Hudson cars operating regularly at altitudes of 4,000 feet or more above sea level can often be improved performance-wise with leaner that standard metering rods and advanced ignition timing.
Use standard metering rods from seat level to 4,000'
Use one size lean metering rods from 4,000 to 8,000'
Use two sizes lean from 8,000 to 12,000'
Use three sizes lean at altitudes of 12,000' and above
| Car Model | Carb Number | Standard | One Size Lean | Two Sizes Lean | Three Sizes Lean |
|---|---|---|---|---|---|
| 1C & 2C Single | 2009S | 75-864 | 75-907 | 75-908 | 75-909 |
| 1C & 2C Single | 2009SA | 75-914 | 75-920 | 75-921 | 75-922 |
| 1C & 2C Twin | 2013S | 75-878 | 75-904 | 75-905 | 75-906 |
| 4C Single | 749S | 75-704 | 75-712 | 75-713 | 75-714 |
| 5C & 7C Single | 776S | 75-754 | 75-732 | 75-741 | 75-742 |
| 5C Twin | 990S | 75-851 | 75-856 | 75-857 | 75-858 |
| 7C Twin | 968S | 75-834 | 75-861 | 75-862 | 75-863 |