2 bbl or 4? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

86SILVERADO · 01-05-2004, 01:13 PM

I have a 350 from a 76 suburban that I just put in my 67 C30 I can't decide if I should use the 2 jet setup or the quadrajet. I have the 1 3/8 venturi 2 bbl rated at 435 cfm which is plenty for my 350. I only have an emissions era quadrajet which I know I can get to work with a few modifications. I am mainly concerned with what will give me the best gas milage since I don't need massive power due to the sm420 trans and 4.10 rear end. Anyone with experience with the difference in economy between a 2 jet and quadrajet?

Don Smith · 01-05-2004, 06:17 PM

I've run them both. Currently running a quadrajet. I am getting slightly better fuel milage and much better driveability with the quadrajet.

dinnut · 01-05-2004, 07:03 PM

run the quadrajet. i got 2 trucks. one with the 4 and one with the 2. the 4 is so much better.

Tx Firefighter · 01-05-2004, 07:28 PM

I'll buy those 2bbl carbs from you guys who don't like them.

dinnut · 01-05-2004, 07:49 PM

really tx? ill be getting rid of the one i have on my 72 probably...
intake too. when i put my 4bbl intake and carb off my 70l... interested? its a replacement 2bbl built by holley they base cracked after about a week of use (pos plastic or something) and so we went to a junkyard found the correct carbeuretor dissasembled them and used the base plate off the steel junkyard carb on the holley...
i could sell it to you. i also have the rest of the junkyard carb sitting in my garage if interested...

Tx Firefighter · 01-05-2004, 09:26 PM

I love 2 bbl carbs. I use them for other things. I like them because I can usually pick them up for 5 or 10 bucks.

They are the Rodney Dangerfield of carbs. They get no respect.

dinnut · 01-06-2004, 10:37 PM

hmm interested in buying them tx?

Tx Firefighter · 01-06-2004, 10:45 PM

how much $?

and let's see some pictures..........

jewels. · 01-07-2004, 01:35 AM

this is interesting.... i am faced with this same decision.... my 2bbl carb is in need of being rebuilt, and i chose to stick with it over the 4bbl to keep better gas mileage and because of the price....

the 2bbl carb i have only cost me a few bucks, and a rebuild kit on it is about $20 (including the float).... so its pretty cheap to purchase and maintain....

my brother (a mechanic) told me that i would get better gas mileage with the 4bbl if i can keep my foot off the pedal (and thus out of the secondaries)....

but another mechanic told me that the two carbs are realistically the same when it comes to gas mileage because they both run two primaries most of the time.... he said that the way a carberator is adjusted affects the gas mileage more than whether or not it is a 2bbl or a 4bbl.....

does this make sense? comments anyone?

thanks!

jewels.

Longhorn Man · 01-07-2004, 01:58 AM

If you are talking quadra-jet, or edelbrock, then you'll probably get better MPG (keeping your foot out of it).
If you flip one of them over, you'll see the primaries are real small, all the CFM is in the secondaries.

01-05-2004, 01:13 PM	#1
86SILVERADO Registered User Join Date: Dec 2002 Location: Hills of Western Mass Posts: 626	2 bbl or 4? I have a 350 from a 76 suburban that I just put in my 67 C30 I can't decide if I should use the 2 jet setup or the quadrajet. I have the 1 3/8 venturi 2 bbl rated at 435 cfm which is plenty for my 350. I only have an emissions era quadrajet which I know I can get to work with a few modifications. I am mainly concerned with what will give me the best gas milage since I don't need massive power due to the sm420 trans and 4.10 rear end. Anyone with experience with the difference in economy between a 2 jet and quadrajet? __________________ 86 Silverado C10 back to 305 power! 67 C30 Dually Dump, with 350 transplant, Rockhauler 05 Duramax 3500 "If at first you don't succeed, try a bigger hammer" Member of the 1-Ton club!

01-05-2004, 06:17 PM	#2
Don Smith Registered User Join Date: Jul 2000 Location: Hampton, Ga, USA Posts: 217	I've run them both. Currently running a quadrajet. I am getting slightly better fuel milage and much better driveability with the quadrajet. __________________ 68 Short Stepside, 350, quadrajet, 700r4, 3:73 posi, power front discs, HEI, Factory Air, Tilt, Tach, accelerator cable instead of rod, sway bar. 96 Impala SS 97 Monte Carlo

01-05-2004, 07:03 PM	#3
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	run the quadrajet. i got 2 trucks. one with the 4 and one with the 2. the 4 is so much better. __________________ 70 longbed 496/th400/Ford 9"

01-05-2004, 07:28 PM	#4
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	I'll buy those 2bbl carbs from you guys who don't like them. __________________ I'm on the Instagram- @Gearhead_Kevin

01-05-2004, 07:49 PM	#5
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	really tx? ill be getting rid of the one i have on my 72 probably... intake too. when i put my 4bbl intake and carb off my 70l... interested? its a replacement 2bbl built by holley they base cracked after about a week of use (pos plastic or something) and so we went to a junkyard found the correct carbeuretor dissasembled them and used the base plate off the steel junkyard carb on the holley... i could sell it to you. i also have the rest of the junkyard carb sitting in my garage if interested... __________________ 70 longbed 496/th400/Ford 9"

01-05-2004, 09:26 PM	#6
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	I love 2 bbl carbs. I use them for other things. I like them because I can usually pick them up for 5 or 10 bucks. They are the Rodney Dangerfield of carbs. They get no respect. __________________ I'm on the Instagram- @Gearhead_Kevin

01-06-2004, 10:37 PM	#7
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	hmm interested in buying them tx? __________________ 70 longbed 496/th400/Ford 9"

01-06-2004, 10:45 PM	#8
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	how much $? and let's see some pictures.......... __________________ I'm on the Instagram- @Gearhead_Kevin

01-07-2004, 01:35 AM	#9
jewels. Registered User Join Date: Jul 2001 Location: Munster, IN Posts: 1,100	this is interesting.... i am faced with this same decision.... my 2bbl carb is in need of being rebuilt, and i chose to stick with it over the 4bbl to keep better gas mileage and because of the price.... the 2bbl carb i have only cost me a few bucks, and a rebuild kit on it is about $20 (including the float).... so its pretty cheap to purchase and maintain.... my brother (a mechanic) told me that i would get better gas mileage with the 4bbl if i can keep my foot off the pedal (and thus out of the secondaries).... but another mechanic told me that the two carbs are realistically the same when it comes to gas mileage because they both run two primaries most of the time.... he said that the way a carberator is adjusted affects the gas mileage more than whether or not it is a 2bbl or a 4bbl..... does this make sense? comments anyone? thanks! jewels. __________________ 68 C10 Red Step 350 my first child & main focus 58 3200 Apache LWB Step the upcoming project

01-07-2004, 01:58 AM	#10
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	If you are talking quadra-jet, or edelbrock, then you'll probably get better MPG (keeping your foot out of it). If you flip one of them over, you'll see the primaries are real small, all the CFM is in the secondaries.



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