Spark timing, '747
rauscher at icst.com
rauscher at icst.com
Mon Jan 18 18:22:23 GMT 1999
In a previous post, Bruce mentioned:
>There is a spark adder, called main spark bias, which moves the
>entire table up or down in value. So lets say your at 0 degrees
>advance with a spark bias of 10 degrees. If you drop the spark
>bias to 0 then your initial timing of 0 becomes -10. There are >some engines
that are fussy about the initial timing, and spark
>bias.
>Generally I find alot of engines like 6d initial, a spark bias of 6.
>Now just to really foul things up/and/or confuse them there is a >cold spark
bias. Normally I have a fair amount there (15ish).
>Then with the above 16-20d BTDC idle timing.
>From what I know, for timing:
Initial advance. This is the physical position of the
distributor. Set this with timing light with bypass
disconnected.
Spark Adder (main spark bias). A location in the ECM mapping?
Anyone know where this is?
Cold spark bias. Again, mapping in the ECM?
This all pertains to the '747 ECM.
BobR.
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