I didn't notice the year of your MG, but do suggest that if you have smog
equipment (i.e..: the air pump and gulp valve, etc.) you consider disconnecting
or removing same; a bad gulp valve can cause some pretty violent backfiring on
trailing throttle.
Jim
Ajhsys@aol.com wrote:
> In a message dated 11/23/99 7:50:17 AM Eastern Standard Time,
> rswatson@nyx.net writes:
>
> << My poor little B is backfiring up through the carb. Starts up OK and
> drives around, but when I try to give it some throttle and get up to speed
> it start spitting back at me. I can't get the revs up much past 2900 under
> load. This problem came on rather suddenly after having been driven to
> work on our first cold snowy day. >>
>
> - - - - - - - - - - - - - - - - - - - - -
>
> This is often an indication of a burned exhaust valve. Do a compression
> test, or better yet, a leakdown test, and see if a cylinder is low. If the
> exhaust valve isn't closed all the way, the combustion can come back into the
> carb. Hopefully it is only an exhaust valve that is set too tight. Adjust
> the valve lash before pulling the head.
>
> (I hope somebody else has better news!)
>
> Allen Hefner
> SCCA Philly Region Rally Steward
> '77 Midget
> '92 Mitsubishi Expo LRV Sport
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