Vacuum Throttle Opener
See Figures 1 and 2
- Connect a tachometer to the engine. Run the engine until hot, then shut it OFF and remove the air cleaner assembly.
- Disconnect the vacuum sensing tube F from the servo diaphragm, then connect a vacuum hose between the vacuum tap on the intake manifold and the diaphragm.
- Disconnect the vacuum line that runs from the carburetor to the distributor at the distributor, and plug the open end.
- Start the engine and read the tachometer. Engine speed should be 1,300-1,500 rpm. If the speed is not to specification, turn the throttle opener adjusting screw to bring engine speed within the range.
- Reconnect the distributor and servo diaphragm vacuum lines, then disconnect and plug the vacuum line going to the anti-afterburn valve. Disconnect the vacuum line going from the intake manifold to the vacuum control valve, and tee in a vacuum gauge as shown.
- Start the engine and accelerate to 3,000 rpm. Watch the vacuum gauge and release the throttle. After a rapid rise in vacuum, the gauge reading should stabilize at 22.0-22.8 in. Hg (559-579mm Hg) for a few seconds while the system gradually closes the throttle, then drop off.
- If vacuum does not stabilize in the right range, loosen the locknut and turn the adjusting screw in the end of the vacuum control valve until vacuum is in