Quote:
Originally Posted by Bob Nottingham
In going from C12 or C14 to C25, how much larger jet is usally required in a holley 750 or similar sized carb. It seems about 2 sizes may be in the range, any throughs or comments appreciated. Thanks Bob
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When changing fuels, the general rule of thumb is to change one jet size for every .10 change in specific gravity ( Fuel Density).
For instance,
switching from a fuel SG of .720 to a fuel of .725 SG wouldn't require a change in jetting.
switching from a fuel SG of .720 to a fuel of .730 would require a change of 1 size in jetting.
And switching to oxygenated fuels will usually require up to four jet sizes higher to start.
Start out easy and let the plugs ( read all of them, not just a couple ) be your guide for further changes.