How to rejet a carb. the right way

[Anonymous]

When rejetting a carb, how do you know what size jets to change to? This is a general question - no specific carb. in mind. What signs do you look for to let you know that it needs to be richer or leaner? Are there any tools/gauges to do this?

 

[xctasy]

Very, very easy on Holleys. Power is proportional to jet area, and if you line up all the valid primary and/or secondary jet areas and venturi sizes against the actual net installed power, then things come out close. This technique is called benchmarking, or using known valid carby jetting to estimate new kinds. It's not a black art.

The best way is an air/fuel meter in the exhast, and dyno time with a set of varing jets.

Ford new exactly what they were doing with there carbs, and some have not replaceable jets,clever dudes!. The Ford Six performance guys can point you to the right combo in most cases.

http://falconperformance.sundog.net/default.asp

There is no such thing as a perfect, straight out of the box calibartion without a dyno. There are about 30 variables to balance, and it's just not practical to guess what jet will work. But you can get very, very close.