7747 spark control questions.

[Squash]

Wait, my brain just went numb.  Too many numbers.  Table says 20, Bias says 4 and dist is set to
4, total timing measured with a light is 16.

Squash

--- Shannen Durphey <shannen at grolen.com> wrote:
> Here's an example of exactly what I meant.  ANTZ8364, 89 3/4 ton
> w/454.  Base timing 4deg BTDC, base timing value in ECM, 4 deg.  That
> way the timing values in the table reflect timing at the engine.
> BTW, I placed antz8364.bin in incoming.
> Complete specs:
> ANTZ8364  1988 3500, RVCK, 454, 4SPDMAN, 3.42/3.73 REAR GEAR, 7747ECM
> Shannen
> 
> Programmer wrote:
> > 
> > >>Does the bias not reflect what the distributor initial timing should be
> > set
> > >at?<<
> > >
> > >All the timing decals I've seen are "0" EST bypassed.
> > >
> > >>Why would you have a value like this unless it was just for something like
> > >ALDL output?<<
> > >
> > >I don't recall even seeing a spark value on a scan tool for a 7747 truck
> > >app. Tech 1 maybe ?
> > >
> > >>> You could just add 10 degrees to the timing tables and set the
> > >distributor at 0.  No need for subtraction in the timing table<<
> > >
> > >Well---that's how I thought it was.
> > >
> > >What is the raw value for the 50kpa at 600rpm?
> > 
> > Oops...hit the enter key <g>.
> > 
> > Just checked a 1989 SWB Chevy with a 5.7L auto 7747 equipped.
> > Base timing is "0" BTC with the EST disconnected.
> > 30 kpa @ 1000 rpm (cold) measured timing is 43 BTDC.
> > 34 kpa @ 800 rpm (cool) measured timing is 38 BTDC.
> > --Got interrupted when some freight showed up--
> > 32 kpa @600 rpm (70C temp) measured timing is 22 BTDC.
> > 
> > And no--I did not use the diagnostic mode on the scanner which bumps up
> > the timing. TC's tables appear to be bang on...Winbin's you need to subtract
> > the bias value.
> > 
> > Lyndon.
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