85' bayliner 280dp new engine

I have a 1985 2850 bayliner Contessa command bridge. It has the original 280 outdrive that had the duoprop conversion complete in early 90's. Outdrive has only 380 original hours. The original 5.7 was blown due to overheat. I want to install a new vortec marine 5.7 for the extra push but keep the low hour outdrive.

My question is.... as there are limited early year vortex that you can purchase a 153 tooth one piece flywheel for is it possible to use a 290 14" bell housing on my 280 outdrive.. I do understand that it would have to have the 26/10 tooth shaft, I was just wondering if everything else would fit the same.

I'd just put in what was there before. You won't really notice any performance improvement with the Vortec. You're moving the same boat with the same props, so, you'll be going the same speed as before. OK OK, sure maybe you get up on plane a weeeensy bit faster, and maybe you get an extra knot or two at WOT on flat water.

One thing to keep in mine is that going from a 1985 to a later engine, Chevrolet changed the rear main seal from a 2 piece design (1985 & earlier) to a one piece design (1986 and later). So any of the Vortec engines (1996 and later) would have the one piece main seal. With this change, the flywheels also changed. So you'd have to find out if the Volvo coupler that you have can be used on the later style flywheel. It would probably be easiest to stick with the same design as original. The Vortec does give 25-30 more hp, and also the roller cam which is a plus for durability. Check Michigan Motorz they have many options for both new and re-manufactured engines.

I have a 1984 2850 Contessa. I put a Michigan Motorz vortec 350 in mine 2 years ago. I had the 280 outdrive with the duo prop upgrade just like you. Everything bolted up fine. I'm running B2 props. Runs like a champ. Good luck!