How do I identify my Quadrajet carb?
ID numbers for a Rochester Quadrajet carburetor are found next to the throttle level. There should be a metal disc affixed to the carburetor for those in the 1965 to 1968 range, and the number was stamped into the unit without a metal disc on the later-year models. This is the number you need for decoding.
What CFM is a Quadrajet carburetor?
Most Quadrajets were capable of 750 cu ft (21,000 l)/min (cfm) maximum, but some rare Buick and Pontiac models were capable of 800 cu ft (23,000 l)/min for use on high performance engines, and most 1984-1987 pickup trucks were also equipped with the 800-cfm carb.
Are Quadrajet carburetors any good?
The truth is, a properly tuned Quadrajet can be just as efficient and reliable as a bolt-on substitute performance carburetor. The Quadrajet has many model designations; the most adaptable units were designated as 4M, 4MC and 4MV, and most were rated at 750cfm until 1972 when their rating was increased to 800cfm.
How do I identify a Rochester 2 jet carburetor?
All Rochester carburetors are identified by a seven- or eight-digit part number. The earliest units, made before mid-1968, had a triangular metal tag attached to the fuel bowl. The seven-digit part number is listed on the tag. You occasionally find original carburetors with an anodized tag of various colors.
What size is my Quadrajet carburetor?
As we mentioned, the Quadrajet is a spread-bore design carburetor, using 1-3/8″ primary bores and 2-1/4″ secondaries. The smaller primary bores give the carburetor better idling and low-load fuel economy. The larger secondary bores are regulated by tapered metering rods which set the air to fuel mixture.
Who makes the Quadrajet carburetor?
Rochester Carburetor Division
The Quadrajet four-barrel carburetor was produced by the Rochester Carburetor Division of General Motors from 1965-’90. It was produced in many forms, including electronic-control from 1980-’90, for a wide variety of GM applications.
What carbs replace Quadrajet?
New Holley Sniper EFI is Direct Replacement for Q-Jet Carb. Holley/MSD is thrilled to announce the release of Sniper EFI Systems for Quadrajet applications, which eliminate the need to continually rebuild 50-plus-year-old Quadrajet carburetors on classic Chevys, Pontiacs, Buicks, Oldsmobiles, and GMCs.
How do I know what Rochester carburetor I have?
All Rochester Quadrajet carburetors are identified by a seven- or eight-digit GM part number. On units made before mid-1968, the part number was stamped around the outside edge of a round metal tag attached to the fuel bowl.
Where is the part number on a Quadrajet carburetor?
(EARLY) Figure 3 Carburetor Identification Tag -Early Models carburetors have no tag but include the part number stamped vertically on the left rear corner of the float bowl casting adjacent to the secondary pick-up lever (Figure 4).
When was the Quadrajet 4MV carburetor first released?
The fuel flow through the nozzles is thereby controlled in direct pro portion to air flowing through the secondary bores. There are two basic carburetor model designs: First released in 1965, the 4MV is an automatic choke model designed for use with a manifold mounted thermo static choke coil.
What does the letter E stand for on a Quadrajet?
So, a 4M is a Quadrajet, and a 2M is a two-barrel Dualjet. The next letter, V, C, or E stands for the type of the choke’s thermostatic coil. If there is an E before the number 4, that designates an electronically-controlled carburetor. If it has an M before the 4, that’s a “modified” Quadrajet, built starting in 1975.
What’s the difference between a 4m and 2m Quadrajet?
Early Rochester four barrels were a “G” series. So, a 4M is a Quadrajet, and a 2M is a two-barrel Dualjet. The next letter, V, C, or E stands for the type of the choke’s thermostatic coil. If there is an E before the number 4, that designates an electronically-controlled carburetor.