7747 spark control questions.

[Shannen Durphey]

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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