Carburetor size

70Duster340 said
After watching the video on sizing a carburetor, I was wondering if using the carb that I have (Holley 670 Street Avenger) would be too much carb for the engine. It's going on a 1971 340, rebuilt with. 030 over forged pistons and Edelbrock aluminum heads. Using the calculator, the carb should be around 487 cfm. This will be used as a street car. It's going in a 1970 Duster.
If I left out any pertinent information, I apologize.

You left out a ton of information, but that doesn’t matter because the first thing to inform you about is the video and calculators are dumb and wrong on so many levels I’m not going to waste 10 pages of cyberspace listing and explaining the how, why and what should be. The calcs are moronic at the mildest and nicest description.

The calculators are telling you what the engine can consume. What you’ll find is if you put a 500 cfm carb on top, (13 cfm more than the calculators say) is that the car will be under powered, slow and constantly in the secondary side just to get moving.

If there is any doubt, I point to 2 sources of actual real information in history and current use as we speak.

1: Chrysler’s 340 engine first used the small primary TQ. Then moved to the larger primary TQ. This had an actual flow over 760 cfm. On a STOCK 340!

2: Speak with the drag racers here and they tell you that for Dudley, “More carb the merry.” (Within reason of the build and the duties it drives under.)

Use what ya got for now.