034 EFI
Orin Eman
orin at drizzle.com
Tue Dec 4 23:22:25 EST 2001
>
> On 5 Dec 2001, at 0:14, JShadzi at aol.com wrote:
> >
> > << I was thinking about this. It means that I would have to use the
> > 4ksq flywheel, and not the 200tq one I am planning using, right?
> > Unless I had the 4kq/NF/NG timing pins put in the 200tq. So far
> > the machine shops I've talked to don't even want to deal with the
> > existing timing pins, I can imagine their reponse to some custom
> > work.>>
> >
> > NO, the NG/Nf do not use pins, its all from the hall sender.
>
> Very cool. I think it's coming back to me now. I remember thinking
> the MC system was strange with the flywheel timing, back when I
> drove a Coupe GT!
You have to go back and read the SAE papers to find out why they
used the flywheel teeth for ignition timing. Quite simply,
there is too much jitter in the signal at the distributor to get
accurately repeatable timing. From one of the papers:
"...the signal from the camshaft. This would however lead to
a significant loss of accuracy because in the case, results would
be affected by mechanical backlash between the crankshaft, camshaft
and distributor shaft".
Now no doubt Javad is going to say that using the distributor fired
ignition works fine - and it does, but it isn't optimal. You have to
set the timing such a little retarded such that the jitter in the
ignition signal doesn't cause knock. Ah, but the knock sensor catches
that you say. Yes, but in general, when the knock sensor kicks in,
you lose - they use large amounts of retard and slowly advance back
to the programmed timing. With the timing map on my 5k set to just
avoid knock, it pulls strongly to redline. With the the stock timing
tables and the knock sensor handling things, it has that running into
molasses feeling around 4800 RPM.
> So, I'll continue with the plans for using the 200tq flywheel, except
> the concern for the pins presence is greatly dimished. I can get it
> turned now. (that takes care one of them, I still need a 5kcstq
> resurfaced, keeping those pins) I already have the clutch (and no
> 200tq), and I want the 240mm disc and lighter flywheel.
BTW, the PIN that matters is on the engine side of the flywheel.
Those on the clutch side are for VW diagnostic tools that are capable
of reading timing from them.
Orin.
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