set amount of fuel sooner than a
smaller diameter(longer stroke) plunger. If you were to average the fuel
delivery over crank degrees, the larger plunger pump would need to be
timed later. See my crude drawing...

Many others including myself have run their normal pumps at significant
advance settings. There was a "improved performance" setting for NA
pumps of 0.98mm for '81-'82. '83-'84 had a setting of 0.95mm standard.
I have tinkered with mine ad nauseum, and have always ended up setting
it at 0.92mm, essentially splitting all of the "normal" pump settings.

Just my $0.02

-Gary, Orlando



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On Wed, 2002-10-16 at 09:44, Nate Wall wrote:
> <<<Right now I'm timed near the Rabbit
> setting.  IIRC, white smoke means too much advance, correct?>>>
>
> Nope, that's an indication its retarded timing. (Also can be an indication of
> other problems, such as low compression, too.) Less time for the fuel to burn
> when retarded, so th white, unburned fuel (like when its cold out). So is the
> "Gutless" symptom you mention. I believe timing is motor, not pump, specific.
> Use a dial indicator and time to the Rabbit motor spec and see what happens.
> Fuel economy should increase too. Fuel economy and power increase w/
> advancing timing, up to a point, than pressures continue to increase w/ more
> advance, straining the engine. I think its risky to advance timing beyond the
> spec.
>
> Wow, 1.05 to 1.15 timing spec? Maybe it is pump specific? I thought the TDs
> had the most advanced spec, and thats at 1.00 MM. (Its because of the higher
> break pressure injectors take longer to open, so the timing is advanced to
> compensate for the slightly delayed opening on the TD).
>
> --Nate

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