Carb Main Jets

[Al Schober]

OK, here's an assortment of main jets. One on right (with the groove) is marked 19 and seems about .032 dia. Next is a 23, about .040. Finally, a 24, about .042.
Of the 3 donor carbs, one is an adjustable main jet. The other two just had the plug.
It seems I recall (from somewhere) that the 23 and 24 are the usual sizes for fixed main jets. But then, why would the odd man be smaller? I would have expected it to be bigger, then control things with the adjustable jet.
I have the capability to ream #19 out to .050, but thought I'd get some input from you experts before doing so. It's tough to put the metal back!

[Dave Neptune]

Oh boy a carb question

Al, I'm a bit of a carb nut and have done a lot of playing with jets over the years on my beastie. I too have seen jets all over the place as well as a few different air corrector jets. Rather than right a new novel here perhaps a side-bar contact for a bit of technical info. By the way have you encountered any of the "longer" jets in any of them?
I don't want to get anyone confused by the mysterious variations that amount to little from the factory and a lot from the rebuilders!!!!!

Dave Neptune

[romantic comedy]

I have seen jets filled with lead solder then drilled out again. Never did it myself.

[Dave Neptune]

Carb tinkering

Comedy, I have used the fill method many times however it is when I don't have the time to wait for a new jet and I am a reamer manufacturer by trade. You do need to be careful in doing so because if you replace with a jet the size you opened the jet up to the performance will vary a bit because the "LENGTH" of the orfice also plays a part in the metering. I often found that I needed the jet a size smaller than I opened it up to for that reason. The process does work well for "individual" applications.
The carb on our A-4's leaves a lot to be desired as it is just to big. Most of us are at max cruise before the throttle is a third of the way open, so the range we are metering is still influenced by the idle circuit.

Al, I have also had very good results by altering the float level which does influence the mid to lower power range which is where we work these beasties. Hopefully I will have time to get a bit sent to you today.

Dave Neptune

[tenders]

Still waiting for the Moyer fuel injection add-on kit to put all of this silliness to rest forever.

(Seriously, carburetion is a black art to me; I find this kind of discussion fascinating.)

I wonder if the propane conversion is as easy as one of these kits...several videos on YouTube suggest that it is that easy for a typical generator engine.

http://www.propane-generators.com/bi-fuel_kits.htm

[ndutton]

There was a recent thread on propane about a month ago, found here.

A bit off topic in this thread but I'm curious about the perceived advantage.