high octane spark table help

[tom70]

can anyone explain the spark table on bin file? sorry but i don't understand it. why are there negative numbers in table?

[steveo]

without actually looking at the bin, there could be several reasons for negative numbers in a spark table:

- the XDF is incorrect

- the engine actually is calibrated with spark occurring after top dead center in that region. it's not unheard of

- the spark table is not the only thing controlling final spark output. the negative values are combined with other values or formulas to achieve a positive final spark advance

[tom70]

I have a 12212156 bin file. What would be correct xdf file?

[Fast355]

without actually looking at the bin, there could be several reasons for negative numbers in a spark table:

- the XDF is incorrect

- the engine actually is calibrated with spark occurring after top dead center in that region. it's not unheard of

- the spark table is not the only thing controlling final spark output. the negative values are combined with other values or formulas to achieve a positive final spark advance

The numbers truly are negative at WOT and low rpm so a heavy truck can get rolling without detonation.

[tom70]

I'm using engine in a 72 chevelle. this was closest bin file I could get to work with my xdf file 12202088.
Is there a better xdf file for 12212156 bin?

[Pulse_GTO]

Try this XDF.

[tom70]

I will try that. Thank you

[tom70]

thank you very much. worked perfect!