MG Car Repair: Cold starts, dashpot, stromberg

Question
I have a '76 B that I recently reactivated after 10 years of outside storage.  I did a whole bunch of work to get it going, including rebuilding the Stromberg.  It's been running great for months now, except that cold starts are taking longer and longer.  I now have to spend about a minute, cranking several seconds at a time, before it catches.  Sometimes, once it starts, power at low RPMs is so weak it almost stalls.  Once it warms up a little, it runs great, and warm or hot starts are never a problem.  The only thing I can think of is that the choke isn't working.  I did rebuild that (about a year ago now), but I'm not sure how to establish whether it's working properly or not.  Or is there something else I should be looking at?

Thanks!

Answer
Hi Billy

Sounds like the automatic choke is not working.
This quite a complex unit, and checking it is not simple.
Basically, when cold, it should partially open the throttle
and richen the mixture.  You should be able to see if the
throttle is partially opened by looking at the engine idle
speed screw.  When cold, it should be off its stop.  

This diagram may help:

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28999

By the way, have you remembered to fill the dashpot with engine oil?