HOTRODS & CLASSICS

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TAP & DRILL SIZES

N.F. (SAE)
TAP SIZE

N.C. (U.S.S.)
THREADS PER INCH

DRILL
SIZE

1/4

28

NO. 3

5/16

24

I

3/8

24

Q

7/16

20

25/64

1/2

20

29/64

9/16

18

33/64

5/8

18

37/64

11/16

16

5/8

3/4

16

11/16

7/8

14

13/16

1

14

15/16

N.C. (U.S.S.)
TAP SIZE

THREADS
PER INCH

DRILL
SIZE

1/4

20

NO. 7

5/16

18

F

3/8

16

5/16

7/16

14

U

1/2

13

27/64

9/16

12

31/64

5/8

11

17/32

11/16

11

19/32

3/4

10

21/32

13/16

10

23/32

7/8

9

49/64

15/16

9

53/64

8

7/8

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