On Holleys, the Primaries have Main Jets, along with addition Fuel being added thru the Power Circuit, when the Power Valve opens under load. Most Secondaries but not all, do away with the Power Valve Circuit, and therefore the Main Jets are larger from the get go.
Getting an Auto/Truck Carb calibrated for marine use, is just not changing Jets, and you are done, more differences are needed to provide the proper fuel delivery curve. I know a lot of Guys, and a few Gals, having tinkered with their cars/trucks, think it is no different with a Boat. A lot of them also think Distributors, Starters, Alternators, and other Parts are the same on a Marine Engine. I won't go on their Boats.
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