Ok, I went through this exact same thing.  First it drove me nuts that
setting the timing to the specifications causes the engine to run poor with
lack of power.  For weeks I thought I was doing something wrong, then
finally I just accepted that my engine (20K miles on a rebuilt) likes the
engine to be at a few degrees BTDC more then the manual calls.

With the Aux Air Regulator, there seems to be a delay of about one second
from the time you squeeze the hose and the time you hear the engine drop.
The drop is quite suttle and you can best hear it when the engine is stone
cold.  The Aux. Air Regulator gradually closes the air flow when it get's
hot.  I believe it is heated by current going to the censor and not the
actual temperature of the engine (although the engine temp does have an
effect as it is bolted to the engine).

So a slightly warm engine will have less air-flow from the Aux. Air
Regulator then a stone cold engine/regulator.  Try the test again first
thing in the morning just after starting the engine.

Good luck,

Paul Borghese

----- Original Message -----
From: "Jay L Snyder" <Jay.L.Snyder@usa.dupont.com>
Newsgroups: groupstudy.vanagon
Sent: Tuesday, May 01, 2001 8:40 AM
Subject: Digijet Timing Marks

> Last night I scratched a TDC mark straight across to the back flange
> (closest to the block) and measured the distance from there to the 5 ATDC
> notch.  I then painted a new mark (5 BTDC) the same distance on the other
> side of the new TDC scratch mark. I set the timing at 5BTDC and adjusted
> the idle.  (I was running at about 2 or 3  BTDC).  I must say, it runs
> mucho better than 5 ATDC.  I took it out for a test drive and could not
get
> it to ping.  I do have premium gas in the tank.  I did not disconnect the
> vacuum lines when setting the timing and had the idle stabilizer by-passed
> as the Bentley shows.
> I also tried starting cold with the idle stabilizer by-passed to see if
> the Aux. air regulator was working--it was.  With the stabilizer
connected,
> it is hard to detect any change in rpm by squeezing it the way the Bentley
> says to do.
>
>                                                         Jay  '85 Westy
>