Time for me to replace my 7.4 330 manifolds so I purchased 496 take off mainfolds. I noticed that the water hoses to my stock risers may have to be plumbed with a "T" fitting to work with the 496's. Any other suggestions for this plumbing? Can I replace (or plug) the thermostate housing so that those hoses are eliminated? Thanks for any advice!

Get a Mercruiser manual on your 330 7.4 mpi engine and study the raw water system plumbing flows and make sure when you use the Merc 496 manifolds you plumb the system to work just like your original system as far a flow and direction is concerned.

Best Regards,
Ray @ Raylar

Thanks for the advice. I did some more research and found that EMI has a diagram of how they install their system on engines with two hoses (1 to the manifold and 1 to the riser). They recommend that you use a "Y" fitting that routes both hoses to the bottom of the manifold...makes sense and keeps water flowing to the manifold and riser.

My 496 takeoffs came with a Y fitting one has a checkball, the other goes right into the manifold, which goes where?

anybody??