How does a lean runup and Burbling sound?

[labawg]

Unless your Frank or Jerry or one the Sages, it is hard to determine what things sound like. A example; you do a hole shot and the motor sounds rough until 3000 rpm and then zoom. FJS (meaning Frank, Jerry and Sages) can listen and say "Thats burbling" meaning its way rich and getting too much fuel. The rest of us guess and normally wrong. I'm asking FJS to educate us on common motor sounds.

 

[Frank Acampora]

Re: How does a lean runup and Burbling sound?

Those are very difficult to describe, especially rich running. It's like when you hear a noise in your car and take it to the service shop.

Needles set too lean will sound on a hole shot like the engine will die from lack of fuel and indeed it is temporarily starving. It will start to accelerate well but quickly run lean on fuel. Then, when the main venturi starts delivering fuel, it will pick-up and run well. So, it "sags" then picks-up.

Now, too rich on a hole shot will sound like the engine is running rough but will not sound as if it will stall or die. It will not "cough" but rather it will "stumble." Then, as the engine needs more fuel at higher RPM and again the main venturi starts delivering fuel, it will clear itself, start to smooth out, and pick-up again.

Hope that helps a little.

If I could do video, I would demonstrate both conditions and once you hear it you will know.

 

[labawg]

Re: How does a lean runup and Burbling sound?

Thanks Frank, it does help. I kind of knew it was runing rich but the sounds are kind of hard to figure out some times. A video with seven speaker surround sound would be great!