Wow! I never expected such a debate on what I thought was a simple question!
OK, let me explain what I am up to. I am trying to order replacement screws for my Zenith/Stromberg carburetor (so, Larry, you may stop worrying about me: it IS non-structural indeed). Now, the bottom part of the carb is secured with long, thin machine screws, which are of a diameter of roughly 3.2mm, if I remember well. Obviously, to order that, I needed to identify the screw size correctly (remember, I live in Europe, so non-Metric things must be ordered from the US by mail order, and the order must be right first time, otherwise...I'm screwed!). With metric screws, this would be a non-issue: take a caliper, measure the diameter in millimeters, period. But US machine screws seem to have obscure names, like MS35206-203, and even more obscure size names, like 2-56 or 8-32. So, I was definitely lost. And yes, before I asked, I did check in Tony Bingelis's books, and also the AC-4313 1A, even in the Jeppesen sheet metal course, and the Internet too. Lots of data on AN stuff, but I could not find any explanation on the machine screws measurement system. Now, I then noticed that the smallest AN bolt size is also defined the same way (10-32). Hence my question: what do the two figures mean, so that I can understand what is what in the Imperial system, and make sure I order the right stuff. I am now pretty sure the correct size will be 8-32. Thanks for all the help, guys. Now, for fellow non-US builders who are also lost in translation, I compiled a Microsoft Excel table of the AN hardware sizes which gives Metric measurements. Anybody interested, just shoot. Serge Vidal KR2 "Kilimanjaro Cloud" Paris, France
