MG Car Repair: crankcase breather pipe

Question
When I connect crankcase breather pipe to zenith carb 175cd w/auto choke at crankcase ventilation tube engine stalls. Help

Answer
Hi Robert.  

This should not happen.  Please advise me if you have changed ANYTHING on the engine.  I always suspect things that have been changed.  For example, on this model you should have a SEALED oil filler cap, whereas most MGBs have a vented cap.

It sounds as though you have a blockage somewhere.

The carburetter is normally set up rich, so that the small amount of emissions gasses will weaken it to the correct level.  Try undoing the oil filler cap and repeat the test.  If the engine no longer stalls, then it could be that the restrictor is blocked.  There is a restrictor built into the pipe that exits the rear of the rocker cover and goes to the absorption canister.  It may only need the restrictor clearing with a piece of wire, or it may be that the carbon canister is blocked and needs replacing.

The entire emissions system was never a good idea, so if the laws in your state allow you to do so, I would take it all off and put twin SUs on instead.  Better fuel consumption, 30 percent more power, and no more problems like this one.