I have a few core carbs that I've used for "practice"; with reasonable success. Pretty much all my tubes show evidence of the punch being just a bit too small--it's like the punch sinks into the end of the tube, leaving a very thin ring at the top. I'm using a 3/32 punch.
Yanked out six idle tubes from junk carbs, then went to pull 'em out of my "good" carb.
Sure enough, when I try to extract the idle tubes on a carb I CARE about--I screw it up.
Pounded one tube too far in; the end is destroyed and the tube is bent.
SO:
How interchangeable are these tubes? I've got three pair of potential replacements; I can drill the hole in the bottom end to match--but they aren't all the same length. Does a small difference in length make a difference in the way they work? How "picky" are they in terms of getting the bottom end the right distance from the bottom of the hole they're installed in? Does it make a difference if they're at different depths left-to-right?
My first guess is that they aren't picky at all, minor length variations don't make any difference. But I'd like to hear that from you, rather than playing guessing games...
Press-fit is wonderful when you're putting stuff together nice 'n' new, in a clean factory. Man, does it suck to deal with it thirty years later. Maybe I should try popping idle tubes out with dynamite next time.