QJet Dashpot

[SmokinBBC]

I still have the dashpot for my 70 Qjet. The dashpot is a little canister that has a rod up against the throttle lever. It pops out when the throttle is opened. When the throttle rests against it upon return to idle, the dashpot gradually bleeds down and collapses.

Anyone know how the internals work? Is there a diaphragm in there. Do these things deteriorate over time?

 

[lars]

The dashpot system was used on the California cars to lower emissions upon closing the throttle on manual transmission cars - it's simply an air bled device to prevent sudden closing of the throttle. I've never seen one go bad - they're very simple with a diaphragm and a small air blead hole internally.
Lars

 

[SmokinBBC]

Thanks Lars. It appears functional. I took it out a few months back and put in a normal idle screw. I don't really notice a difference.

 

[lars]

When it's working, it controls the rate of return-to-idle and prevents the throttle from being "slammed" closed. This slow and controlled rate of return-to-idle was annoying to many people, but it helped lower emissions by reducing the occurrance of lean misfire when the thorttle was closed at elevated rpm (on deceleration with manual tranny). Unless a customer requests that it be left in place, I usually replace them with a standard idle speed screw & spring.
Lars