1979 el camino 305...carb question?

diffrence is horse and usage of gas. go with a quadrajet if you want to save on gas. there are good ones out there

I would go with the edelbrock 500 cfm because the 600 cfm is putting more gas in the motor than the 500 and since you don't need much horsepower the 500 cfm will work perfect.I'm not sure the difference between the 1405 and 1406. I hope I was some help.

Tim.. The cfm of a carb has NOTHING to do with how much gas it puts into the engine

The cfm is how much air it flows in cube feet per min.

A 600 is your best all around size

The 1405 is a man. choke 600cfm carb, where if you want it to have a choke you have to hook a cable to it and mount cable inside the car and pull/push cable to open and close the choke.

The 1406 is an elec. choke 600 cfm carb, where you just hook a pos and neg wire onto the choke and it opens and closes the choke based on engine temp

The 1406 is also jetted alittle leaner (I think 2%) meaning the jets are smaller, or metering rods are bigger. This is what changes how much fuel goes into the engine. The jet and rod size. Leaner jetting will get better mileage unless you need more fuel like on performance engines