MG Car Repair: MGB Idle Screw, mechanic, screw

Question
Hello. I have a fairly simple question. I have a 1978 Mgb which I replaced the engine about 10 years ago to a 1972 twin carb (which is MUCH better). Anyway, I ran it two years ago and it was running great. I mistakenly took it in to my mechanic (not too knowledgeable about that type of car) for a tune up and now it idles to low and stalls and approaches overheating. I know all I need to do is adjust the idle screw, but I can't find it. I knew where it was on the old engine. Do you have a photo or something that can show me which screw I should be adjusting?

Thank you.

Answer
Hi Julia.  On the earlier twin carburetters the mixture adjuster is a large nut underneath the body of each unit.  You drop the nut down to richen, or up to weaken.  Sounds to me that the mechanic has weakened it too much.  See part #19 in the following exploded diagram:

http://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=28995

Get back to me if you need more advice on tuning these carburetters.