[endel]

OK, so after a few years of no problems whatsoever, I now have a big backfiring problem. 2L with Dellortos. Something changed and I don't know what. I have tried adjusting the idle mix screws, but it doesn't seem to make a difference. The car runs fine.... but the pop, pop, pop is getting old.

 

[Alfajay]

OK, so after a few years of no problems whatsoever, I now have a big backfiring problem. 2L with Dellortos. Something changed and I don't know what. I have tried adjusting the idle mix screws, but it doesn't seem to make a difference. The car runs fine.... but the pop, pop, pop is getting old.

I'm just guessing here, but...might a cracked flex mount be letting in air, so that when your throttle plates are closed, air is still getting into the combustion chambers, causing the backfire? I suggest this since you say that the problem started after things worked well for years - carb mounts do dry out and crack with age.

 

[endel]

That's what I am thinking. and will check/replace them all later this spring.