2 barrel , 4 barrel, whose got the answer?
going from a 2bbl to a 4bbl will net you more power but likely at the expense of fuel mileage.
As long as the go pedal isn’t pressed hard or often…… LOL
I seriously disagree! Big time. Here’s why;
A 600 cfm 4bbl carb is what I used in my ‘79-360/904/2.76 drivetrain in my Magnum w/235/60/15’s which returned 20 mpg. The mods to the car were as followed.
A OEM ‘‘72 trap door air cleaner w/K&N filter.
600 cfm Federal-Mougal (Edelbrock) electric choke emissions carb
OEM spreadbore 4bbl. intake
MP chrome box
(I later added a MSD6 - good for more mileage at slow speeds/rpms)
Junkyard distributor from a truck
Dual exhaust off of the exhaust manifolds @ 2-1/4 w/an H pipe.
Due to the laws of the time, a visual inspection was done yearly (N.Y.) which required the car to have catalytic converter(s), so twin high flow cars were used after the H pipe into Dynomax turbo mufflers exiting at the bumper.
As 318WR said, tunning the set up is key to how it runs, so, the car was subject to constant tuning between the distributor timing and jetting of the carb. Also pay attention to the pump shot amount. Use only as much as the engine needs. Jet it on the lean side. (Lean for winter. It’ll richer up slightly for the summer. Air molecule expansion, and contraction due to the temperatures.)
The laws at the time said the car must be running for the test on dyno rollers while have a tail pipe sniffer attached. The car passed for a late 80’s F.I. standard. There was zero lack of power, drivability and was used on an easy dozen trips from Long Island New York to Snellville Georgia, Richmond & Lynchburg Virgina.
Routinely, 20mpg was the average.
YRMV, the gear ratio and tire size are a big play in the mileage search.
Could I have done better? Probably so if I decide to use headers, some, deletion of the A/C, mechanical fan, better intake manifold, etc. I decided to use the KISS method for this daily driver as it was my only car. I seen no sense in dumping extra money into it with minor advances in power and mileage. I was using it daily as my only car so messing with it further did ‘t really seem worthy to me.
Keeping your foot out of it will net good mileage results.
Sometimes, depending on the 2bbl, the 4bbl can have smaller primaries.