Dash pot
Registered User
Joined: Aug 2013
Posts: 111
From: Minneapolis, MN
My car has one and I think they put them on AC cars. When not properly adjusted my car would kill on hot days with the AC running. It just acts as a cushion so the throttle doesn't close too quickly.
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1956 Super 88
Joined: Feb 2014
Posts: 14
From: Northwest Florida
Mine has a vacuum line coming in the front, and a threaded stem extending out the other side. The idle is increased when you screw it out?
Everything I have read on this thing says what you guys are telling me, I just can't comprehend this one. I don' t see how vacuum could thread and un thread to soften the throttle closure.
Everything I have read on this thing says what you guys are telling me, I just can't comprehend this one. I don' t see how vacuum could thread and un thread to soften the throttle closure.
Registered User
Joined: Aug 2013
Posts: 12,655
From: Evansville, IN
Gentlemen, you may be confusing the idle stop solenoid with the vacuum dashpot. Or perhaps the idle stop is also vacuum. I will attempt some insight, and my betters can correct as needed.
A dashpot is open to atmosphere, with a large reservoir, and a small hole. This is basically a vacuum choke. You typically see these on the vacuum operated secondaries of the Quadrajet. The throttle plates are manual, but the air horn is vacuum operated. All these do, is when pulled, is stifle the air flow rate into the air driven circuit, just buying some time. It's like a set of bagpipes; big air bag, small hole; takes some time to push it all out.
Now the idle thing, that is not a throttle close rate buffer, that is a minimum throttle set fixture that is on when the car is on. When you shut it off, it lets the throttle close more, thus preventing dieseling. In a vacuum one, it is connected to engine vacuum, so it never eases off until the engine is shut off. Some, maybe most, are electrical, but same idea. The threaded part is a bolt is in the threaded end of the cylinder, and it has, on its other end, the base that is pulled by the vacuum or moved by the solenoid. The bolt is just screwed into it and is adjustable by the user.
I could have some or all of that wrong.
A dashpot is open to atmosphere, with a large reservoir, and a small hole. This is basically a vacuum choke. You typically see these on the vacuum operated secondaries of the Quadrajet. The throttle plates are manual, but the air horn is vacuum operated. All these do, is when pulled, is stifle the air flow rate into the air driven circuit, just buying some time. It's like a set of bagpipes; big air bag, small hole; takes some time to push it all out.
Now the idle thing, that is not a throttle close rate buffer, that is a minimum throttle set fixture that is on when the car is on. When you shut it off, it lets the throttle close more, thus preventing dieseling. In a vacuum one, it is connected to engine vacuum, so it never eases off until the engine is shut off. Some, maybe most, are electrical, but same idea. The threaded part is a bolt is in the threaded end of the cylinder, and it has, on its other end, the base that is pulled by the vacuum or moved by the solenoid. The bolt is just screwed into it and is adjustable by the user.
I could have some or all of that wrong.
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