Engine: 2.1 Carb B21A: Mixture screws

[Bob 1967]

Hi, a question on mixture settings .
On the intake manifold there is a screw that adjusts the air from the valve cover breather (number 2 )


On the carb (Pierburg 175 )there is the regular Air /fuel mixture screw (number 1).
How is a balance achieved between the two ?
The carb is running too rich at idle ,but when I reduce either it won't idle and when it does idle the plugs are black.

Is there an initial setting ?

It ran fine and clean ,but just as I finished getting everything else sorted (Driveline and engine mounts) ,it started acting up.
A carb strip and clean rebuild will follow.
" Fed up with Brrickk" (Father Jack)

Bob

[Othen]

Hi Bob,

The screw (2) is the slow running adjuster, (1) is the anti-dieseling circuit adjuster. Usually it is best to leave (1) alone with its factory setting and use (2) to adjust the tick-over. They sort of do the same thing - just that the anti-dieseling solenoid only acts on the circuit controlled by (1).



The mixture screw is the CO adjustment screw - an indented hexagon underneath the body, pointing directly upwards in the middle, I think a 7mm socket fits well (might be 8mm, I'll check my notes in the morn). It screws inwards to make the mixture leaner. It may have an anti-tamper plastic cap over it that you may remove and store in a safe place.



There is a start point set up, you will find it here in the green book:

https://1drv.ms/b/s!Ask6E_1jz4xIgYRg...Dnwzg?e=i5WFp5

It is a pretty simple instrument, just start at the beginning and work your way through. I'll leave the link up for a week or so - download a copy for yourself.

Good fortune,

Alan