let's see your cold air pan/box to seal the carb to the hood

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I have a ugly home made one I can take a picture of next time I'm at shop.

Just a thought, do not think that a dual carb total cfm and a single carb will be the same.
On my little Camaro motor I run dual 1050's, but when I had the single, it ran best with a 1150.
The 1300 was way too much and it didn't like it.

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Here the airpan I made up for my cowl hood.

 

Here's mine.

 

Here are a couple more pic's. All the pan is some scrap alumium with a carb bell attached, and moroso airpan foam(supposedly fire proof). I don't have enough hood clearence for a filter so I just use the top, when I'm towing or storing the car.

 

Here's mine . I started with an original air cleaner for the base. it's made with aluminum & polished. Lid is 1/4" aluminum plate.

 

I got a killer one... just dont have the motor in right now to take a pic... will try to dig one up...

 

I had that pan sitting under a Harwood scoop on my old dragster. Filter may sit a little too deep in the pan so take that into consideration. I think that pan is at least 6" deep.