I have a newer side hung holley 600 carb that I have had for some years but barely used.Bought it new. I used it in a race car for motor break-in and a few passes at the track using race gas. Changed the carb to the one need for the race car.dumped the gas out of the 600 put in the box and back on the shelf. It sat there for about two years. Now I have a use for it on my f350 and started using it, Had what seemed like a flooding problem intermittently from the beginning. The flooding was on the primary side. adjusted the float down some, no change. Changed the power valve, no change. Ok only one other thing to do. Pulled the bowl off for the third time to change the float, pulled the float, looked in my stash of carb parts and found a white plastic float with a helper spring. The Nitrophyl had no helper spring. Put the white plastic float in with the helper spring. cranked the truck ran fine no flooding , drove truck some ran fine adjusted the the idle mix everything's great. The very next day cranked the truck flooding problem again. This time the secondary's Changed the float. the nitrophyl float had a helper spring this time???? What gives with these nitrophyl floats?

 

ethanol

 

No kidding. That crap eats carbs that don't have upgraded seals and plastics if it sits for any length of time.