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What is a 6 pack in the hotrodding world? Does it improve performance of my engine?

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A six pack usually refers to the Chrysler (Mopar) carburetor setup which is three-two barrel carbs on an intake. You'll most often hear of it as a 440 Six Pack, the 440 referring to the Big Block Mopar engine displacing 440 cubic inches. Here is an image of such a setup:

enter image description here

The interesting thing about these is they are setup sequentially, where the main 2-barrel carb will be used at first, then when the throttle is down enough, you'll get the other two carbs to open allowing for a large rush of air/fuel mixture.

This setup up can improve performance of the engine, with one caveat: only if the engine can utilize the increase in air flow. You can put as large of a carburetor on your engine as you want, but if the engine cannot utilize the increase, it will become a dog and will not perform. Other items such as increased exhaust flow (ie: headers), head port work, and large cylinder displacement will be need to fully utilize such a setup.

There is another common setup called a Tri-Duce. This was General Motors' version of this setup, but worked much the same way. You could find the Tri-Duce mainly on Corvettes and Pontiacs

  • So di the other two carbs open together or sequentially? – Zaid Jan 9 '16 at 13:47
  • @Zaid - I believe they open together. If they didn't you'd starve certain cylinders, which would cause issues (obviously). Think of it as opening a four barrel carb ... just they are cut in half. – Pᴀᴜʟsᴛᴇʀ2 Jan 9 '16 at 13:53
  • Infact, in the above image, the carbs which are used are just 1/2 of a Holley 4-barrel carburetor. With three halves, you get a six pack :D – Pᴀᴜʟsᴛᴇʀ2 Jan 9 '16 at 14:43
  • @Zaid - I have confirmed that an original 440 Six Pack came with vacuum secondaries on the outboard (front and back) carbs. You can actually see the vacuum secondary spring casing on the front one here (far side of the carb). The source was from a show called Graveyard Cars S4E18. The owner of the shop in the show (Mark Worman) is strictly a Mopar guy ... knows them inside and out. I'm not sure, but the above image may have come from that episode ... it looks like it. – Pᴀᴜʟsᴛᴇʀ2 Jan 9 '16 at 19:38
  • Excellent answer. There was also a smallblock six-pack, the 340 c.i.d.: allpar.com/mopar/mopar340.html – kmarsh Dec 17 '16 at 15:08
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The Mopar sixpack motors where the top of the street motor line ups and the 440 sixpacks would run right with the street Hemis. Sixpacks where three two barrels in a row and would deliver more power than any single four barrel at the time. As carburetors got larger, the sixpack was no longer as propeller. They can be tricky to tune, but in the right hands can be an awesome set up.

  • Propeller? What does that mean? – Hobbes Dec 17 '16 at 11:45

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