Robert Berning wrote:
>
> Ever since I bought my 1972 MGB it had a slight backfire when shifting with
> any slight load on the engine. In the time I have had my MGB, I have
> replace the manifold gaskets and exhaust(donut). Yesterday while drive I
> blew the manifold gaskets or exhaust(donut), no exhaust at the muffler and
> very loud. I am in the process of finding which one went, but this brings
> up a question of what is causing it. Talking to a non-MGB mechanic friend,
> he thought it was a restricted/blocked exhaust and the backfiring was from a
> leak into exhaust (air hitting the unburned fuel). With this does anyone
> have a suggestion of better gaskets or gaskets prep. The manifold gasket
> shouldn't be a problem but the donuts seem really cheap, are there any
> better one I could buy? Is there a way of checking the exhaust besides
> cutting it apart?
>
> Thank you,
Robert,
I don't remember where you are located, but if you have the full smog
equipment (ie smog pump, air rail, gulp valve, absorbtion canister, etc) you
might want to check the gulp valve membrane...if it is bad, then that will
cause backfiring...
good luck,
Steve Sanchez
"under the bonnett in a 'detuned' '77 'B"
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