Carb question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

O'l Buck · 02-26-2003, 02:53 AM

I've been looking and comparing for awhile now and am still scratching my head. Can anybody tell me how to ID a big block quadrajet?......What numbers denote CFM and so forth. I have a table that decodes the part number as far as year and make, but it don't tell me squat about CFM's. I'm talking about Rochester Quadrajet's by the way. Any help would be greatly appreciated. Thanks in advance.

ChevLoRay · 02-26-2003, 12:27 PM

There should be a number on the carburetor....like 702XXXX, or something like that. That number can be cross-referenced at some parts houses for kits. That cross-reference may also help determine what it came off of.

Another way is to find a listing of carb numbers based on vehicle and engine. Then, you just "go looking".

I think that I'd consider a new/rebuilt carb that is spec'd for your needs, i.e., you need a carburetor for a '68 Chevelle w/396, 350 horsepower.

Just suggestions....you asked.

lpaine · 02-26-2003, 12:54 PM

There were three basic quadrajets built from '65-late 70's, the 4-M with manual choke, the 4-MV with automatic choke with thermostatic coil on the manifold, and the 4-MC with automatic choke, but thermostatic coil and the choke housing mounted on float bowl. The i.d #s for your carb are stamped into the body casting of the carb by the throttle linkage. I'm guessing your's is a 4-MV, and if so it would be 750 or 800 c.f.m. When you get the i.d. #s you should be able to positively determine what it is. Hope this helps.

O'l Buck · 02-26-2003, 02:30 PM

I've got 4 carbs in the barn, and have 2 on vehicles that I'm running. I know what 2 of them came off of, and one of them is off of a 76 olds 455. I can find the years and makes by decoding the numbers on the throttle base plate, but my chart doesn't tell me what engine it was on or what the CFM is. is there a good way to tell?

02-26-2003, 02:53 AM	#1
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	Carb question I've been looking and comparing for awhile now and am still scratching my head. Can anybody tell me how to ID a big block quadrajet?......What numbers denote CFM and so forth. I have a table that decodes the part number as far as year and make, but it don't tell me squat about CFM's. I'm talking about Rochester Quadrajet's by the way. Any help would be greatly appreciated. Thanks in advance. __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska

02-26-2003, 12:27 PM	#2
ChevLoRay Old Skool Club Join Date: Jun 2001 Location: Benton, AR "The Heart of Arkansas" Posts: 10,880	There should be a number on the carburetor....like 702XXXX, or something like that. That number can be cross-referenced at some parts houses for kits. That cross-reference may also help determine what it came off of. Another way is to find a listing of carb numbers based on vehicle and engine. Then, you just "go looking". I think that I'd consider a new/rebuilt carb that is spec'd for your needs, i.e., you need a carburetor for a '68 Chevelle w/396, 350 horsepower. Just suggestions....you asked. __________________ Member Nr. 2770 '96 GMC Sportside; 4.3/SLT - Daily driven....constantly needs washed. '69 C-10 SWB; 350/TH400 - in limbo The older I get, the better I was.

02-26-2003, 12:54 PM	#3
lpaine Registered User Join Date: Oct 2002 Location: Parksville, B.C. Canada Posts: 637	carb i.d. There were three basic quadrajets built from '65-late 70's, the 4-M with manual choke, the 4-MV with automatic choke with thermostatic coil on the manifold, and the 4-MC with automatic choke, but thermostatic coil and the choke housing mounted on float bowl. The i.d #s for your carb are stamped into the body casting of the carb by the throttle linkage. I'm guessing your's is a 4-MV, and if so it would be 750 or 800 c.f.m. When you get the i.d. #s you should be able to positively determine what it is. Hope this helps. __________________ 1969 G.M.C 3/4 Ton 920 (Canadian Version) 307 3 speed, currently apart 1998 Chevy 1/2 ton ex cab V-6 5 speed 1967 Chevy SWB - project truck; not started just yet

02-26-2003, 02:30 PM	#4
O'l Buck Recovering Truck Driver Join Date: Mar 2002 Location: Orleans, NE USA Posts: 1,883	I've got 4 carbs in the barn, and have 2 on vehicles that I'm running. I know what 2 of them came off of, and one of them is off of a 76 olds 455. I can find the years and makes by decoding the numbers on the throttle base plate, but my chart doesn't tell me what engine it was on or what the CFM is. is there a good way to tell? __________________ 67 K-20 350, SM465, Eaton rear, 4.56 no spin option 00 Dodge 2500 4x4, 24V cummins, 5 speed Chad South Central Nebraska



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