[whale]

GN stands for Grand National. It is a class under APBA it means Endurance Racing. The boats are 20 to 21 feet long and run either NA engines or bolwn engines. Kind of like nascar on water. My set up is in a 65 Plymouth 2dr post. It is what the company raced as a factory A990 or SS. I am not sure what size the venturis are I guess them to be 28, and if they are that would give approimately 1000 cfm per side and 2000cfm for the engine. These engines came with 2 770 cfm carbs on a cross ram intake. The bathtub was for a single for nascar, but it is what the boat racers used in this class with this intake set up just like mine. I am just trying to use it on my car. Headers are made by TTI they are 2 1/8 equal length with a 3" collector. It was 80 today and the car ran well.....hot idle was at 800 rpm at 12.5 to 13.9 AFR , cruise was 11.3 to 13.2. WOT 10.5 to 11.8......needs a little more work. It seems the change to F-4 E tubes helped a lot. By changing to the smaller chokes I hoped it would speed up the air flow. I can change back to the 37 chokes and see what happens.