School Me on a Small block to big block swap with same drive
 

Just for arguments sake lets not wory about what drive is used (Alph or Bravo)
I am contemplating a swap from small block 350 to BBC . If I swap engines will the drives transom asymbly need to be moved at all or is it just a direct swap of engines? Would the big block need to be set up any different motor mount wise to align with the existing drive? What would be the proceedure for engine placement and alignment.
For instance, If my small block is mounted at the top of the stringers, would the big block have to be lowered in to the bilge any. How do You go about setting up for a BBC swap with an existing drive set up?.... Hal

It's a direct swap...only issue you might have is exhaust and normal stuff like fuel lines and wiring.

As said above...everything is the same. If you are currently using the stock 9 pin plug then that will be the same as well. Exhaust will be the same as long as it is stock and not using any spacers under the risers. The only thing you will need to watch is if your risers are 3" or 4" outlets, you will need the same in the BB risers.

Alignment procedure is the same as well as where your mounts are located in relation to the hull. It is pretty much drop in and go.

The only setup change that will need to be made is prop size. A little research here may give you an idea of what is needed.

watch the alignment so you arent pulling the motors back out to change couplers

make sure engine has bravo couplers on fly wheels or you will be pulling motor back out after you jump out of your seat when running at speed and coupler fails.

good info here.... for arguements sake... with the A1 currently in my 21' mirage handle a BBC? and for how long assuming I'm not jumping the prop in and out?

Fixx
 

if your going from a sb to a bb everything is wider,through hull? 3'' wider,motor mounts? wider,y pipe wider.if you have a engine cover that wraps around the engine, measure it.

engine is under the rear sunmat like a bigger offshore boat.

Small block is narrower than a BB

That's a tough question because there are so many variables - like what kind of shape your Alpha is in right now. I know a guy with and original 1987 Sea Ray 22' Pachanga with the dreaded 454/330 / Alpha drive still intact. Of course he drives it like a little old lady.

It's more than jumping waves that kill an Alpha drive. Hard starts, incorrect drive lubricant, heavy boat, water in the drive, and many, many other problems can spell doom for your Alpha with big block power in front of it. Are you sure you really want to do this? BTW: It's the kiss of death on resale value too.