Strindberg carb: how to adjust bypass valve, screw covered?

[Sbarron]

Just rebuilt Stromberg carb bypass valve. How do you adjust them, the screw is covered with a brass colored cover. Does this come off to expose the screw?

Thanks
Scott

[RogerFrench]

The bypass valve is only used on Federal emission-control carbs, and so far as I am aware, is not adjustable. It opens under conditions of high manifold vacuum, on the overrun for example, going downhill with the throttles closed. As it opens it reduces the manifold vacuum below the level that causes pollution.

[Sbarron]

Thanks, i realize how it works and what it is for but when it is rebuilt the spring needs to be put under the right tension. Early cd carbs have the screw covered and later ones have the screw head exposed. There is a procedure for turning the screw to adjust the idle once it is rebuilt but nobody ever says how to take the cover off to expose the screw head.

Thanks anyway.

[RogerFrench]

Thanks, i realize how it works and what it is for but when it is rebuilt the spring needs to be put under the right tension. Early cd carbs have the screw covered and later ones have the screw head exposed. There is a procedure for turning the screw to adjust the idle once it is rebuilt but nobody ever says how to take the cover off to expose the screw head.

Thanks anyway.

I see, though not quite. Surely the valve is closed at idle?