I was over at OSS and a question came up about using a 4 cylinder igniter on a 2 cylinder so i was prompted to map out the firing order / ignition sequence and how TDC/BDC and 1-4 coil and 2-3 coils firing relates to the igniter and it's pickup.
I worked it out based on a 4 cylinder firing order or 1-2-4-3 and a twin firing order where the cylinder are 180 out like a 1-2 pair.
First the timing for the 4 cylinder here. You will see the upper 4 traces represent cylinders 1-4 with TBC and BDC represented across the top. Compression strokes are represented by a thick RED arrow going up. Exhaust strokes are represented by a blue arrow going up.
Each spark pair has a common colored dashed circle.
Light blue is #1 , #4 both compression and lost spark
Orange is #2 #3 both compression and lost spark
IgnitionTiming_4Cyl.jpg
The coil that is firing that is shown on the 5th line down. The last line shows which igniter is firing the coils. The rear pickup is R and the front igniter is F (or left and right when you look at the ignition plate respectively).
Just block out the 3-4 cylinder and the 1-2 pair should be how a 180 degree in line 2 cylinder is.
P.S (EDITED ONCE ) if any of this is wrong let me know
I worked it out based on a 4 cylinder firing order or 1-2-4-3 and a twin firing order where the cylinder are 180 out like a 1-2 pair.
First the timing for the 4 cylinder here. You will see the upper 4 traces represent cylinders 1-4 with TBC and BDC represented across the top. Compression strokes are represented by a thick RED arrow going up. Exhaust strokes are represented by a blue arrow going up.
Each spark pair has a common colored dashed circle.
Light blue is #1 , #4 both compression and lost spark
Orange is #2 #3 both compression and lost spark
IgnitionTiming_4Cyl.jpg
The coil that is firing that is shown on the 5th line down. The last line shows which igniter is firing the coils. The rear pickup is R and the front igniter is F (or left and right when you look at the ignition plate respectively).
Just block out the 3-4 cylinder and the 1-2 pair should be how a 180 degree in line 2 cylinder is.
P.S (EDITED ONCE ) if any of this is wrong let me know
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