UK Car Repair: MGB Stromberg 175 Carb/choke, moss motors, heat coil

Question
I have a 1977 MGB and am having trouble with the choke on the Stromberg 175 Carb. I have backed the heat coil back as far as it will go but fuel is so rich it kills the engine. You probaly know the choke is a water heated choke. I broke the small plunger on the bottom of the choke assy that holds the fast idle cam at different stages.  The plunger is moved by a lever connected to the throttle, which enters the bottom of the choke and pushes the plunger up to the fast idle cam, inside the heat mass. I feel there is something else wrong and I should be able to disable the choke altogether.  Can you help

Answer
Let me begin by saying, many suppliers make a conversion kit to return it to a manual choke. The piece you broke off only affects the idle, The actual choke plate is in behind the heat mass, the assembly has to be disassembled to get to the orifice plate, you can then figure out how to reposition the plate so that the fuel enrichment system is blocked, But, what are you going to do when winter comes?  The parts are available from Burlem, Moss motors etc to repair it properly.