Chuck
31.05.2021 12:58:02
What is the Idle Compensator and do you need it installed? here
See full version: Rochester 2 Jet Idle Circuit
What is the Idle Compensator and do you need it installed? here
Adjusting the screws don’t make any difference? more
The idle air compensator is used on some carburetor models to offset enrichment effects caused by excessive fuel vapors from fuel percolation, during extreme hot engine operation. here
The compensator valve is operated by a bi-metal strip that senses temperature. During extreme hot engine operation, excessive fuel vapors entering the engine manifold cause richer than normally required mixtures, resulting in rough engine idle and stalling. At a certain predetermined temperature, when extra air is needed to off-set the enriching effects of fuel vapors, the bi-metal strip bends and unseats a valve which uncovers the air channel leading from the carburetor venturi to below the throttle valves. At this time, just enough air is added to the engine to offset the richer mixtures and maintain a smooth engine idle. When the engine cools and the extra air is not needed, the bi-metal strip closes the valve and operation returns to normal mixtures.
Don’t have a vacuum gauge (not sure you should be working on your engine without one)? Follow the same sequence but instead of vacuum increase and drop, listen for the RPM to increase, or drop. more
What is the Idle Compensator and do you need it installed? here
Adjusting the screws don’t make any difference? more
The idle air compensator is used on some carburetor models to offset enrichment effects caused by excessive fuel vapors from fuel percolation, during extreme hot engine operation. here
The compensator valve is operated by a bi-metal strip that senses temperature. During extreme hot engine operation, excessive fuel vapors entering the engine manifold cause richer than normally required mixtures, resulting in rough engine idle and stalling. At a certain predetermined temperature, when extra air is needed to off-set the enriching effects of fuel vapors, the bi-metal strip bends and unseats a valve which uncovers the air channel leading from the carburetor venturi to below the throttle valves. At this time, just enough air is added to the engine to offset the richer mixtures and maintain a smooth engine idle. When the engine cools and the extra air is not needed, the bi-metal strip closes the valve and operation returns to normal mixtures.
Don’t have a vacuum gauge (not sure you should be working on your engine without one)? Follow the same sequence but instead of vacuum increase and drop, listen for the RPM to increase, or drop. more
Set the double-ended square to 1 inch and place it on the air horn with the measuring rod resting on the idle vent cam. Open the throttle valve until the vent valve just closes. Bend the tang on the pump lever until the cam just touches the measuring rod on the double square. more
Connect the tachometer to the engine by following the manufacturer's directions. Connect the vacuum gauge to a "manifold" or constant vacuum source. Start the engine and take it to normal operating temperature. Set the idle speed to 850 rpm with the idle-speed screw. Note the reading on the vacuum gauge and turn one idle-mixture screw clockwise a half-turn and note the change on the vacuum gauge. If the vacuum reading increases, turn the other idle-mixture screw clockwise a half-turn. Note the vacuum gauge reading. If the gauge continues to climb, adjust each idle-mixture screw in another quarter-turn. If the engine stumbles or the vacuum drops when turning the idle-mixture screws clockwise, turn both screws out a half-turn and note the gauge reading. [links]
The Rochester 2G carburetor has two bores, two venturis and two separate but identical metering systems. The two-bore carburetor is normally used on V-8 engines where each bore supplies the air/fuel mixture to four cylinders through a divide intake manifold. The model 2G was equipped with a manual choke and was primarily used on trucks and marine engines. The 2G carburetor was a popular choice for the "Tri-Power" triple carburetor muscle cars of the 1960s. Routine adjustment of the 2G carburetor can be done without removing the carburetor and will keep it operating at peak efficiency.
Shift the transmission into "park" if it is an automatic transmission or "neutral" if it is manual. Chock one tire and set the parking brake so the vehicle will not roll. Remove the air cleaner assembly and set it aside.
Question is. he will tune the carburetor on land. not on the water which will not put any load on the PROP..
As someone else posted, if you're dealing with fuel (or ignition, or carb, or mechanical) problems, getting the idle set correctly will be difficult, if not impossible. here
OK . this was a worst case senario but you got to be prepared