Mercruiser out drive compatibility

[kenny nunez]

Do both drives power trim or just power tilt? Power tilt models used a setting pin and a mechanical lock on the drive. And power trim models used a hydraulic lock valve.
Power tilt drives will work on a power trim boat but a drive from a power trim boat will not stay down in reverse unless you switch the lock mechanism.

 

[Ghg]

Ok, so if I just use the lower unit of the outdrive from my original outdrive I’ll be all right? The gear ratio is determined by the upper unit of the outdrive correct?

 

[Scott06]

Ok that’s what I was getting at , assuming the original prop hit the correct wot rpm you will need a higher pitch prop to account for the higher gear reduction in the 4 cyl drive.

as an example I repowered my current boat.it originally had a 4.3 V6 with a 1.81 ratio drive. I upgraded to a 5.0 V8 that from the factory would have had a 1.62 ratio drive. I kept the 1.81 with the bigger engine went from a 19” to 21” pitch prop and it worked just fine. You will need to do the same and step up in pitch to make it work

Oh man I confused myself sorry to the OP and others if you are putting a 6 cyl drive on a 4 cyl engine then yes you need less pitch . I thought you had a 6 cyl engine and 4 cyl drive. …I’ll shut up now

 

[Bondo]

Ok, so if I just use the lower unit of the outdrive from my original outdrive I’ll be all right? The gear ratio is determined by the upper unit of the outdrive correct?

Ayuh,....... Correct,......

 

[Ghg]

Ok, thanks for all the good advice