MGB: underhood exhaust leak

I have a '79 B; fired her up last night to let her idle and get warm for a cool-night drive. As I walked over to my other car, I heard the B's idle speed slowly decrease. Thinking it odd, I opened the hood and a bunch of smoke/exhaust poured out.

Where/how should I begin my search, any suggestions? Thanks.

Since the idle dropped and then you had a bunch of smoke, I'd be more concerned with the possiblity of a stuck float or some such that increased the fuel in the firing chamber. Then figure that the triangle gasket by the cat blew through.

I forgot to mention, once I opened the hood and allowed the exhaust to escape, the engine idle returned to normal.

Poor thing just fouled its own nest.

LOL, but you're right. Any help on trying to track down the problem?

Buehler? Buehler?

Anyone?

Anyone?

[quote=callpaul]

...Buehler? Buehler? ...
[/quote]

It's his day off

Exhaust flange gaskets are very pron to leak age and rich running carburetor can burn them out. When the engine is cool jack up the left side use a safety stand and try to tighten up the six nuts usually they will vibrate loose. A firm turn will do treat the nuts to some PB blaster before working with them. If tightening up the flanges does not work you will need to replace them not a fun job with the engine in but doable..:)

Oh assuming you have converted over to a weber or SU...? If not you might not need to jack up the B..?

If it takes your car warming up to have the problem then it's most likely the intake/exhaust gasket. If it's always there then it's either the gasket or the rings on the exhaust pipe themselves. I'd test the bolts on the exhaust manifold first to see if you just need to tighten them, then the bolts on the exhaust pipe. If all else fails a new exhaust manifold and the exhaust rings are only maybe $20 so it may be worth it to replace both just to make sure.