MG Car Repair: Backfiring, spark plug wires, backyard mechanic

Question
Hi Howard,

I am a new MGB owner / backyard mechanic.  My 1978 MGB backfires on the release from the throttle.  To address this problem, I have looked at the distributor and adjusted the timing, checked the compression (all about 110), adjusted the tappets to .013 (warm) and made sure all was well in the ignition.  

I do get a bit of a "bite" from the ignition / spark plug wires, do you think this may be why I get the backfiring?

Any ideas on what to do to fix the problem?  I haven't taken apart the carb, but if I need to I will.  

Thanks for any advice you could give.  I am very much looking forward to getting this MGB in tip-top shape.  

Regards,

Bradford

Answer
Hi Bradford,
Your compression is low, are you sure you held the throttle open when you did the test and did you let the engine spin over at least 4 or 5 times?
If the timing is correct and it seems to run ok, I would look for an exhaust leak either at the exhaust manifold (noted for cracking) or manifold to pipe connection or even a hole in the pipe before the muffler.
let me know,
Howard