Don't be afraid to adjust the carb with more than just your idle-air screw! The opening line says it all, right? Install a new carb or one that you just found at a local swap meet and don't be afraid to turn some screws and change some jets. I've been to many automotive-related classes in the past, but always seem to forget the part on how to tune a carb.
Some can tune by sound and by vacuum, but I could never really tell if the truck got faster or slower without a dyno or dragstrip. Dyno shops are the next option, but unless you are interested in squeezing every last horsepower out of your engine then the cost for dyno time may not be in the budget.
So what is the next step for the at-home or even local hot rod shop builder when it comes to tuning carbs? Well for me I learned how to tune a carb by how well it ran, but that method only got me so far. I never knew how rich or lean the engine was running and was always timid about driving the vehicle hard.
This is why I turned to an O2 sensor and reader for tuning carbs. Most importantly I could now tune to a targeted air/fuel ratio instead of guessing or looking at spark plug readings. Did you know that running an engine too lean or too rich can cause major engine troubles? A while back I was at a friend's shop where he showed me the effects of an over-lean condition. To make a long story short the engine self-destructed. So here are a few tips that may help you tune your carb with a little help from a O2 sensor reader.