Holley Drill Conversion Chart.

Holley Drill Conversion Chart.

Just because you know the diameter of the hole in the jet doesn't mean you should start drilling on Holley jets!
The same size hole can flow more or less depending on the tapered/ radiused edges leading into and out of Holley jets.
This drill size chart is here so you can use a drill set to figure out what all of those loose jets you have lying around are supposed to be.

NEVER STORE HOLLEY JETS ON A WIRE! The wire will expand and misshape the orifice!
Stringing them on Nylon fishing line is a much better idea, but a jet storage board is very cheap, and definitely the right way to store your extra jets.

**Number, Decimal, & Fractional**
Drill Number	Decimal Size	Fractional Size	Drill Number	Decimal Size	Fractional Size
80	0.0135		57	0.043
79	0.0145		56	0.0469	3/64
	0.0156	1/64		0.0469	3/64
78	0.016		55	0.052
77	0.018		54	0.055
76	0.02		53	0.0595
75	0.021			0.0625	1/16
74	0.0225		52	0.0635
73	0.024		51	0.067
72	0.025		50	0.07
71	0.026		49	0.073
70	0.028		48	0.076
69	0.0292			0.0781	5/64
68	0.031		47	0.0785
	0.0312	1/32	46	0.081
67	0.032		45	0.082
66	0.033		44	0.086
65	0.035		43	0.089
64	0.036		42	0.0935
63	0.037			0.0938	3/32
62	0.038		41	0.096
61	0.039		40	0.098
60	0.04		39	0.0995
59	0.041		38	0.1015
58	0.042