backfiring!

[john nepper jr.]

After I installed my new Alcoa's & tires I put on 1,500 miles going up
to northern Minnesota. I have several questions that I'd like advise on
before I take action.

1) I have an unusual louder noise comming from the drivers window. It
sounds like an exhaust gasket is going/gone.

2) I have a VERY loud backfire every 20-30 minutes of 75 mph driving.

Could these 2 problems be related?

What else could be causing my backfiring problem?

Thanks,
John '76 Plam Beach

 

[thomas g. warner]

Sounds like you may have a bad connection or bad coil leads in the HEI
ignition. cinnabar wrote an article about it some time ago. check the coil
leads for fraying or loose connections.

As for the exhaust leak if you have the original manifolds I would get a Mr.
Gasket #453 and seal it on both side with permatex copper high temp silicon.

>After I installed my new Alcoa's & tires I put on 1,500 miles going up
>to northern Minnesota. I have several questions that I'd like advise on
>before I take action.
>
>1) I have an unusual louder noise comming from the drivers window. It
>sounds like an exhaust gasket is going/gone.
>
>2) I have a VERY loud backfire every 20-30 minutes of 75 mph driving.
>
>Could these 2 problems be related?
>
>What else could be causing my backfiring problem?
>
>Thanks,
>John '76 Plam Beach
>
>