MG Car Repair: stromberg carb piston position, accelerator cable, engine emissions

Question
QUESTION: Barrie,
 this should be an easy one.  there are 2 holes on the botom of my carb piston.  do I locate them on the engine side, on the air filter side, or straddle the carb?

thx

ANSWER: Hi Scott.  The holes transfer the vacuum from the engine to the top of the piston, causing it to rise.  Therefore they must be on the engine side of the piston.  

---------- FOLLOW-UP ----------

QUESTION: Barrie,
Car starts fine now.  Piston lifts up great.  But the engine races up to maximum speed and I need to turn off the car to get it to stop.  it appears that the butterfly(throttle) is in a fairly closed position.  is there an adjustment needed, is there some kind of bypass that is allowing all the air/fuel into the manifold? what are the common causes of this?

Answer
Hi Scott.  By adjusting the tickover screw you should be able to completely close the butterfly.  If it will not visibly shut, then something is keeping it open.  Could be a tight accelerator cable or a mis-aligned butterfly.  If it completely closes and the engine still races, then there is air getting in where it should not, for example the engine emissions pipe may have a split in it.