I have a clean Holley Model 4150 List-8572 carb, it's a marine carb. I also have a newer Holley 90670 body, that's a 670 Truck Avenger body. It is nearly new and has stock annular primary boosters.
My goal is to create a hybrid efficient 670 4150 style carb for my $500 truck, which should see a lot of highway miles, so economy is important.

Can anyone explain any differences between a regular highway carb and a marine carb? I'm mostly concerned about metering. For example, are the marine carbs set up to be rich at high rpm because boat engines spend a lot of time there?

Any pointers will be appreciated.

I plan to use the stock jet sizes from the Truck 670 for the primaries and the Street 670 for the secondaries as the truck avenger uses a metering plate, not jets. I do most of my driving from 4000 - 7000 ft so will most likely be going down in jet sizes as I tune.

Thanks,
R.

The only differences that I know of on a marine carb is that the bowl vent tubes dump into the venturi and the throttle shafts are machined to not allow fuel to seep out of them in a flooding situation. Other than that, I believe they are the same as a regular carb.