Was it a Vic Jr ? Single plane is a very generic statement.

yes, "old" is scary

Victor, how can old be scary.

Just double checked, Victor Jr

Good info there. It looks like the dual plane is better for accelerating, but the single plane may make better power up top where a boat can spend most of its time. Genericaly speaking, of course.

The dual plane made the same peak HP as the single at the same rpm, but made way more torque for an additional 1000 rpm.

In this application with mild 502 build and the 454-O, would you go 4150 flange or 4500 with adapter?

with a car with a fan on front of engine you have airflow past the engine. the airgap will have some effect there. boat engine not so much.

That pretty much answers my question. I have the crossover blocked off and a splash shield underneath so I'll call that good. I'm sure every bit of distance you can get from the heat is good but no need to pay $ for something I don't need. I do mostly stop and go type of boating with very little wide open so I'll leave the dual plane and try a 1" spacer.

the air gap manifold does not make more power because airflow past the engine