Recipes @ altitude

[SundanceKid]

What effect does altitude have on a Q-Jet recipe? I live at 4400 feet. Other than jetting should I do anything different when modifying my carbs?     

[Cliff Ruggles]

This is something one has to experiement with.  First order of business is to make sure the carburetor is in perfect working order, then evaluate the performance and tune exactly for the altitude, if it is off some?

Typically about 1 jet number for 5000'.  Keep in mind many late model carburetors are lean right to start with, and may not need leaned up any further for high altitude use if they still have the factory calibrations in them?....Cliff

[SundanceKid]

Thanks for the reply Cliff.

Tinkering with Q-jets is a hobby of mine. Before I found your book three years ago, I went about it on my own for years. Instead of changing restriction sizes I would swap the body/throttle plate/air horn to accomplish the same thing.

I've never had any issues, but I'm always eager to learn more.

I have lots of questions, but I'm trying to pace myself.