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

Tips on Removing Frozen Parts

Over the years I have learned the hard way how to remove screws & bolts that are frozen. Using the techniques below I seldom need any specialty tools for removing screw, bolts & nuts.

Here are some ideas that might help you:

Removing the Small Screws on the Choke, or Throttle Shaft

Take your time removing these screws. It will pay off big time. These screws are usually mushroomed on the threaded end. Using a dremmel tool, grind the threaded end flush with the shaft. Using a screw driver that fits the screw head well, twist the screw counter-clockwise. It is sometimes a good idea to turn the screw back in, then out again. This helps flush out rust particles. Don’t turn too hard, or the screw will break.

Not coming out? Put a block of some kind on the threaded end to prevent the shaft from bending, then hit the screwdriver with a hammer while you try to turn the screw. This will sometimes break the screw loose.

Still not coming out? Using a butane torch heat up the area around the outside of the screw. Don’t apply too much pressure, or you risk bending the shaft.




Did you break the screw? You will have to drill & tap. Using a drill bit (and a good one), just shy of the screw diameter, drill out the screw. If you do this carefully you will be able to remove the screw without damaging the threads. The trick here is to have a good set of small drill bits.

After inserting the new screws, you can mushroom the end, or as I do use thread locker.

Frozen Shafts

The best way to un stick frozen shafts is to heat the area outside of the shaft and tapping on the end of the shaft. The shaft will almost always come loose. If it doesn’t then it is most likely beyond repair.

Frozen Screws, Bolts or Nuts

When a screw is damaged to where a screw driver won’t hold, use a drift punch and hit it a few times with a hammer. This will cause the screw slot to shrink hopefully enough to allow the screwdriver to work. The banging will often times jar the screw.

For bolts use the same drift punch technique to see if the bolt comes loose. Avoid using 12 point sockets. A 6 point will give you a better grip. When a bolt start to loosen, then tightens up, stop. Try moving the bolt back and forth to help loosen it up.

Still frozen? Apply heat around the outside of the screw, bolt, or nut.

Always use good tools and the correct tool on nuts & bolts. That does not include a cresent wrench.

Nut or Bolt Has a Stripped Head

Use a flat file to file the flat parts and remove the mushroom edges. From there try a smaller socket or wrench. Sometimes moving from a US wrench to a metric wrench will do the trick, otherwise a vise grip will be in order. Again applying heat will probably help the nut, or bolt move easier.

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