Too lean?

[kozelding]

I have a Falcon stainless steel exhaust on my BT7, which I think is fairly high-flow (at least it sounds loud, for better or worse).

The car drove fine, but on hot days, it was running rich enough that the exhaust fumes (especially sitting at a light) would kill you.

So I leaned out the mixture a tad, which improved hot idle, but now I get exhaust crackles and pops on deceleration (which I never had before).

Now on the scale of "Hey, the tuning's finally right!" to "Crap, I'm running dangerously lean!" what are the little backfires indicating?

 

[TimK]

When my exhaust started backfiring on deceleration, it was because the exhaust manifold gaskets needed replacing and the brass nuts needed tightening -- air was getting into the exhaust downstream and allowing the unburned exhaust gasoline to ignite.

 

[bob hughes]

I can echo Tim on this one, same thing happened to me, in my case the nuts were a tad loose for some reason. You can try tightening up the nuts insitu as it were without removing the carbs and see if there is any slack, can be a bit tricky.

As to the lean - check your spark plugs, they should be white - a light grey if you are lean, - then watch out for burnt valves a nut brown is nice. I am constantly being told that they Healeys run better when a tad on the rich side though so a darker shade of brown would be the best.



Bob