Quote:
Originally Posted by luzl78
danny you're killing me. that's the carb i need for my monte. a few months late on the build but the 4 speed carb for my car. i was gonna put the 70 holley ls6 4 speed 70 l78/ls6 on the car? don't know which would work better. gonna have a hot motor in it.whats the de-acceleration valve do? is that a 4 speed thing?
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Yes it is a 4 Speed only addition, It's also called a dashpot.
It's purpose is to slow down throttle closing so that air can mix with the gas and lower hydrocarbon emissions. If the throttle blades are snapped shut, especially after acceleration as you'd see on a manual trans motor upon shifting, then the fuel that was in the manifold doesn't get enough air, and the mixture goes very rich for a moment. When the dashpot slows the throttle return, the fuel has enough air to burn in the combustion chamber and the mixture burns cleaner. They weren't needed on automatic trans cars because you don't have the throttle open/closed/open during shifting like a manual.