This past fall I purchased a 1974 Plymouth Duster 360 4-speed that was pretty much all original except it had a 1971 340 in it. The engine was already broke, so I pulled it out & set it in the garage and sent the car off to storage. Upon further inspection of the engine I noticed it had a Holley 4777-2 650 cfm double pumper carburetor. The more I thought about thing the more it made sense to try out one of those Holley 750 cfm HP main bodies on it and putting it on the 440 in the Coronet. The upsides of this main body are stunning good looks, slightly better flow capacity then a standard Holley 4779 750 cfm double pumper, and down-leg boosters instead of the original straight leg booster arrangement on the 650 cfm carb.
I'm hoping that there will be a performance gain when I swap it onto the car in place of the current Holley Street Avenger 770 cfm vacuum secondary carburetor.
I ordered the main body in dichromate finish to match the rest of my current carburetor. $137.35 shipped was the price for it brand new off eBay.
The main body retrofit kit includes non-stick metering block gaskets, non-stick fuel bowl gaskets, main body gasket, fuel bowl screw gaskets, and brass 72/84 jets. The accelerator pump discharge nozzles are both .031".
I'm hoping once properly set-up & tuned it'll make more power in the mid to top end power range without losing any low end and most importantly I can even get it properly set-up and fully tuned correctly.
The 1-11/16" throttle blades with a 750 cfm venturi size should also keep it ultra responsive at any throttle position / RPM for use on the street.
Turns my current Holley 4777 650 cfm double pumper mechanical secondary carburetor with straight leg boosters:
Into this Holley 750 4150 HP carburetor with down leg boosters:
