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base / advance timing - TBI/TPI with distributor
I have been having a discussion with another gear head about how advance
timing is calcualated from the reference pulse generated in the
distributor.
Here is how I described it, and would like a reality check.
Pre LS1 small block chevy firing order is 1 8 4 3 6 5 7 2. Firing occurs on
90 deg. intervals.
Distributor is set for 0 deg (TDC) advance with the timing connector
unplugged.
Sequence
1) # 2 cyl comes upto TDC and a reference pulse is generated, the ecm
loads a count value into a timer register based upon current RPM and lookup
table value ( a lower value == more advance, higher value == less advance).
2) timer reaches 0 generates a timer interrupt, ecm issues a fire pulse to
the ign. module, #1 cyl. fires xx deg BTDC #1.
3) #1 comes upto TDC and another reference pulse is generated, timer is
reloaded for #8 firing event.
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