thru-transom exhaust

[79schiada]

On my drive swap and engine upgrade, I was going to upgrade the exhaust and go thru transom. I'll be running a 383 an probably using EMI thunder exhaust. If I ever put a big block in sometime down the road, am I going to have a hard time using the same holes in the transom, and is there something I can do now to make it happen easier later? The boat in question is a 21' Schiada RC.
Thanks:D

[CONCEPTMARINE]

The b/b chevy exhaust holes are about 1 1/2 inches wider than s/b. so the best thing to do is if you have the room is to drill for the b/b,EMI b/b are about 32 in. on center.

[79schiada]

Thanks for the info. I'll make sure that I can make it happen before I drill. If not, I guess I'll be stuck with a small block. Could be worse........no boat at all!

[spectras only]

Is your RC a V-drive ? If it is , the engine is far enough from the transom to use a softer exhaust hose that could allow some alignment to your existing holes . My 1972 Spectra V-drive had a BBC and the hoses were not lined up straight from the manifolds , because the stringers were somewhat in the way . They were going outwards at least an inch , yet I never had a leak with double clamping on both ends of the hose . I'd hesitate drilling other holes if the transom is in perfect shape .Other solution would be to machine an offset adapter to align the BB with your existing holes :idea: .

[79schiada]

I was just trying to plan for any future mods as far as engines go. I'm upgrading to a Bravo 1 from an old 260 drive.