Volvo Out Drives Good Or Bad???

[ROBERT PARKER]

I HAVE A 26 FT SLEEK CRAFT I JUST PICKED UP AND I WOULD LIKE TO PUT A 540 BBC I HAVE IN THE BOAT. IT CAME WITH A 350 SBC AND THE 290 VOVLO OUT DRIVE. IVE BEEN TOLD TO HAVE THE SHAFT IN THE LOWER END HEATED (HARDEND) and i should be ok. IT IS THE SINGLE PROP. I WOULD LIKE TO GET THE DULPROP LOWER END BUT AM I WAISTING MY $ ON THIS OUT DRIVE???? ALSO IS IT A BIG DEAL WITH CHANGING FROM SMALL BLOCK TO BIG BLOCK? ONE MORE THANG WHATS UP WITH RUNNING DRY exhaust manifolds. DO I HAVE TO RUN A WET SYSTEM???

[2850 Bounty]

Originally Posted by ROBERT PARKER

I HAVE A 26 FT SLEEK CRAFT I JUST PICKED UP AND I WOULD LIKE TO PUT A 540 BBC I HAVE IN THE BOAT. IT CAME WITH A 350 SBC AND THE 290 VOVLO OUT DRIVE. IVE BEEN TOLD TO HAVE THE SHAFT IN THE LOWER END HEATED (HARDEND) and i should be ok. IT IS THE SINGLE PROP. I WOULD LIKE TO GET THE DULPROP LOWER END BUT AM I WAISTING MY $ ON THIS OUT DRIVE???? ALSO IS IT A BIG DEAL WITH CHANGING FROM SMALL BLOCK TO BIG BLOCK? ONE MORE THANG WHATS UP WITH RUNNING DRY exhaust manifolds. DO I HAVE TO RUN A WET SYSTEM???

First.... you'll be pleasantly surprised at the performance with the Duo Prop. Many times it will perform as though you added 100 HP with no other changes.
Maybe consider staying with a good strong and much lighter weight SBC (383 for example) and installing the Duo Prop lower unit.
Some critical shimming is required, but the AQ series DP will bolt on to your existing Intermediate housing.
The Flywheel Cover is same for BB or SB.
You do need the 153 tooth flywheel though.

No... you do not necessarily need to stay with a Thru the Drive exhaust (if I understand your question) .... it will, however, need to remain a WET system in that hull unless you do not enclose the engine..... and I doubt if you want that.

You cannot beat this drive for reliability and strength and ease of service.

Install NEW Primary Drive Shaft bearings! Period!

[jflongwell]

I have a 350 w/DP and it gets good fuel economy. One problem with the DP is cavitation erosion on the small prop means repairing (welding) it about every three years or so.

[2850 Bounty]

I know exactly what you are talking about re cavitation burn/erosion.
I am running twin 270 HP 5.7Ls with the 290 DP's, B-5's.
You just live with it, keep them protected with an epoxy paint, or go to the SS props, of which I'm not willing to do quite yet.
Shaft damage X's 2 would be expensive. I do have impact coverage, but would prefer to not use it.

[KnottyBuoyz]

Originally Posted by jflongwell

I have a 350 w/DP and it gets good fuel economy. One problem with the DP is cavitation erosion on the small prop means repairing (welding) it about every three years or so.

I think it's against some unwritten rule to use "fuel economy" in sentences discussing boats!

As per cavitation erosion, I'm getting it on the leading edges of the large prop. '87 AQ271A with the AQ290DP running B4's. There's no erosion on the small prop which I got with the B5's. Strange. One piece of advice on the DP's, don't defer maintenance. If it says replace bellows every two yrs (or whatever) do it! I didn't, paid the mechanic later ($$$). Other than that, bulletproof drives IMHO.

[2850 Bounty]

Speaking of advice, for those of us who work on these drives have no doubt at one time or another removed a corroded-in-place propeller from a Duo Prop shaft.
It almost always involved cutting an otherwise good propeller from the shaft. $$$$$. It's too bad to see this.

So, Lake, River or Salt use..... pull your props routinely (at least once per season) and clean and grease your splines!