Thu Feb 04, 2021 7:15 pm by cornbinder89
As a matter of running, I doubt anyone would notice the difference in how the engine runs with any of those jets. Where it would show is with a exhaust analyzer, may show in fuel economy and how much carbon ends up on the plugs.
Holley jets are the same for the 2300 and 4 bbls and the 190x 1 bbl. so a 63 jet for one will fit the others.
Years ago I played around with jetting on a 1920 1bbl, and found you had to make large changes to the jetting before you noticed a change in the drivability This is partly due to economizer or "power valve". When the engine runs lean, the power produced is lower and the throttle is opened more which drops the vacuum, which in turn opens the economizer, which adds more fuel and richens it back up.
For best economy, you would like to set it up on a dyno, where you can make a single change and see what it does under load.
Wet fuel height in the bowl will also effect mixture in a similar way that a change in jetting will.
My guess is that a 1901 with the leanest jet (#63) placed on the biggest engine (282) would still run very well.
More often than not, poor performance is ign or even valve timing issues but are blamed on carbs. I've seen worn timing chains (not an issue with IHC) make it almost impossible to get good running, but when it is replaced, the engine runs great with no carb changes.
I am very leary of jetting changes until all other factors are eliminated as a source of the problem.
Jetting is most noticeable at WOT/ high speed, that is when there is the greatest pressure differential across the jet. That is why, the best way to select a jet, is on a dyno, where it can be run at full load with an analyzer in the exhaust stream at the same time.