Bbc 509cid, 9.7 comp, roller cam,230/236 @050", 112lsa. Dry section of the riser is now approx 15" longer than in normal riser, 6" taller + 9"longer. Is It possible to use the silent choice diverters? I could limit the water flow going thru the exhaust if needed. The line attached to inner transom assembly shows the transom line.

Considering to buy extender bung for the h2o sensor.

You could run any regular performance exhaust with diverters with that cam. You basically have a 500efi cam or similar.

Ok, so I could leave the diverters like they are and not modify those to reverse type diverter, and still be ok?

500efis are known for small amounts of reversion at idle effecting the back two cylinders.

Atleast my engines showed signs of it when the top ends were rebuilt.

With silent choice?

Merc 500 efi cam, 230/236, 114lsa. 5° overlap @050". My cam, Same duration but 112lsa, 9° overlap @050".

how would you guys reduce the water flow out of the riser? how big holes would be enough to keep things cool? i know this is been done thousand times but cannot find any threads about this subject. my cam has almost twice the overlap @ 050" compared that 500efi cam, dont want damage a fresh build engine.

Just a thought- take the risers to a skilled tig welder and have him extend the inner 3" pipe through the transom. That's what I did when I got tired of worrying about reversion.

This is what we did when we were concerned…run dry exhaust.