Type: R4-4MV Quadrajet Qjet Number: 7042244: CU: 4-467 General Picture of a R4-4MV Actual. Referenced by; Rochester 7042244 This Site Designed By. Rochester M4MC Carburetor Manual for 1975-1980 Oldsmobile. Comprehensive factory service information for Rochester Quadrajet M4MC carburetors. Rochester Carbs Quadrajet parts page many hard to find parts Jets chokes pulloffs rods fuel fittings. Quadrajet 4MV carburetor rebuild kit. Includes instructions and new flange gasket. Fits Buick, Chevrolet & Pontiac1968-74 vehicles.
Rochester Carbs Rochester Quadrajet Common Problems and Decoding by George Nenadovich The Rochester carb is the most common carb found in GM cars and trucks from the 1960's to the mid-1980's when they were replaced by fuel injection units. If the carb is maintained properly, it will deliver years of service. There are a few problems with the Rochester carbs as they get older and/or are not maintained.
A common problem is the fuel filter inside the fuel inlet housing becomes plugged with debris from dirty gasoline. This prevents the float bowl from filling quickly and results in poor engine performance. This filter is not an ideal candidate since it is made of paper and can not be seen unless the filter is removed from the housing.
The best filter to use is a glass filter connected in-line between the fuel pump and carb. This filter allows you to see if the fuel pump is working as well as if there is any debris in the fuel. Another problem is the cam that raises the secondary metering rods when the air valves open. This small heart shaped plastic cam is located between the secondary air valves on the air valve shaft.
It is common for this part to break preventing proper operation of the secondary air valves leading to a bog. Another problem associated with the secondary air valves is the vacuum secondary break. Gobi 3000 Windows 7 Driver. This small vacuum break is located on the passenger side of the carb. These small diaphragms rupture after years of exposure to heat and result in the secondary air valves flopping open causing a bog. A couple of other problems but not common are the carb being bolted to the intake with excessive torque and fuel well plugs leaking.
If the carb is overtightened with the four bolts mounting it to the intake the air horn will be bent creating fuel leaks and vacuum leaks. Always change the base gasket when installing a rebuilt carb for it to create an air-tight seal between the carb and intake. The fuel well plugs can leak and the best way to fix them is to use an epoxy to seal both wells. The wells are located under the bottom of the fuel metering rods. Rochester Quadrajet Number Decoding All Quadrajet carbs have numbers stamped on them on the driver's side rear secondary. It is visible when the secondary throttle actuator is opened or the carb is held at an angle. These numbers, 7 digits, indicate what engine the carb is from as well as manual or automatic transmissions, California emissions carb.
See photos below for number location. The arrow is pointing to the numbers stamped on the driver's side secondary body. The numbers here are a little difficult to read but are 7043240.
This particular carb is from a 1973 (fourth digit from the left is year, 3), Buick (6th digit is a 4 which means Buick), 455 (the last three digits from the chart below indicate an 800 cfm carb) The sixth digit can be one of the following depending on make: 0,1,2 Chevrolet, GMC or truck 3 Cadillac 4 Buick 5 Oldsmobile 6 Pontiac Buick Quadrajet Codes YEAR CARB # ENGINE TRANS ---- ------- ------ ----- 19 400 M 7027146 400 A 7027149 400 w/A.I.R. M 7027147 400 w/A.I.R.
A 19 350 M 7028244 350 A 7028243 400 M 7028242 400 A 7028240 430 A 19 350 M 7029244 350 A 7029243 400 M 7029242 400 A 7029240 430 A 19 350 M 7040244 350 A 7040243 455 M 7040240 455 A 7040246 455Stg1 A or M 7040247 455Rivi A 19 350 M 7041544 350 A 7041243 455 M 7041540 455 A 7041242 455Stg1 A or M 19 350 M 7042244 350 A 7042243 455 M 7042240 455 A 7042242 455Stg1 A or M 19 350 M 7043244 350 A 7043243 455 M 7043240 455 A 7043242 455Stg1 A or M Decoding Metering Jets and Rods When looking at the jets, you will notice the jet has two digits stamped on the surface. Download Ibm Websphere Transformation Extender Design Studio V8 0 [iso][english]. These indicate the diameter of the orifice. For example, 67 indicates a opening with a diameter of 0.067 inch. The part numbers for these are as follows: 7031966 indicates a metering jet with a 0.066 inch opening. Jets run from 66 to 78. So the part numbers will be in the form of 70319xx where xx indicates the number stamped on the jet.