John,
I had a backfiring problem which (when I *finally* located it) was
totally caused by an air leak in the exhaust manifold. Before I found it
I had exploded several holes in the header tubes. I removed header,
welded like crazy for several hours, put everything back with plenty of
high temp gasket-in-a-tube and *ta-dum* everything was as quiet as a mouse.
Dwade No-more-backfires-now Reinsch
Longview, TX
79 B
78 B
79 B
On 26 Sep 1996, John Hed wrote:
> Subject: Time:06:01
> OFFICE MEMO Backfiring! Date:9/26/96
>
> Hi all! I was hoping for a little quick advice from all you experienced folk
> out there to (hopefully) get me in the right direction on a problem I've never
> dealt with before.
>
> I just bought a 71 MGB (couldn't resist the price) in average daily driver
> shape. The first problem I have to tackle is that it backfires! On almost
> every normal shift, I'll get a little backfire during the shift. If I
> deliberatly try and shift VERY fast, I can avoid the backfire a lot of the
> time. I checked and reset the static timing with no change. The PO had
> installed a brand new vacuum unit on the distributor and the hose to the
> manifold looks good. Should I check it dynamically with a timing light?
>
> I removed the two middle spark plugs and the #2 plug (front carb) looked
> perfect, but the #3 plug was black, indicating too rich a mixture on the back
> carb. Could a problem with the back carb (too rich a setting or flooding due
> to bad needle valve) be causing the backfire? I plan on removing the carbs
> and overhauling them anyway. Any other ideas are greatly appreciated.
>
> John Hed
> <John_Hed@WSSAGW.chinalake.navy.mil>
> 71 MGB..... new daily driver
> 71 MGB-GT..... nicely restored and weekly driver
> 58 MGA...... in parts awaiting restoration
>
>
>
>
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