Ok guys,

MEFI 3 BBC

What would happen if the injector batch firing was reversed from the attached picture. In other words instead of cylinder 1 Green, Cylinder 3 Blue, Cylinder 5 Blue, Cylinder 7 Green it was reversed and Cylinder 1 was Blue, Cylinder 3 was Green, Cylinder 5 was Green, and Cylinder 7 was Blue.

And the same for Cylinders 2,4,6,8 Green, Blue, Blue, Green reversed.

‘Thanks

Nothing, it really doesn't matter. Each injector is fired once in a 4-stroke combustion cycle. Because it is fired into the intake manifold before the intake valve, it's only being drawn into the cylinder on the intake stroke anyway.

Agree, nothing would happen
To note if the harness was from a L29 then the batch firing is different. L29 fires 1,3,5,7 / 2,4,6,8
the MPI uses 1,4,6,7 / 2,3,5,8

I know this was already answered but I will also elaborate/share THIS: since batch fire is 4 and 4, only one of those four is remotely close firing near a optimum valve opening event thats why it makes no difference which cylinder they are on. When I first set up my dyno I went as far as running batches swapped and batches down each side on their own which made no difference at all in power.I DID find for some reason Mercruiser double fires the injectors in a 500efi in the programming (every revolution) and 454/502s are single fired (every 4 stroke revolution). When I switched to double fire on mpi stuff that was single fired, it evened up the afrs slightly closer (I have 10 o2s on my dyno). IF you do your own mefi programming and elect to switch to double fire, dont forget to account for 2 sets of dead bands/latency in the injectors pw, Smitty

Very interesting. Thanks Smitty.