Carter Carburetor Jet Size Chart & Drill Size Guide
This guide provides a practical reference for Carter carburetor jet sizes and drill sizes commonly used for cleaning, checking, and careful tuning work. Carter carburetors include several different families, so this guide should be used as a practical drill-size reference rather than a guaranteed manufacturer specification.
About Carter Carburetors
Carter carburetors were widely used in automotive, classic car, muscle car, restoration, marine, and performance applications. Common Carter carburetor families include AFB, AVS, WCFB, YF, BBD, and related models.
Carter tuning can involve more than just changing a jet opening. On many Carter AFB and AVS-style carburetors, the jet works together with a metering rod, and the jet-and-rod combination affects fuel metering. Always verify the specific Carter carburetor model, jet type, metering rod combination, and application before cleaning, checking, or modifying a jet.
Which Drill Set Is Right for Carter Jet Work?
For Carter carburetor jet checking, cleaning, and careful sizing work, choose a drill set based on the jet range and carburetor type you expect to work with.
Best Starting Point for Many Carter Automotive Jets: HS1 50 Pc Carburetor Jet Drill Set
Covers a broad .040" through .125" range, which is useful for many larger automotive carburetor jet sizes, including common Carter AFB, AVS, and related jet work.
Working on Smaller Carburetor Jets?
The 20 Pc Selected Sizes Carburetor Jet Drill Set covers selected sizes from .0135" through .071", useful for smaller carburetor jet work, small engines, motorcycles, scooters, and similar applications.
Need More Continuous Numbered-Drill Coverage?
The 25 Pc #75–#51 Carburetor Jet Drill Set gives a broader numbered-drill range for general carburetor jet checking, cleaning, and careful tuning.
Want Backup Drills in Each Size?
The D7 50-piece #80–#56 set includes 25 sizes with two drills per size, useful when working with small, brittle carbide drills and smaller jet ranges.
Not Sure Which Range You Need?
If you work on several carburetor brands, smaller jets, larger jets, Holley-style ranges, Rochester/Quadrajet applications, Carter AFB/AVS applications, or Ford Model A Zenith carburetors, compare the full collection before ordering.
Important: carbide drills are brittle precision tools. Use light pressure, keep the drill straight, and avoid enlarging jets unintentionally during cleaning.
Carter Jet Size Chart & Drill Size Reference
Many Carter jet sizes are identified by stamped numbers or practical size references. These numbers are often used for tuning and comparison, but they should not be treated as guaranteed drill-diameter specifications. Actual fuel flow can vary depending on jet design, metering rod combination, entry shape, exit shape, finish, and condition.
The Nearest Drill Size Reference column shows the closest practical drill size or drill range for comparison. It is meant for checking and reference only; always verify the actual carburetor model, jet, and metering rod combination before modifying anything.
| Jet Reference Size | Approx. Inches | Nearest Drill Size Reference |
|---|---|---|
| 65 | 0.065" | 1.65 mm range |
| 67 | 0.067" | #51 range |
| 69 | 0.069" | 1.75 mm range |
| 70 | 0.070" | 1.80 mm range |
| 71 | 0.071" | 1.80 mm range |
| 73 | 0.073" | 1.85 mm range |
| 75 | 0.075" | 1.90 mm range |
| 77 | 0.077" | 1.95 mm range |
| 79 | 0.079" | 2.00 mm range |
| 80 | 0.080" | 2.00 mm range |
| 90 | 0.090" | 2.30 mm range |
| 95 | 0.095" | 2.40 mm range |
| 98 | 0.098" | 2.50 mm range |
| 101 | 0.101" | 2.55 mm range |
| 104 | 0.104" | 2.65 mm range |
| 107 | 0.107" | 2.70 mm range |
| 110 | 0.110" | 2.80 mm range |
| 113 | 0.113" | 2.85 mm range |
Note: This chart is an approximate drill-size reference. Carter jet sizing should always be verified against the specific carburetor, jet, and metering rod combination before modification.
Using Drill Sizes for Carter Carburetor Jet Work
Precision drill bits are commonly used in carburetor work for cleaning clogged jets, checking approximate jet size, comparing jet openings to known drill diameters, and carefully modifying jet orifices when tuning requires it.
Because drills come in fine size increments, they provide a practical way to work within carburetor jet size ranges. When modifying jets, make small changes and verify results carefully. For many Carter AFB and AVS-style carburetors, also consider how the metering rod interacts with the jet before making permanent changes.
Practical Drill Size Range for Carter Jets
Many Carter-style automotive main jets fall into larger small-drill ranges than the very small jets used in some motorcycle, scooter, RC, and small-engine carburetors. For this reason, the HS1 .040"–.125" range may be a better starting point for many Carter AFB, AVS, WCFB, and related automotive jet applications.
Smaller selected-size sets may still be useful for other carburetor work, checking smaller passages, or working on mixed carburetor types. If you are unsure which set is best, compare the carburetor jet drill sets before ordering.
Tips for Jet Sizing and Modification
- Use light pressure when working with carbide drills
- Keep the drill straight to avoid making the jet opening oblong
- Always verify size before modifying a jet
- Consider the jet and metering rod combination when working on Carter AFB/AVS-style carburetors
- Make small, incremental changes when tuning
- Avoid enlarging jets unintentionally during cleaning
- When in doubt, replace the jet rather than over-drilling it
Conclusion
Understanding the relationship between Carter jet references and practical drill sizes can make carburetor cleaning, checking, and careful tuning more controlled. Use this chart as an approximate drill-size guide, verify the exact drill size before modifying any jet, and choose the drill set that best matches the range of sizes you need.