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Discussion Starter · #1 ·
I have a 74 Impala with a 400 Small block and a 2 barrel carb everyone tells me the car will have more power and get better mileage with a 4 barrel carb. I need someone that has done the swap and seen the results first hand to give me some advice on this
 

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mid 70s to mid 80s were the gas saver days and so they put smaller carbs on the big motors to use less gas. Edelbrock recommends a 650cfm carb I believe for that size motor and I doubt your 2 barrel moves that much air. A 4 barrel will also use more gas, I dont see how it would use less? Its the same as a 2 barrel, 2 barrels are used all the time but when you open the throttle all the way the other 2 open. So you would feel the most difference when you floor it.

Its a pretty easy swap. New intake, carb and maybe throttle linkages. If you want to go cheap there are tons of used aluminum intakes on craigslist and ebay and some carbs but I would rebuild them if they are used.
 

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Discussion Starter · #3 ·
People say that the 4 barrels have smaller primaries than a 2 barrel so if you keep your foot out of ityou use less gas
 

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1976 CAPRICE
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I have a 74 Impala with a 400 Small block and a 2 barrel carb everyone tells me the car will have more power and get better mileage with a 4 barrel carb. I need someone that has done the swap and seen the results first hand to give me some advice on this
its personnel preference too.... how's it run to you?.... does it have the power you want when you step on it?

2 barrels run fine.. but if you want that extra punch do the intake and carb swap... it's pretty easy
 

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Discussion Starter · #8 ·
its personnel preference too.... how's it run to you?.... does it have the power you want when you step on it?

2 barrels run fine.. but if you want that extra punch do the intake and carb swap... it's pretty easy
It runs great right now it just seems to use alot of gas, but if im gonna get more punch outta just a carb swap im all for it
 

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1976 CAPRICE
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yea my 74' impala had a 350... with a 4 barrel...stock intake...just got a Holley rebuilt quadrajet, updated the dist to a billet electronic,k&n air filter, and dual exhaust with the quiet flowmasters and it ran real nice....put your foot into it and it goes...:cool:
 

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i replaced a 350 with a rebuilt 400 in my 70 impala about 10 years ago, the 400 used less gas, seemed like i stayed off the gas, and 400s have a shit load of torque
 
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