Duo Prop on VP 290 Outdrives

[octowood]

If I replace the lower unit on my VP 290 sterndrives with Duo Prop lower units what else would I have to
change on the sterndrives and what would I need my gear ratio to be if powered by 5.7L sbc
Thankss

 

[RicardoMarine]

The vertical shaft tapered roller bearing race must be re-shimmed when a different lower unit is installed.
No exceptions!
See OEM instructions for this "Negative Pre-load".

The ratio required for a 5.7L is 1.95:1, and the ratio change for this occurs in the lower unit ONlY.
Transmission remains the same.

Grear oil changes to GL-5.

You won't regret this change.

.

 

[octowood]

Rick, Thanks for the info. where is best place to purchase these and are the lower units
I am removing with ss props worth trying to sell to recover some funding.
thanks

 

[RicardoMarine]

Unless buying new, you're at the mercy of e-Bay or local Craigslist, etc.
If you can get the seller to pull the bearing carrier, it will expose the gears, and several bearing races to examine.
This gives a good tell tale sign of condition.

If your s/p lower is the correct 1.61:1, and a 280/290 style, it could be worth $700-800 or so.

NOTE:
Once out of the AQ series, the lower units will not interchange with your 290 style. So you'll be looking at the 280 Duo Prop, 290 Duo Prop, or the DP A, DP B, DP C, DP C1 etc.
The E exhaust outlet is for the diesel drive.
Also, when/if going with a C or later Duo Prop lower unit, the vertical shaft is shorter, so the coupler now becomes the long coupler.

Try to negotiate the prop hardware in with the deal..... (FWD prop spacer and nut, AFT prop spacer and cone nut w/ locking bolt).... this too is expenisve stuff.

.

 

[RicardoMarine]

I was looking on e-Bay this morning and came accross this 1.95:1 Duo Prop lower unit for sale.
Ad says NEW.
The image shown may not be the actual drive (he has several ratios available), so you'll want to have the seller show you the actual 1.95:1 drive. (you do not want the "E" exhaust outlet, IMO)

I'd want to make sure that the vertical shaft bearing race was included.... as it should be.

His price is not all that bad when you consider that these were $3,700 four/five years ago.

.