Rochester Monojet Carburetor

The 1MV monojet carburetor is a single down draft unit using a triple ventuir in conjunction with the plain tube nozzle. The main venturi is 1 7/32″ in diameter and the throttle bore is 1 7/16″.
Fuel flow through the main metering system is controlled by a main well air bleed and a fixed orifice jet. A venturi velocity power enrichment system is used to provide good performance during moderate to heavy acceleration and at higher engine speeds.
An exhaust gas recirculation, E.G.R. system controls oxides of nitrogen emissions. The E.G.R. valve is operated by a vacuum signal taken from the carburetor throttle body.
A vacuum supply tube installed in the carburetor throttle body connects by a passage to timed vertical ports located in the bore of the throttle body and float bowl. The ports provide a vacuum signal to the E.G.R. valve in the off idle and part throttle operation of the carburetor.
The E.G.R. valve, mounted on the intake manifold, circulates a metered amount of exhaust gases to the combustion mixtures to lower peak combustion temperatures, thereby reducing oxides of nitrogen during these ranges of engine operation.

The E.G.R. system is not in operation during the engine idle.

A pleated internal paper fuel inlet filter is mounted in the float bowl behind the fuel inlet nut to give maximum filtration of incoming fuel.

The carburetor has an aluminum throttle body, a thick throttle body to bowl insulator gasket, and a internally balanced venting through a vent hole in the air horn which leads into the bore beneath the air cleaner. The float bowl is externally vented under extreme conditions through a pressure relief valve system.

The carburetor part number is stamped on vertical section of float bowl, next to fuel inlet.

An idle stop solenoid is used to control idle. The solenoid is electrically  controlled through the ignition switch. When the ignition switch is tunred off, the solenoid is denergized, allowing the carburetor throttle valve to close further, preventing the engine from running after the ignition switch is turned off. On manual transmission models, the  solenoid also deenergizes when the clutch is disengaged.

Rochester Monojet Identification

Monojet Identification

1980 Monojet 1ME Exploded View & Parts List

1981-85 Monojet 1ME Exploded View & Parts List

1985 & Later Monojet 1MEF Exploded View & Parts List

Float Level Adjustment

Monojet Float Level

Fast Idle Cam Adjustment

Monojet Carburetor

Vacuum Break Adjustment

Monojet Carburetor

Choke Coil Lever Adjustment
Quadrajet Adjustment

Trouble Shooting the Monojet M MV Carburetor

Adjust the Idle Mixture


Recent Posts

Floats

Floats perform an important function in maintaining the correct level of fuel in the float bowl by opening and closing an internal inlet valve. If the float develops a leak, it will sink below its ideal level and excess fuel will enter the bowl. This causes the engine to run rich and probably causes leakage of gasoline out of the carburetor, increasing the risk of engine fires. In a carburetor rebuild be certain to examine the old float for damage or corrosion. You can also test your float for leakage to determine if it needs to be replaced. Repairing old floats is difficult, especially in light of the need to avoid increasing the weight of the float with the addition of solder. Adding weight changes the floatation characteristics of the float.

We have one of the Internet’s widest selections of floats including all floats that remain available and many that are extremely hard to find. We have floats for all of the major name brands of carburetors. These floats are made in the U.S.A. and designed and built to the highest quality standards, including both brass and nitrophyl floats. In some applications, both are available to choose between. We do recommend changing all old nitrophyl floats at the time of a carburetor rebuild, and many mechanics change all floats during rebuilds.

From Holley, Carter, and Motorcraft to Stromberg and Zenith floats, we have them all, including a wide selection of Rochester and Marvel Schebler floats. If it is time for a float replacement in your classic car, scroll our selection and find your carburetor float at a price that will make you smile.

Float Problems and Their Diagnosis:

With brass floats, the floating “pontoon” is typically constructed of at least two brass sections soldered together along a seam. Then a tiny hole used to equalize internal and external temperatures is soldered shut to complete the assembly process. Since all of these points are submerged in gasoline during engine operation, leakage problems can later occur at any place that was soldered. Repairing these floats is quite challenging and replacement is usually preferred unless the float is no longer available.

If your engine is the least bit hard starting after it has warmed up, or if your exhaust has a rich gasoline odor, you probably have carburetor problems, and a bad float is one of the possibilities. Other symptoms include poor gas mileage and, of course, if the engine is flooding.

  1. Is Ethanol Good for my Car? 3 Replies
  2. Adjusting the Idle Mixture Leave a reply
  3. Mustang You Gotta Love 1 Reply
  4. Mobile Responsive Web Store 1 Reply
  5. Rochester 2 Jet Fuel Percolation 6 Replies
  6. Car Stalls When Putting in Gear Leave a reply
  7. Carter AFB Flooding Problem 4 Replies
  8. The B&B or Ball & Ball Accelerator Circuit Gone Bad Leave a reply
  9. Work on Carburetor While On Car 1 Reply