Choke flap permanently open 1b

Hi,

I guess this has been posted about a million times but I really cannot find what I'm looking for and the haynes hasn't really given me much information.

I have a 1983 Mk1 1.5l with a Pierburg 1b carb. The choke flap is fully open when cold and for the life of me I cannot work out how to adjust it, I have tried the usual methods applied to the 2e carb as I had one on my old cabrio, but any adjustment that I can see doesn't move the flap.

The haynes gives this information but I am unsure which screw.

Choke valve gap

27 With the engine cold, fully open the throttle valve, then turn the fast idle cam and release the throttle valve so that the adjustment screw is positioned on the highest part of the cam.
28 Press the choke operating rod as far as possible towards the pull-down unit.
29 Using the shank of a twist drill, check that the distance from the choke valve to the carburettor wall is as specified. If not, adjust the screw behind the automatic choke.

Any help would be great.

Thanks,

Mike

I have had a look at this again today, I found that there is a sort of cam, it prevents the choke flap returning to closed but when the throttle is opened it allows the choke flap to return to a closed position. It worked as it should when fitting the air filter and ran well until i drove it and got to a junction, the engine pulsed in revs from 1500 - 900 - 1500..

Could there be a broken spring somewhere of something out of adjustment, i dont want to start fiddling with the settings if it is a broken spring as it appears to run well. Has anyone got any experience of this?

take the autochoke off the side, the choke flap spring is built into this

Do you mean the bimetallic strip/spring?

When I have taken the auto choke off there is the lever that controls the choke flap. Movement is very limited and only moves about 10mm, but if I pull the accelerator cable and then try it, the choke flap closes, then I can put it all back together and its working as it should, starts and ticks over fine, then it warms up, I stop the engine and I'm back to square one with the choke flap only moving 10mm.

does it have a pulldown unit? maybe this isnt adjusted right or is sticky, I'll have to dig out the mk1 haynes as the 1b doesnt sound the same as the 2e2 as I assumed…