You hear of a "Six Pack" and "Tri-Duce" (carb setup with three two barrel carburetors) ...

Wouldn't 4x2 barrels or 2 four barrels be better?

  • Welcome to Motor Vehicle Maintenance & Repair! I don't understand what you're asking exactly; please edit your post to use proper grammar and to add some more detail. Thanks!
    – Cullub
    Jun 11, 2019 at 15:07
  • There are engines that have had 1 barrel per cylinder, and of course fun to tune...
    – Solar Mike
    Jun 12, 2019 at 4:52
  • Didn't one model of the Chevy Corvair have four one-barrel carbs? I had one back in the day, and that's what I seem to remember. A female-dog to tune, too.
    – BillDOe
    Jun 17, 2019 at 20:19
  • (most) Four barrel carbs don't send one barrel to each cylinder. They normally operate on two barrels unless you are floor-boarding it. Look at your intake manifold. It's not dividing the carb per cylinder.
    – John Lord
    Jun 21, 2019 at 15:30

1 Answer 1


A 3x2 setup tends to run on just the middle carb most of the time and the throttle on the outer two is only opened in high rpm operation. There isn't a need to match the number of barrels to the number of cylinders when the outer carbs are essentially just there to allow a lot more air in at full throttle and high rpm.

Some race cars do use 4x2 setups with one carb per cylinder but they are designed to run at High rpm all the time.

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    And the center carb is the only one with a choke, much simpler. And 4 barrels will have progressive linkage ( 2 bbl to 4 bbl) so they need to be synced together for best performance. And in the good old days when I had them , the 2 bbl were less complicated and expensive than 4 bbl. Jun 11, 2019 at 16:31
  • This is exactly right. Done correctly, it can be the best of both worlds ... plenty of top end with a "somewhat" decent mileage down on the bottom end. This also allows for better torque down low as well, then as the other four barrels of the carb setup opens up, you get that top end HP you're looking for with such a setup. You'll find these (usually) on the larger engines, such as the 440ci Chrysler BB or 427ci BBC. Great setup when done correctly! Jun 11, 2019 at 19:54
  • There are factory cars with 2x4 carbs also. Dodge hemi engines had them and big block wedge engines and a few chevys. Tri power setups could be progressive as you stated, but there were models with full on triples. You can set them up any way you wish.
    – Moab
    Jun 11, 2019 at 23:46

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