Maximum Spark Retard

[keny]

Hi all, long time reader first post.

Table B5156 Maximum Spark Retard has got me a bit confused, does the value mean
amount of timing that can be reduced or where the timing can be reduced to.

eg: if you enter a value of 12 will the spark retard be limited to 12 deg from current timing or will timing not be allowed to be reduced passed 12 deg btdc.

Thanks

[joecar]

Hi keny,

my understanding:

Maximum Spark Retard: the maximum amount of relative timing that can be subtracted from the current absolute timing.
Minimum Spark Advance: the minimum amount of absolute timing.

i.e. Advance is absolute timing (this is how it is defined), and Retard is relative to Advance.

So in your example, it is -12° relative to current timing.

[keny]

Ok so a value of 12 in the table means up to 12 deg can subtracted from current timing
So a value of 0 would mean no timing can be subtracted from current timing

My tune has a value of -20 what does that mean if at 0 no timing can be subtracted?

I thought -20 may mean timing can not be retarded past 20 deg atdc
0 may mean timing can not be retarted past 0 deg
20 may mean timing can not be retarted past 20 deg btdc

[RonC]

Keny,

I have B5156 set to 8 deg and that is the lowest I have seen it retard down to, anytime. You might try a safe setting # and log to confirm.

Ron