Spark advance tuning made simple and quick?

[Bruce Plecan]

> Whasa KPA ? ;-)

A term used in proper ecm maps and tables <G>..

> I think (from reading ECM and otherwise) that optimal spark timing has
less
> to do with knock threshold and much to do with power output.

Oh, so you did read the Tuning.doc.......

>Obviously if
> you get the best power under a knock condition then you still want to back
> off, but a 383 and 377 (popular article I read) performed best at 36
> degrees.

Sounds like Iron heads, and or large chambers, eh?
Never seen best power with knock, border line, or right on the edge but once
it starts HP drops, from what I've seen.
Lets also remember (165/730), that there is no IAT timing correction, so
rather a little to low then high for evryday drivers.

> Take a look at the "dyno version" ARAP for the '165. See what they
> came up with as "optimal" for the TPI 350. I've taken the approach of
> increasing WOT advance 1 degree per track visit from 30 to 36 (or beyond)
> until the car starts to lose E.T.

With rare exception, going past 36, and your needing to add fuel for
cooling, and more at compression ignition the you might want to beleive.
Also, can make for erratic performance.

>  for part throttle its a different
> game.I'm thinking. You must either maintain load and allow RPM to slowly
> increase, or maintain RPM and allow load to change... thru several
> iterations you can find the knock areas... alternatively you can drive
> around normally while constantly recording and run the recordings thru a
> utility to spit out the 'attention' zones (or just manually find them).

Not what I've found,
I use TPSv for trying to optimise timing fuel for cruise, and then the least
amount as you transisition to WOT.

I'll
> probably stick to ARAP with high-delta-LV8 (producing knock) based spark
> tweaks and WOT advance tweaks based on E.T. result.  So far, on the BFG
> drags, I have not had to manage the torque at launch, but I plan on
dropping
> launch zone spark if it comes to it.

> I better start keeping some secrets - the ears of (the local racers) MAFB
> are on the list now ;-)  of coarse I could be making all this up ;-))

As long as you post in public, the lil guys will be reveiwing what ya have
to say <g>
Bruce
>
>
> ----- Original Message -----
> From: Walter Sherwin <wsherwin at home.com>
> To: <gmecm at diy-efi.org>
> Sent: Friday, September 29, 2000 8:23 PM
> Subject: Re: Spark advance tuning made simple and quick?
>
>
> > Sounds like something that would be of interest to both the GMECM and
DIY
> > crowds.  Why not maybe paraphrase things in a short E-Mail to the
list(s),
> > and then later as time permits develop your website and let us know
where
> > its located when done.  New/different/bizarre ideas are oft the fodder
of
> > what has not as of yet been conceived.............
> >
> > Walt.
> >
> >
> > > Gentlemen, I have an idea that may save tons of time when tuning spark
> > > advance. In general, I have a very simple way of manually adjusting
> spark
> > > advance a known amount on the fly while driving. That way, you could
set
> > the
> > > entire SA table to say 25 below 60 KPa and say 5 above 60. Then, you
> could
> > > drive at known RPMs and MAPs and just manually dial up the SA while
> > listening
> > > or watching for knock counts on a scantool. Once you hear or witness
> > knock,
> > > just write down where on the RPM vs. MAP map it occurred and how much
> > advance
> > > you had cranked in and how much you backed out. Then, its just a
matter
> of
> > > reburning the chip one time with the results of the run. If there is
any
> > > interest in this procedure, I'll write it up in a website with digital
> > photos.
> >
>
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> >
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