Swapping SB's for BB's in a 272
 

So I am hoping I can get some good answers on here. I have what many have told me is a very rare set up in my '88 272 SR1. Currently running twin 320EFI's on Bravo 1 drives. (anyone else have a pair of these?) I am up in the air as to which route to go either built small blocks such as 383 strokers potentially using factory EFI or just to step up twin big blocks. I am no stranger to BB's having a Baja 272 with single 502. No doubt in my mind would I have much more torque with the BB's but the boat has no problem getting out of the water as it is.

I guess my biggest question I am looking for the answer to is will the BB's fit with the current configuration? My engine hatch lift is squeezed between the SB's with little clearance. Obviously the drives are where they are. Maybe someone could give me some measurements of a 272 equipped with BB's to see if the drives are even far enough apart.

Most SBC's are set up at 32~33" on center...BBC's need a minimum of 34". If yours are at 32 or 33" you are in for a major transom re-do to get 34" to clear the Big Blocks.

One thing to consider is 6.0~6.2 LS motors. They will go 32" on center no problem and if you can scare up the brackets to do it from a doner boat you can get very serious power from them in a light package.

The Vortec 355~383 motors get to 400+ horsepower and torque real quick...lot of bang for the buck.

Are your 320 EFI's tired? My '86 272 with those motors on Alpha SS drives would do 75.

Used to be a 272 local with punched 383's and ran 70 mph,

Yeah the spacing is what I was worried about. The 320's are doing alright... One is running a little flat but this is only my second season with the boat. Last year was only able to best 60 spinning 4700 RPM's full gas and 6 people. Currently running 23P props and may play there. Those 320's I hear should run up to about 5500 RPM's

Funny you mention LS motors though. Have been doing a little research on the LS3 / L92 motors. Maybe even go crazy with an LS7 or something. Doesn't look like it would be too bad to marinize these motors. Especially if more and more people are doing them.

Those 320's will spin 5500 and beyond. Find someone that can tune that EFI which is sort of "cave man" by todays standards.You're looking for an old school guy that remembers what it took to make them sing. If they have never had a valve job in their history they a probably due. Two good sets of stainless exhaust would be a good investment also.

Motors already have a set of EMI manifolds on them and with looking to go the LS route down the road I will be saving pennies for that. My biggest issue with the 320's is finding someone that knows what they are. I usually get the blank stare when I tell someone it has factory EFI motors from '88. If anyone out there knows someone in the northeast I would appreciate the help!

Here's a thread on an install of 6.2 liter/430 hp Ilmor LS engines into an SR-1 Formula:

Ilmor LS conversion

Is that boat originally from the Albany, NY area? I may know that boat since it was brand new. If so it did much time up on Lake George, I have a boat with the same 320 efi's and am looking for parts motors. If you are looking to sell all the fuel injection parts let me know. Scott 518 210 2030

I am from the northeast, call me 518 210-2030

Mercury's 383 stroker motor's were designed to replace 7.4L/8.1L. Factory warranty and support. Plug and play. I used the 357 version to replace a 7.4L in a Sea Ray with a Bravo 1 and it used the same prop and only lost 100 RPM. Used less fuel though. You can build your own, buy a something like the Summit one but I have to say Merc did thier homework on the cam profile as this thing makes the torque and horsepower to replace a big block Chevy.