Just got two 1996 mercruiser gen vi MPI's from Ebay.
Can one of them be programmed to fire a reverse rotation 502-415? Jim Rose

Is that motor batch fire or sequen. inj. I'm pretty sure it's batch fire, if thats the case no problem.

It is a stock 1996 mercruiser VST system. I have read that they are batch fired but that fact seems to bounce around this forum. I personally do NOT know how they fire. Additionally, I have read that the Mercruiser ECU is NOT reprogrammable, one can only extract diagnostic info from it. Therefor, if it is a complete 8 injector batch firing then the MPI doesn't care about rotation. The MPI simply "injects" all cylinders each revolution. (I say this but I don't know it !!)

Batch fire works by firing 1 side then the other

If this is true all you have to do is have a cam made the same specs., buy a reverse rotation dist gear and wire the dist clockwise 12756348. I have done this many times. Have any questions just ask.

Hallelujah. I have found someone with experience.
Heres the deal:
1- I am replacing inboard 340 mie, 20 yrs old.
2- they were counter rotating engines
3- I would like to go back with 502-415's
4- I currently own two counter-rotating borg-warner trannies
5- 1800runsnew and others have NEW 502 C/R long blocks available
6- Are you telling me that I DO NOT have to buy new trannies but simply buy C/R 502's, install the 502 MPI, and away I go????
Thanks

The hardest thing you have to do is have the cam ground. The last one I had done was by Lunati.

As long as your here;
What majkes the MPI fire? (signal from dist, sensor on crank or cam, or what?)

You just saved me $3000 on a trannie.
If you get to Biloxi, MS dinners on me at the Beau Rivage Casino !!
Jim Rose

Batch fire fires from the dist, which will still be turning the same direction.

Wait a minute.
On my C/R 454's the dist turns opposite. Additionally, if I buy a C/R 502, it will already have a cam, right?
On my 454's EVERYTHING turn opposite !!! even firing order !!
Will it still work?

Wait a minute again.
If your last post meant that the dist turns the same as the engine, I agree.
Sorry.