Date:         Sun, 18 Jan 2004 23:02:47 -0500
Reply-To:     "Daniel L. Katz" <katzd54@YAHOO.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         "Daniel L. Katz" <katzd54@YAHOO.COM>
Subject:      Re: 85 wbx miss at idle...update =)

while below link is a fine article about detonation, this is different
than classic pinging due to over-advanced timing, where, obviously, the
spark initiates combustion. slight pinging is not serious, and an engine
that has a slight ping, occasionally, has essentially optimum timing.
ideally the engine would be just on the verge of pinging under all
conditions. one might think the timing should be set at exactly 0 deg BTDC
under all conditions, but it takes time for the mixture to ignite and
really start burning, and so spark timing is advanced in order to provide
the most umph during power stroke. wbx timing immediately advances off
idle, and so worrrying about 5 deg one way or the other in terms of engine
damage is ridiculous; engine idle will speed up as timing is advanced from
stock digijet, then must be adjusted back to spec, then timing re-
adjusted, in an iterative process.

dlk

On Sun, 18 Jan 2004 22:36:57 -0400, Herr Wibo Fichten
<wibo.fichten@ROGERS.COM> wrote:

>Actually,  5ATDC is the stock setting, although it is true the list
>recommends 5-7 BTDC.
>
>The 1.9L's 5ATDC is quite an annomaly as it seems like all other boxer
>engines were set at various degrees BTDC.  Apparently this had something
to
>do with being able to get the machine into North America' emmission
>standards.
>
>In my experience, 5-7 BTDC makes the machine much more powerful driving,
at
>the expense of an unstable idle.  It is also my experience that setting it
>to 5 BTDC makes it quite foul at idle, you can smell the unburnt
>hydrocarbons, probably wouldn't pass smog tests (none in this
jurisdiction).
>Then again, I am no expert, just telling you what I know, or think I know.
>
>This all brings us to the question as to why would there be pinging when
set
>at 5ATDC, as cw says it is mostly due to timming too far advanced, not
>retarded. There are other causes too, a lean mixture doesn't help, so do
>check those hoses for leaks.
>
>A good article on the subject of pinging (engine knock), generally is here
>http://zhome.com/ZCMnL/PICS/detonation/detonation.html
>
>
>Fichten
>
>