Exhaust Backfiring

AJ/FormS said

So exactly under what circumstance is this"backfire" happening.
WOT, idle, 30mph/high gear,accelerating,closed throttle decelerating, tip-in,roll on in first, when you slam the pedal down, etc.
So remind me; when was the last time it ran great. And why don't you start there?
Was it just before you changed the bushing and regapped the plugs? Italmost obviously wasn't the filter......

Click to expand...

It was after moving the filter. I did find a flake of something on the passenger side needle. Cleaned it. Checked the float levels. Put it back on the car. Drove it 70 miles to Detroit ran OK. Then it started doing the same things. ??? So I took the Edelbrock off and put the Demon on. It always ran rich but never backfired. Do have MagniFlow mufflers on it now and they have a glass rapping in them that might soak up in burnt gas more than the Flow Masters I have on the car last time the Demon was on the car. Guess the question should be how can I lean out the Demon? I replaced the stock Metering blocks with the QF's to have versatility.