747 Timing Calc

[rr]

Amazing isn't it?

BobR.

Brent wrote:

> I'm having trouble figuring out how the 7747 calculates timing.  This stock
> bin is for a '91 Chevy C2500, 350, auto, 3.73.
> http://www.paonline.com/WildKat/arjt000.bin
>
> Lets run the engine at 3200RPM, PE mode, 100KPA, 75d C coolant temp.  I'll
> assume there is no knock retard.  I used WinBin to find the values.
>
> According to the 747 timing doc there are 15 or so parameters that are added
> together to result in total timing.
>
> 1  Timing Table   + 21.09
> 2  Slope               + 0       (starts at 3600rpm)
> 3  Coolant Comp  + 20.4
> 4  EGR adv       + 0
> 5  PE adv        + 2.11
> 6  Aldl adv      + 0       (or should this be 8.09?)
> 7  Startup adv   + 0
> 8  Hiway adv     + 0
> 9  Warm Bias     - 9.84
> 10 Cold Bias     - 20.4
> 11 Dissy Initial - 0
> 12 test for max adv
> 13 Burst knock   - 0
> 14 Knock         - 0
> 15 Latency Correction
>
> Total = 13.36 degrees @ WOT
>
> Does this truck really only want 13.36 degrees of advance @ WOT?  I think
> I'm missing something.  What did I leave out?
>
> Regards,
> Brent
>
> Timing doc I am referring to:
> http://www.diy-efi.org/gmecm/ecm_info/1227747/projects/747_ignition/spk747.t
> xt
>
>

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