C3-1971: cold engine idle mixture?

[Greg F.]

The valve seals were replaced in my car about 6 months ago. That seemed to fix the small amount of blue/white smoke after start up. I recently had work done to my original carburetor. I had missing parts on the choke assembly. I had these put back on. When I start the car, it does the fast idle as it should. I've notice it is blowing blue/white smoke again. After it warms up and the idle goes to 700 rpm, the smoke stops.

Someone mentioned I might have the wrong cold engine idle mixture? Could this be the case and is it just a matter of an adjustment? Any details are appreciated.

Thanks,
Greg

[Robert E.]

Re: C3-1971: cold engine idle mixture?

Greg, make sure your pcv valve is correct and functional. It maybe stuck and sucking oil into the carb and burning it.

Robert
41801

[Jack H.]

Re: C3-1971: cold engine idle mixture?

There's only one adjustment for air/fuel mixture and that's the screw based needle valves on the front base of the QJet's throttle plate.

Cold idle mixture is based on how far the choke plate closes when you set the choke by pushing the accelerator pedal all the way to the floor prior to initial engine crank. Once the engine fires, the mixture gets progressively leaner based on the operation of the choke pull-off (vacuum device on the LH side of the carb) and the expansion of the bi-metal divorced choke that raises the carb's choke plate in steps until the engine is fully warmed up and the choke plate is fully open.

The theory of operation + adjustments for the various components of the QJet are described in the Engine Fuel section of your copy of the 1971 Chassis Service Manual.

[Greg F.]

Re: C3-1971: cold engine idle mixture?

There's only one adjustment for air/fuel mixture and that's the screw based needle valves on the front base of the QJet's throttle plate.

Cold idle mixture is based on how far the choke plate closes when you set the choke by pushing the accelerator pedal all the way to the floor prior to initial engine crank. Once the engine fires, the mixture gets progressively leaner based on the operation of the choke pull-off (vacuum device on the LH side of the carb) and the expansion of the bi-metal divorced choke that raises the carb's choke plate in steps until the engine is fully warmed up and the choke plate is fully open.

The theory of operation + adjustments for the various components of the QJet are described in the Engine Fuel section of your copy of the 1971 Chassis Service Manual.

Thanks Jack and Robert!

Jack - I'm not very good with motors let alone carburetors. I appreciate your explanation. Could this be a reason why I'm experiencing the blue/white smoke?

Thanks again.