What is the proper gas: air ratio

fastfarmall · Oct 23, 2015

Just curious what would the proper gas:air ratio be on the engines of the 60's? Isn't it like 15 to 1.

robgIN · Oct 23, 2015

pretty close , 14.7 to 1

leon · Oct 23, 2015

I think maybe the number given by robgIN is about right. You can also find a pretty good dissertation about stoichiometric mix on wikipdedia.

https://en.wikipedia.org/wiki/Air%E2%80%93fuel_ratio

Allan in NE · Oct 23, 2015

You nailed it, my friend!

Allan

Juicybusa2 · Oct 23, 2015

In theory 14.7-1 but in practice that number is typically too lean. I run real time data logging on my normally aspirated motorcycle and supercharged boat engines and both need a richer mixture to prevent detonation and to make max power. There are so many variables to consider that any general number thrown out there is almost worse than a guess lol . Timing, boost, compression, cam timing, octane,rpm combustion chamber design etc.

Joe Mindy · Oct 23, 2015

14.7 to 1 is the stoichiometric ratio for emission standards. If an engine is leaner like 15 to 1, then carbon monoxide and hydrocarbons will go down. However, lean mixtures cause nitrous oxides to go up. Consequently, 14.7 to 1 is the optimum mixture to minimize these three pollutants. However, 14.7 to 1 is not a good power producing mixture. When the engine is accelerating or under load, the throttle position sensor and mass air flow or manifold air pressure sensor will notify the computer that the vehicle is under load and the mixture will temporarily be richened. At idle or cruise the oxygen sensor will return the vehicle to the stoichiometric mixture. Old pre-emission cars of the 1960's will be richer than the stoichiometric mixture. This is the reason that computers were installed on cars beginning with the 1981 model year.

fastfarmall · Oct 23, 2015

Hay, you guys are good! Thanks

Old-F20 · Oct 23, 2015

I tune my old tractors to what the spark plugs tell me to........

David G · Oct 23, 2015

14.7 stoichiometric for gasoline, 13.1 max torque, 12.5 safe torque. An engine can be leaned out to 15s at light load and high RPMs. Each hydrocarbon has a unique stoichiometric number where all Hydrogens, Carbons and Oxygen are converted to H20 and CO2.

CenTex Farmall · Oct 23, 2015

What is the proper gas: air ratio

fastfarmall

Well-known Member

robgIN

Member

leon

Well-known Member

Allan in NE

Well-known Member

Juicybusa2

Member

Joe Mindy

Member

fastfarmall

Well-known Member

Old-F20

Member

David G

Well-known Member

CenTex Farmall

Well-known Member

Similar threads