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MG MGB Technical - exhaust leak???

Have a 1974 MGB (since 1984).
note: all of the emission control stuff seems to have
disappeared over the years.

have what I suspect is an exhaust leak. noticed a 'sputtering' at tail pipe at idle........holding sheet of paper to exhaust results in paper being sucked up to tail pipe.....very intermittently.

what could be causing this??????

fuel mixture too lean????
exhaust leak??? (had the exhaust system checked from
exhaust flange gaskets to tail pipe --- all tight).
valve adjustment???
timing???

THANX!!!!!!!!!!!!

L Rousselle

Any or all of the above plus some more!

Can't see it being an exhaust leak though, sounds more like a misfire. An irregular splashy misfire usually indicates weakness as far as mixture is concerned. However you should go through everything - valve clearances, plug, points, rotor, cap and lead condition. Check the condenser by seeing how far the spark will jump in free air (usually around 1/4" but watch out for shocks if you are holding a lead and drawing it away from the block for example). Check the dwell and timing, the latter with a timing light for missing flashes and both for jumping about. Then balance the carbs for air-flow and mixture from scratch.
PaulH Solihull

This thread was discussed on 10/09/2010

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