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Author Topic:   2bbl vs 4bbl carb
Dirt Full Roller

Total posts: 46
posted March 05, 2003 09:02 AM
does anyone think i'm crazy for using a 2bbl holley 4412 over a quadrajet, even though the rules allow either one? 3/8 banked clay oval. 355 sbc,.488 lift cam, pure stock heads. i see so many cars choking out on monster carbeurators.

Dirt Forum Champ
Total posts: 1565
posted March 05, 2003 09:19 AM UIN: 54865418
i'm not a real big fan of a qjet i would run a 4412.

Dirt Forum Champ
Total posts: 620
posted March 05, 2003 09:24 AM
a properly set up q-jet will smoke any 2 bbl.

Dirt Full Roller

Total posts: 46
posted March 05, 2003 10:45 AM
i'm being told that this 4412 carb is too small, only 500cfm. but i've seen it before. too much carb!

Dirt Maniac

Total posts: 173
posted March 05, 2003 03:02 PM
Can you run ANY 2brl? I think C&S has like a 900cfm 2holer. You'd probably be a reson for a new rule in a couple of weeks though.

Donnie Ross
Dirt Maniac

Total posts: 109
posted March 05, 2003 07:12 PM
It is virtually impossible to over carb with quad they will only supply what the engine can use due to the secondary design,that is why gm could use the same carb on every thing from a 305 to a 454.if set up correctly their is no comparison between the two even a c&s 890 is only as big as the secondarys on an 850 quad 2 inch butterflies
save the $800.00 and call KP lugnut or Earl parker they will help you out even if all you need is advice both great guys and far smarter than me on this subject.

Dirt Forum Racer

Total posts: 89
posted March 05, 2003 08:18 PM
People don't like the QJ because they don't know how to tune it. I finished second in Street Stock points one year when Holley four barrels were legal and I was running a Quadrajet. I just gathered up 3 or 4 carbs and pulled the jets and metering rods out. Becuase we ran racing gas I used a larger jet and a thinner metering rod to get the mixture right. Run an older non-emission one if you can. Learn to read plugs.

The benefit of the QJ is that the airflow is regulated by the air flap on the secondaries. Tightening and loosening the spring makes the secondaries open sooner or later. If it's tacky you loosen the spring. Slick track, tighten the spring. Small increments only. Buy a QJ book and the answers are in there. Getting the rods lined up to put the top on is the only real hassle.

A two barrel is tested at 3 inches of water versus a four barrel that is tested at 1.5 inches. That means the 500 2 barrel flows the same air as a 333 cfm four barrel.

Good luck,

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Dirt Freak

Total posts: 310
posted March 05, 2003 08:21 PM
Most motors are over carbed not to say a 4412 is better or worse you need to speak to someone to find out how much you need This an area where the more is better is not always true you can have a 4412 worked and it will do well with the right cam and heads as will the Qaud

Dirt Forum Champ
Total posts: 620
posted March 05, 2003 10:47 PM
excellent point superdave, most guys don't know that 2 bbls. and 4 bbls. are rated different.

Dirt Full Roller

Total posts: 46
posted March 06, 2003 06:38 AM
thanks for all the great replies.

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