SYSTEM
OVERVIEW & TECHNICAL INFORMATION
“AN”
Thread Sizes
AN sizes, originally developed for use by the U.S.
Armed forces (“A” for army and “N”
for navy), describe the outside diameter (O.D.) of tubing
in 1/16-inch increments. For example, an AN 2 fitting
will fit a tube with an O.D. of 2/16”, or 1/8,
while an AN 8 fitting will fIt a tube with an O.D. of
8/16”, or 1/2”. Because the actual thickness
of tube walls can vary from brand to brand, the inside
diameter of a tube is not used as a reference. You will
also find the dash (-) symbol or the word “dash”
itself used in conjunction with AN sizes. A “dash
six” fitting translates to AN-6.
Each AN fitting has an established thread sizing. The
following chart shows the relationship between AN size,
tube O.D., and SAE thread size:
AN
Thread Comparison |
| -AN SIZE |
Metal Tube O.D. Inches |
Closest SAE Thread Size |
| -2 |
1/8” |
5/16-24 |
| -3 |
3/16” |
3/8-24 |
| -4 |
1/4” |
7/16-20 |
| -5 |
5/16” |
1/2-20 |
| -6 |
3/8” |
9/16-18 |
| -8 |
1/2” |
3/4-16 |
| -10 |
5/8” |
7/8-14 |
| -12 |
3/4” |
1-1/16-12 |
| -16 |
1” |
1-5/16-12 |
| -20 |
1-1/4" |
1-5/8-12 |
| -24 |
1-1/2" |
1-7/8-12 |
| -28 |
1-3/4" |
2-1/4-12 |
| -32 |
2" |
2-1/2-12 |
NPT
Thread Comparison |
| Pipe Thread Size |
Threads Per Inch |
App. Interior Diameter |
Closest AN Size |
| 1/16” |
27 |
1/16” |
2 |
| 1/8” |
27 |
1/8” |
4 |
| 1/4” |
18 |
1/4” |
6 |
| 3/8” |
18 |
3/8” |
8 |
| 1/2” |
14 |
1/2” |
10 |
| 3/4” |
14 |
3/4” |
12 |
| 1” |
11-1/2 |
1” |
16 |
| 1-1/4” |
11-1/2 |
1-1/4” |
20 |
| 1-1/2” |
11-1/2 |
1-1/2” |
24 |
| 2 |
11-1/2 |
2" |
32 |
| NOTE: A sealer is not required when
"AN" type fittings are used but is required
for "NPT." |
“NPT” Thread Sizes
NPT sizes (National Pipe Taper) are the most commonly
used fitting sizes
for general plumbing, piping, and tubing use; not quite
as popular as
AN for automotive use, but still very common. While
AN fittings depend
on the outside diameter of a tube for sizing, NPT fittings
depend on the
interior diameter (I.D.) of the fitting itself. The
following chart shows the
each size’s thread-per-inch count, the l.D. of
the fitting, and the AN fitting size with the closest-matching
l.D.(inside dimension).
Overview Of A Typical NOS System
| Item |
Description |
| 1. |
Bottle Valve Adapter |
| 2. |
Bottle Valve Washer |
| 3. |
Bottle Bracket(s) |
| 4. |
Nitrous Bottle |
| 5. |
Injector Plate |
| 6. |
Carburetor Stud(s) |
| 7. |
Carburetor Gasket(s) |
| 8. |
Nitrous Solenoid |
| 9. |
Fuel Solenoid |
| 10. |
Nitrous Filter Fitting |
| 11. |
Compression Fitting Adapter |
| 12. |
Solenoid Mounting Bracket |
| 13. |
Flare Jets |
| 14. |
Formed Nitrous Solenoid Extension Tube |
| 15. |
B-Nut (Tube Nut) |
| 16. |
Fuel Filter (in-line) |
| 17. |
Formed Fuel Solenoid Extension Tube |
| 18. |
B-Nut (Tube Nut) |
| 19. |
Main Nitrous Feed Line |
| 20. |
Fuel Hose |
| 21. |
Fuel Line Tee Fitting |
| 22. |
Fuel Hose Clamps |
| 23. |
Throttle Microswitch |
| 24. |
Toggle Switch (not shown) |
| 25. |
Universal Extension Tube |
NOTE: This is an NOS “Cheater” system for
a Halley 4-barrel carburetor application. In addition
to what is shown, the kit will contain electrical components
for activating the system.
|
