Technical Your Carburetor Is A Computer

So says Uncle Tony on YouTube. Hadn't thought of it that way before, but I think I understand what he's saying. A lot of variable information is input to the carb and it interprets that info and makes the necessary changes to its output.

I need to watch some more of Uncle Tony's videos. And if you don't already own a vacuum gauge, go getcha one!

 

IF one thinks of the carburetor as a computer, then the computer program is engine vacuum.

Jon

 

Not sure I agree. The engine vacuum (static low pressure in the intake) is just a result of the engine trying to ingest air while something restricts the supply. The actual flow past whatever openings that let the fuel in cause the dynamic low pressure that brings in the fuel. The carb function is built around air speed, not the pressure.

The jets, needles etc. is the programming, they decide how much fuel to add to the air under different circumstances.

 

I just installed a vintage SW "Motor Minder" in my Plymouth. I didn't realize how much I missed having a vacuum gauge while driving.

 

I have one in my o/t '91 fox car and also a factory installed one in my 2019 Ford... Plus the Craftsman version in my tool box.. I never "fine tune" a carb without one...

 

For what it's worth, an AFR (air fuel ratio) gauge is MUCH more informative for tuning than a vacuum gauge.
And...so goes the computer !

Mike

 

Unfortunately also much more expensive. But with the cost of fuel these days you could save more than the AFR gauge cost even if you only use it to tune one daily driver over time.
Anyway. I like measuring things. Gives you repeatable facts to base adjustments on, not just "It feels a bit better now, I'll try adjusting it a bit more the same way to see if it keeps getting better." Basic, cheap gauges (or simply a stop watch) can help you a lot, more advanced equipment can help you even more -****uming you know how to use it.

 

If vacuum is the software, or program, then that leaves us with what to consider as the hardware.

I'd lean toward thinking of the carb's individual circuits as the hardware. The needle and seat and float to control fuel supply. The choke circuit for cold starting with its various air valves, rods, levers, and fast idle cam. The idle circuit for smooth, low speed operation with air bleeds and threaded needle valves for easy external adjustments. The accelerator pump circuit to provide a quick shot of extra fuel when opening the throttle above idle speeds. The main fuel circuit to supply the proper mixture at steady cruising speeds. The power enrichment circuit to provide additional fuel for accelerating, pulling up a grade or hauling a trailer or other additional load.

In many cases these circuits depend on vacuum to supply their input information to the carb. And vacuum is also required to deliver various, correct air/fuel mixtures to different places in the carb under different operating conditions. And in some instances these demands are supplied by plain old mechanical levers and rods and plungers and valves that are unaffected by vacuum.

Carburetors can appear to be these mysterious, crude, Rube Goldberg kind of inventions. But I'm still amazed that, for the most part, they work as well as they do.