Holley four-barrel carburetors are probably the most common high performance fuel mixing devices on the planet. Given the sheer numbers of carburetors made since the 1950s, you know they work. If there is a fly in the Holley ointment, it’s setting up the idle. Since Holleys are so easy to adjust, it’s also easy to adjust them totally wrong. People will get the idle settings wrong, then blame the carburetor when it doesn’t work properly. That’s a big mistake.
Youtube Holley Idle Transfer Slots Free
In reality, setting the basic idle on a Holley isn’t difficult. We’ll show you how to do it on both vacuum secondary and double pumper models. What works on this pair of carburetors will work on your high performance Holley, too.
We’ll take you through the entire process in the slide show below:
Holley Idle Transfer Slots
What is the transfer slot, please? It refers to adjusting the primary throttle blades (idle speed screw) to expose no more than.025'.030' of the idle transfer slots. They're located under the primary throttle blades - must remove carburetor to measure with wire. At this time, the primary throttle blades can be closed, which tends to enhance the sensitivity of the idle mixture control. Most carburetors will have the butterflies adjusted with a small length (approximately 0.020-inch – appearing as a square) of the idle transfer slot visible below the bottom edge of the butterflies.