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Larry

Yes, Dashpots were one of the first of many things added to carburetors to reduce emissions. When you close the throttle on a carburetor the high vacuum draws in lots of fuel making for a very rich mixture not a good thing for emissions but the popping and occasional back fire when running open exhaust was cool. The dash pot held the throttle slightly open for a short time after you let off the gas to let the engine slow down and the high vacuum subside. It also helped keep automatic transmission cars from stalling. In a modern fuel injected engine holding the throttle open for that reason is unnecessary. The computer calculates the correct amount of fuel based on throttle position and manifold absolute vacuum and other info so when there is lots of vacuum i.e.: the throttle is closed and the car is pushing the engine the computer just stops firing the injectors all together.

My guess on why the X has a Dashpot is that the EACV would have trouble controlling the amount of air to bypass the throttle when the vacuum is very high. So by holding the throttle open and letting the high vacuum subside the EACV does not have to try to control the amount of air bypass at a high differential pressure.

Briank

<blockquote data-quote="Briank" data-source="post: 164750" data-attributes="member: 7588">Larry Yes, Dashpots were one of the first of many things added to carburetors to reduce emissions. When you close the throttle on a carburetor the high vacuum draws in lots of fuel making for a very rich mixture not a good thing for emissions but the popping and occasional back fire when running open exhaust was cool. The dash pot held the throttle slightly open for a short time after you let off the gas to let the engine slow down and the high vacuum subside. It also helped keep automatic transmission cars from stalling. In a modern fuel injected engine holding the throttle open for that reason is unnecessary. The computer calculates the correct amount of fuel based on throttle position and manifold absolute vacuum and other info so when there is lots of vacuum i.e.: the throttle is closed and the car is pushing the engine the computer just stops firing the injectors all together. My guess on why the X has a Dashpot is that the EACV would have trouble controlling the amount of air to bypass the throttle when the vacuum is very high. So by holding the throttle open and letting the high vacuum subside the EACV does not have to try to control the amount of air bypass at a high differential pressure. Briank</blockquote>

[QUOTE="Briank, post: 164750, member: 7588"] Larry Yes, Dashpots were one of the first of many things added to carburetors to reduce emissions. When you close the throttle on a carburetor the high vacuum draws in lots of fuel making for a very rich mixture not a good thing for emissions but the popping and occasional back fire when running open exhaust was cool. The dash pot held the throttle slightly open for a short time after you let off the gas to let the engine slow down and the high vacuum subside. It also helped keep automatic transmission cars from stalling. In a modern fuel injected engine holding the throttle open for that reason is unnecessary. The computer calculates the correct amount of fuel based on throttle position and manifold absolute vacuum and other info so when there is lots of vacuum i.e.: the throttle is closed and the car is pushing the engine the computer just stops firing the injectors all together. My guess on why the X has a Dashpot is that the EACV would have trouble controlling the amount of air to bypass the throttle when the vacuum is very high. So by holding the throttle open and letting the high vacuum subside the EACV does not have to try to control the amount of air bypass at a high differential pressure. Briank [/QUOTE]

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