2x4 bbl

[Stallion]

What exactly does this notation mean? I assume it's for the carb specs. Does it mean two of four barrels? So eight barrels in all? :confused Can you even have eight barrels for the carb? Can somebody clear up my misconception on this?

 

[JRMaroon]

Two four barrel carbs on one engine.

Also known as dual quads.

Jeff

 

[Stallion]

That's what I thought. But that's...crazy. :eek That's a lot of fuel getting pumped into there. I assume this is desired? (provided that you don't care about gas mileage)

 

[Tuna]

Very large single 4-barrel carbs are less fuel efficient when just cruising than a dual quad set up with the same total CFM. So, dual quads are a good thing for street cars. Same can be said of 3 deuces. So, this is good for fuel mileage!!!

With progressive linkage, the engine is using only 2 of the 8 barrels for normal driving but all 8 open when needed.

This lead to the development of the QuadraJet 4-barrel which had 2 small primary barrels and 2 huge secondaries.

Of course dual quads and 3 deuces are harder to get balanced right than a single carb. One of the trade offs of the set up.

 

[Stallion]

I don't know what I have in mine. I think a four barrel, but not sure. Thanks for the info!!

 

[Tom73]

I don't know what I have in mine. I think a four barrel, but not sure. Thanks for the info!!

The '78 Vettes came with a q-jet 4-barrel carb, 750 cfm.

Let me throw in two cents here. The 2x4s are old tech. Left over from when the largest carbs you could get were about 400 to 500 cfm, the AFBs. Back then they would put two of them on an engine to get 800 to 1000 CFM. But then Holley came out with, what were at the time, huge carbs. That killed the 2x4 set ups. With the one carb you could be much more effecient fuel monitioring/flow.

Today you only see 2x4s on show cars or on moster ram intakes at the drags.

tom...

 

[Stallion]

The '78 Vettes came with a q-jet 4-barrel carb, 750 cfm.

Let me throw in two cents here. The 2x4s are old tech. Left over from when the largest carbs you could get were about 400 to 500 cfm, the AFBs. Back then they would put two of them on an engine to get 800 to 1000 CFM. But then Holley came out with, what were at the time, huge carbs. That killed the 2x4 set ups. With the one carb you could be much more effecient fuel monitioring/flow.

Today you only see 2x4s on show cars or on moster ram intakes at the drags.

tom...

Why would you want this on ram intakes for drags? What's the idea behind that?

 

[Tom73]

Why would you want this on ram intakes for drags? What's the idea behind that?

Put two 800 cfm holley's on top of a ram intake and it could drop a huge amount of fuel into that engine and make big hp numbers.

tom...