7040205 Q-Jet Carb 4 Speed L34 396 LS5 454 Chevelle Corvette Nova Camaro DeCell Valve

[XXXGoldL34M20]

Rebuilt and ready to Install is this very tough to find 7040205 Quadrajet Carb with the rare De-Acceleration Valve. 4 Speed Manual application Only for the following non California ordered Q-Jet's >>>
-1970 Chevelle or El Camino SS 396 350 HP, LS5 454 360 HP or LS3 402 330 HP
-1970 Monte Carlo SS LS5 454 360 HP or LS3 402 330 HP
-1970 Corvette LS5 454 390 HP
-1970 Nova SS L34 396 350 HP
-1970 Camaro SS L34 396 350 HP

Brand New Fuel Filter with proper spring inside, new top round gasket, new vacuum pod.
The rest are rebuilt true Rochester parts.

Dated 0360 which is February 5 1970.

$1800 USD Shipping $50 Paypal "Friends"
Will sell without the de-cell valve for $1600
View photos for condition.

See *UPDATE* comment above as the De-Acceleration Dashpot Valve has been *SOLD* on it's Own.
Price now $1550

[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 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?

[XXXGoldL34M20]

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?

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.

[luzl78]

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.
Gotcha,I understand. Does a 4 speed Holley carb have the same kind of dashpot?

[XXXGoldL34M20]

Gotcha,I understand. Does a 4 speed Holley carb have the same kind of dashpot?

NO

[XXXGoldL34M20]

*UPDATE*
De-Acceleration Dashpot Valve has been *SOLD* on it's Own. Received an offer I could not refuse.
So I am lowering the Price of the Carb to $1550. The good news Is I will be throwing in another De-Acceleration Dashpot Valve that looks great when installed but has been modified because it was previously broken when it shipped out with another carb with poor packing by the seller I bought it from.
See Photos (Last Photo shows this valve on my own car to show it looks the part but also adjust the idle just fine).
At $1550 this is a very Fair Price for a rebuilt Carb.

[XXXGoldL34M20]

Some UPDATED Photos with the Dashpot installed on the carb. Attached to the Dashpot pole is a hard clear plastic tube that slides onto the end of the idler screw which will be included.
As you can see the Dashpot finish has been restored and installed on the Q-Jet it looks very good IMO.

$1550 USD plus $50 shipping. Takes the Carb with Dashpot included.

[luzl78]

i guess a nos dashpot is hard to come by?

[XXXGoldL34M20]

i guess a nos dashpot is hard to come by?

Last NOS one on eBay Sold for $600 Jeffrey D sold it.
Restored and re-plated one on eBay Sold for $400 Jim B sold it.
Today taking $325 for mine was a pretty good bargain compared to these completed ones mentioned above.

Jeff the one I put on the Carb now looks pretty damn good IMO, yes it was repaired but it plays the part real well IMO.

Pull that trigger !
Search these rebuilt 7040205's on eBay, most of them are at $2100 at the high end, sure you can be patient and maybe get one for $1500 re built on the low end but the date code may not be correct for your car.

[XXXGoldL34M20]

*SOLD* Thank You Jeff & sYc