MG Car Repair: MGB engine struggle after switch off the ignition, significant influence, camshaft

Question
Hello Barrie,
Finally I have finished my engine which works nice with good compression (180 PSI) on each cylinder.
The engine works fine with reserve power. I can say that your help was very useful and you have significant influence on engine repair.Thank you.

The one thing which makes me worry is that the engine struggle after switch off the ignition.
When I switch off ignition the engine is choking around 4 second. The ignition timing is setup correctly base on Piper 285 camshaft instruction.
I had NGK BPR6ES sparks and changed it into BPR5ES but it doesn’t solve a problem. What to do to eliminate this problem.
Best regards,
Mariusz


Answer
Hi Mariusz

BPR5ES plugs will be worse than BPR6ES. I usually recommend Bosch W6DP but you can use NGK BP7EVX.  Avoid plugs with an R in them.

The tickover must be set slow.  Try to get the engine to tick over at 800 rpm.  

If you still have the original SU carburetters and they have a spring-loaded valve fitted to each butterfly, then change the butterflies for plain ones, as fitted to the early MGB (WZX1323).

If all this fails, you will have to fit an anti-run-on valve.  These are available for the MGB.