[Tongue Pirate]

I had a demon on my big block chev. The idle circut was very sensitive. If your turning your screws out 2.5 turns it may be too far. Are you speaking of the red disc on top of the vacuum secondaries diaphram? If so my carb was an 850 with the same, so if this is the case you may have a larger carb than you think. Mine was too large for my application & I got a smaller holley free from a friend. I would have bought another Demon. Great Carb!!!