Corsa Diverters for 5.7
 

I scored an exhaust system off a BBC that was in a Chaparral boat including the pneumatic exhaust diverters. Actually, I think these were made by Mercruiser so technically they are Slient Choice. The owner did some major upgrades and can't use the thru-hull any more. The manifolds and risers are in decent condition so I'll probably sell those in the spring. The diverters are in excellent condition including the pump and controls and tested out perfect. My Shabah has thru-hull exhaust but the y-tubes were left in place and capped off. Everyone loves the sound of the thru-hull except momma so you know what that means.

Based on the configuration of the diverters I expected they would work with either big block or small block. The risers from the big block look like standard height risers and I even have the y-tube which looks pretty standard. When I got into the install the lower diverter tube that marries up with the y-tubes is about 1.5 inches too long which bumps into the top of the y-tubes. Everything seems to align perfectly except the lower diverter tubes go too far down. These were almost free so I'm not worried about doing some modifications but I want to be sure it is actually necessary. Would the height distance between the riser exit and the top of the y-tube vary that much? If so would I be better off putting a spacer under the risers or just cut the ends off the diverter tubes or y-tubes? My concern about spacers is the diverter and y-tube might not align any more.

The part number for the diverters is 15786-C. Any experience with this system or advice is greatly appreciated!