Replacing a VP 270/80 utdrive counter rotation with a VP 290 DP?
 

I got this crazy idea to replace my old VP 270 (or 280, I don’t recall) with a VP 290 duoprop. Primary reason for doing this is; a) I could not locate a VP spline’’d 29P counter rotation prop, b) control of the boat around the docks is sketchy at best (yea, I am also to blame here) and, c) I put a 550hp engine in the boat and it is busting up the exiting outdrive (bending gear shafts, breaking shear pins, etc.. I was able to pick up a VP 290 DP from the lower all the way up to what looks like it attaches to the flywheel (unfortunately no prop or cone).

My question is, what is involved in swapping the 270/80 out and swapping the 290 in?

- does the 290 bolt up nicely?
- does the transom need to be redone?
- I already have hydraulic steering, will that swap in relatively easily
- hydraulics for the trim appear to have come with the new unit (not sure how this is controlled currently)
- the outdrive came with this big thing about half the size of a beach ball that looks like it connects to the flywheel, will that need to be changed and if so, does the engine need to be pulled to do this?
- i’m not running exhaust through the outdrive, that goes straight out the back via 4” pipes.

I’m certainly not versed in this enough that I would take the job on, this is why we have professionals, I was more or less curious about the amount of effort (hrs) this will likely take to swap in.

Thanks in advance for your insights.

I have actually done that exact swap and it was on a circa 1969 boat as well. I was after the power trim transom assembly and not directly after the dual prop although that is all confined to the lower unit so it could be swapped at any time. i got the transom assembly off a mid 80's Bayliner that had one of those funky DOHC 4cyl's in it so i knew the gear ratio would be wrong and luckily the upper gear section was backwards compatible with the older mid so after some mixing and matching i came up with a 290 mid/lower mated to a 270 upper mated to a 290 transom. From my experience nearly everything was a direct swap. Come to think of it i may have used a VP 285but i think they all interchange from that family

Hey Scott. The 290's shields is bigger. It's actually the biggest shield they make and well fit over the cutout for an OMC stringer drive without transom work so it will cover the old hole. Funny the second Monza I did ended up with a Volvo 290. Your hydro steering will work. You may have to come up with another aluminum piece that bolts to the top of the drive and connects it to the hydraulic ram but there is a pretty good chance the old one will fit. No matter what you will have to pull the motor. You will not get a 290 transom shield in a 280’s place without doing it. There is no other way. Bellhousing should be the same. I would go with the shortest of the two so the motors sits as far back as possible.
Summer is coming bud. That boat belongs in the water.


http://www.resurrectionmarine.com/0d254a40.jpg

Forgot to add duo prop props cost more then outdrives.

WIth VP duoprops I have yet to figure out how to choose which prop to get beyond the metal used. In the SS option they have 2 types one for straight splines and one for spiral - I have the straight. The next question is which configuration, F2 thru F9. I am guessing that F2 has a lower pitch and F9 has a higher pitch? If this is true, with 500hp I would think I probably want the highest pitch? (F9) It sure would be nice to better understand this before purchasing one of these beasts where a return policy may not be applicable.

Thanks!