prevents the engine being loaded when the accelerator pedal is depressed suddenly and then released. It accomplishes this by slowing the closing rate of the throttle as it approaches the idle position. This allows the engine to dissipate the raw fuel discharged into the intake manifold by the accelerating pump.
The dashpot uses a spring-loaded diaphragm to slow the final phases of throttle plate closing. When the accelerator pedal is released, the throttle return spring in the throttle linkage simultaneously closes the throttle plates. As the throttle lever moves closed, its initial travel is unimpeded. The throttle lever will close nearly to the idle position before it engages the dashpot. Then the dashpot adjusting screw located in the extension of the throttle lever contacts the end of the diaphragm rod of the dashpot. Initially the movement of the dashpot rod will be resisted by the return spring only. As the rod moves into the dashpot, however, the tapered step in the rod will seat in the dashpot
washer. Continued movement of the rod will then also cause a corresponding movement in the diaphragm. Thus, further movement of the rod will be resisted by the diaphragm compressing the return spring and the air in the diaphragm chamber. An air bleed in the diaphragm washer allows air to escape slowly from the diaphragm chamber. This allows the throttle lever to close completely to the idle position, but retards the speed of that closing.
When the throttle is opened, the above sequence of operation is reversed. The return spring returns the diaphragm and rod to their original position and a fresh charge of cushioning air is drawn into the diaphragm chamber.
A number of engineering changes have been incorporated in some later versions of the dashpot. These changes have been made solely to facilitate production practices. The principal of operation remains unchanged and the above description is still generally applicable.
OVERHAUL
1. INTRODUCTION
Follow the recommendations and overhaul procedures given in the Service Manual. This Supplement will list all exceptions to those procedures.
2. SPECIAL TOOLS
See the list of recommended tools in the Service Manual.
3. MASTER REPAIR KITS
Refer to the current Holley Carburetor Parts Catalog sheet for the carburetor being overhauled.
4. DISASSEMBLY
A. PREPARATION
Follow the recommendations contained in the Service Manual.
B. DISASSEMBLY - MAIN BODY FROM THROTTLE BODY
The following list contains all parts removed in separating the main body assembly from the
Figure 1. Disassembly-Throttle Body From Main Body .