Holley Carburetor Jet Size Chart & Drill Size Guide
Holley Carburetor Jet Size Chart & Drill Size Guide
This guide provides a practical reference for Holley carburetor jet sizes and how they relate to common drill sizes used for cleaning, checking, and tuning work.
Holley Jet Size Chart (Approximate Drill Size Reference)
Holley jets are identified by number (such as #60, #70, etc.), which corresponds to fuel flow rather than exact hole diameter. However, these sizes closely align with standard drill sizes and are commonly referenced this way in real-world tuning.
| Jet Number | Approximate Size (Inches) |
|---|---|
| #40 | 0.040" |
| #50 | 0.049" |
| #55 | 0.052" |
| #60 | 0.057" |
| #65 | 0.063" |
| #70 | 0.070" |
| #75 | 0.076" |
| #80 | 0.093" |
| #85 | 0.096" |
| #90 | 0.101" |
| #95 | 0.104" |
| #100 | 0.128" |
Note: These values are approximate. Holley jet numbers are based on fuel flow, not exact diameter.
Using Drill Sizes for Carburetor Jet Work
Precision drill bits are commonly used in carburetor work for:
- Cleaning clogged or partially blocked jets
- Checking approximate jet size
- Carefully modifying jet orifices
Because drills come in fine size increments, they provide a practical way to work within jet size ranges.
Practical Drill Size Range for Holley Jets
The chart below shows a practical drill size range covering many commonly used Holley jet sizes from 0.040" to 0.125".
Click the image for easier viewing.
This range allows you to work across typical jetting sizes without needing to piece together individual drills.
Complete Drill Set Covering This Range
If you are working with Holley carburetors, having a complete range of sizes in one set is often more convenient than sourcing individual drills.
View 0.040"–0.125" Holley Carburetor Jet Drill Set
This 50-piece set includes solid carbide drills covering the full range shown above in an organized case for quick access.
Tips for Jet Sizing and Modification
- Use light pressure when working with carbide drills
- Always verify size before modifying a jet
- Make small, incremental changes when tuning
- Avoid enlarging jets unintentionally during cleaning
Conclusion
Understanding the relationship between jet sizes and drill sizes can make carburetor tuning more efficient and controlled. Use this guide as a practical reference and keep a full range of sizes available for best results.