Ability to reverse the firing order on demand?

[stobl]

The important point being that as another poster indicated, if the center of the gap is exactly at TDC, the timing calculation will be the same regardless of which way the engine is turning.

This is why I'm thinking placing the sensor exactly between cylinders 3 and 1 TDC would be ideal. since there is 60* between their TDCs, placing it halfway would make it 30* BTDC going both directions. Forward would be Trigger-30*-#1TDC. Reverse would be Trigger-30*-#3TDC. This is all assuming a 36-1 wheel on the crank, which wouldn't be hard to do at all since the pulley for the distributor would be removed and provide an easy mount for it.

Also, if the sensor is placed that way, all coils would need to be swapped when going in reverse. #3 would be the first to fire after the gap, and #1 would be last.
Forward T-1-6-4-2-5-3-T-1-6-4-2-5-3
Reverse: T-3-5-2-4-6-1-T-3-5-2-4-6-1

[billr]

I'm not sure what you mean by "putting the sensor between #1 and 3". The sensor can be anywhere convenient, as long as the missing-tooth gap is centered on the sensor at TDC or BDC. Nothing is going to avoid switch the coils or there outputs (a dizzy).

[stobl]

I'm not sure what you mean by "putting the sensor between #1 and 3". The sensor can be anywhere convenient, as long as the missing-tooth gap is centered on the sensor at TDC or BDC. Nothing is going to avoid switch the coils or there outputs (a dizzy).

putting the sensor and gap alignment at 30* BTDC for cylinder #1 fixes the issue of adjusting the trigger offset when running the engine in reverse (It will also be 30* BTDC for cylinder #3 when run in reverse, as the TDC's are 60* apart) If you put it at TDC for #1, although that will be a 0* offset when running forward, it would be 60* offset when running in reverse. The few time's i've set it up, i've mated up the sensor and gap at 20-60* BTDC as suggested by the manual. Matching them up at 30* just eliminates another issue that comes with trying to run in reverse, that's all.

[racingmini_mtl]

I'm not sure what you mean by "putting the sensor between #1 and 3". The sensor can be anywhere convenient, as long as the missing-tooth gap is centered on the sensor at TDC or BDC. Nothing is going to avoid switch the coils or there outputs (a dizzy).

putting the sensor and gap alignment at 30* BTDC for cylinder #1 fixes the issue of adjusting the trigger offset when running the engine in reverse (It will also be 30* BTDC for cylinder #3 when run in reverse, as the TDC's are 60* apart) If you put it at TDC for #1, although that will be a 0* offset when running forward, it would be 60* offset when running in reverse. The few time's i've set it up, i've mated up the sensor and gap at 20-60* BTDC as suggested by the manual. Matching them up at 30* just eliminates another issue that comes with trying to run in reverse, that's all.

That's because you see the reverse order as starting with cylinder 3. You should look at it as still starting from cylinder 1 and being 1-3-5-2-4-6. That way, you have fewer cylinders that need their ignition output shifted and it keeps the logic of always using cylinder 1 as the timing reference.

Jean