How to properly drill carb jets?

yellow rose said
Don't drill them. Drills are about as accurate as measuring you cylinder bore with a ruler.

If you are going to modify an existing jet, you need a reamer. Drill the jet to ~.010 under the size you want and ream it to finish. Only run the reamer through the hole forward, and use only one pass.

brian6pac said
I believe it's the length and the diam of the hole not just the diameter.

They radius the hole on the inlet and outlet to blend it when they make the jets, it's nearly impossible to duplicate that at home in our garage... Best practice is not to drill jets, but buy the proper size from Holley...

Holley rates the jets after the hole is drilled and blended according to how it flows, not the hole size...