I have a firend who is thinking of swapping his 94 454 mag efi (bad block) for a new bobtail 383. What additional accessories will he need or should this just be a simple swap?
Thanks

The brackets from the 454 will not bolt onto the 383...he will need to find a donor SBC to provide all of the necessary brackets unless he buys a drop in. The exhaust and cooling system set up is the same as other SBC's and the parts are readily available.

This should be a decent replacement. A modern Vortec 383 matches or exceeds the Horsepower and Torque of most standard 454's with the advantage of less weight and better fuel economy. I see this done frequently here in South Florida with good results.

If he is getting a bobtail, then it will be complete and ready to drop in. It should be a straight forward swap. The only question is if the new small block is drive by wire. Other than that, no sweat.
Eddie

and if its a bravo boat he will need a sea water pump.

The exhaust on the SBC is about an inch narrower. This isn't an issue if he's through hub but if he has through hull exhaust the tips won't line up.

Options are either relocate the tips or some custom fitment of the exhaust.

Thanks, this was the kind of info I was looking for

if its manifolds and rubber hoses after the elbows they will flex enough to work

Sent you a PM. I have a 454efi with 109hrs that might be a better option for your buddy

That depends on the individual setup. The trident hose allows you to cheat a bit more too because it is more flexible.

However it gets far more tricky when you are dealing with captains call, etc.

I'm also not sure on the height of the exhaust between SBC and BBC. I started measuring things out to go the other way (SBC to BBC) and decided it wasn't worth it after a few things were going to have to be changed.

I considered the SBC to BBC my self and was ready to go until I found that the spread just about has to be 34" minimum. My twin SBC 255 Formula is set up at 32 1/2" and it's not worth re working the transom to do it. I guess it's doable with a custom fabricated exhaust but the maintenance headaches resulting from loosing an 1 1/2 would be unbearable.