Thanks for the post! I am running CMI e top headers and 871 with chiller on BBC jet drive. What is the best routing of water for cooling? Schematic or picture would be awesome but a quick run down would help too. Types of fittings used in and out of the block. Thanks for your replies!

How are you pulling the water into the engine now ? are you running a T stat and water pump or cross over

From the pump through a gate valve directly into the block where a water pump would be.

is the water pressurized while sitting still............so you're not running a circ pump but a cross over where the water pump would bolt ?

Pressure comes from pump bowl. If engine is running there is pressure. Currently no crossover. Looking for recommendations.

what size is the hose from the pump to the block, is there enough volume to split it and take a -10 or -12 to the intercooler

4 sure.

It's been a while but in the last jet drive boat we had; we used -12 from the pump to a regulator then oil cooler then a split to two -10s to water pump mounts (or the block ). In your case, you might want coolest water at IC first so my thoughts would be pump to regulator, to IC to oil cooler to block and no smaller than -10. From there you will need to figure out exhaust and a dump if necessary.

The regulator really is important as the bowl pressure in jet drives is generally way too high for typical cooling system design ... you can get by with a gate valve by restricting flow but it just isn't the best approach even though many/most jet boats were built that way.

Not sure if you have tried performanceboats.com or River Dave's Place or SoCal Jet Boats but I am sure you can find pics of other's setups there.

Good Luck!