Good Air Fuel Ratio/carb tuning info

[Howard Jones]

Surfin catch, on carb AF ratio and engine performance.

Carburetor Tuning: The Air/Fuel Equation: Engine Builder

 

[Doug S.]

Good info!!

Gotta wonder why the Air Gap type manifold makes such a difference in carb choice???

Cheers from Doug!!!

 

[Ian Clark]

Thanks for posting, I learn something everyday Worth making a copy of, there is a print version provided too. Cheers

 

[Frank3]

Air gap manifolds keep the air/fuel charge cooler , and provide a large straiter individual shot into the combustion chamber . Providing less heat in the manifold means less fuel vaporization , and more chance of fuel condensing on the runner walls . Straighter larger runner means less turbulence , thus more chance for fuel to fall out of mixture . And pulse reversion knocking fuel out of the mixture .
Then add lots of overlap and duration to the cam and this is all multiplied !
But this is more of a low rpm issue .
At least thats my understanding of it .

 

[Frank3]

Oh , and I almost forgot , the cam and manifold combo would create a lower signal in the carburetor ( vacuum ) there fore less fuel would be drawn from the bowl leaving a leaner mixture .

 

[Seymour Snerd]

I converted it to a PDF and added in the pictures and captions at the end:

View attachment Carburetor Tuning -- the Air-Fuel Equation with figures.pdf

 

[John Fitzpatrick]

The March 2008 article on tuning distributors designed for leaded gas for the different gasoline formulations being sold today is an eye-opener too.
Old Iron: Tuning A Carbureted Engine: Engine Builder