In this video, RacingJunk contributor Wayne Scraba walks you through setting and fine-tuning the floats on a common Holley carburetor.
To begin with, set your carb in a safe area with good ventilation and something to catch any fuel which exits the float bowl. Check to see if your floats are center or side hung.
Preparation depends on what kind of fuel pump you’ve got, as these are usually set wet. If your pump is electric, just turn it on, let it run and rock the fender of the car before checking the fuel level in the float. For a mechanical pump, you’ll want to let the engine idle until it stabilizes, then turn it off prior to removing the sight plug from the primary side of the carb.
If your fuel level is about right, it should just trickle out of the sight plug. To adjust it, loosen the lock screw, then turn the nut to lower or raise it. Once it’s set, simply retighten the lock screw. You can repeat the process on the secondary side of the carb. Once you’re done, reinstall both sight plugs.
Beyond the basics of setting the floats, Wayne also shows you how to fine-tune them to compensate for a car that’s running rich or lean. You can do this for both the primary and secondary sides of the carb.
If your car is running rich, drop the fuel level a tiny bit lower than the standard level; if it’s running lean, raise the fuel level. Don’t go too far, though. If your fuel level is too high, it’ll spill, while setting it too low can lead to your engine running out of fuel while under demand.
Make sure to check out Wayne’s quick-and-easy tutorial in the video below! He doesn’t just tell you, but shows you how to set the floats to perfection.