Do I need a block off plate on my manifolds?

Question

Can any one tell me if I need a block off plate between my manifold and riser if I do not have a heat exchanger system?

I have a 1973 Mercruiser 888 w/302ci.

I bought them used and had them cleaned and checked and they had a plate in them.

Answer 1

Yep!!

The 888 exhaust cooling runs (flows) from the back to the front, back to the thermostat house and then runs to the elbows risers together with the warm engine water.

If the elbows are not blocked (exept the air bleed hole) to much water will run straight up out the elbows and not cooling the exhaust manifolds sufficient.

Frank