I just pulled the intake manifold off of my Hardin Marine 5.7L and noticed the new intake manifold gasket set I have doesn't have the rear intake passage block plates that the motor came with. The little rectangular shaped tin piece that covers the last rear ports. Do I need them? I was thinking that they were probably there to help warm the engine? I do run a thermostat. And being this is a jet boat, I also have a gate valve limiting the water flow to the motor. Do I need them?
05-07-2011, 10:55 PM
They're not there to warm the engine, they are to keep the manifold from rotting away. If you don't boat in salt water I don't see any issue leaving them out, my SBC jet just has a set of normal gaskets in it, haven't had any problems.
05-09-2011, 07:30 PM
Really? Why would blocking the rear passages on the intake keep it from rotting? Im not doubting you, just interested in why. No I don't boat in salt water, just midwest river muck. I would have bet it was to help warm the engine.