What is a gastro bar?

How are chainsaw pitch and bar size / type related? What is chain gauge? 7-tooth vs 8-tooth?

• I have two original Homelite EZ's (from 1957/1958; not the newer models) that I'm currently working on. They were $40 and they were only missing their starter covers, so I figured it was a good deal. Well, I didn't research the saws, then I come to find out they run 7/16" pitch sprockets. I also found out that 7/16" pitch chain isn't sold anymore. Alright, fun so far. One saw had the original 7/16" pitch sprocket, chain, and bar; the other had only the 7/16" sprocket. So, I ordered and installed an Oregon PowerMate .404 pitch 7-tooth rim sprocket. This is where I need some help. I have no bar and no chain for the .404 saw. I don't have much experience with chainsaws, so these are questions I would like to know about: Can any size chain pitch be used on any bar as long as the length of the chain is equal to bar length? e.g. can 3/8" pitch chain and .404 pitch chain be run off the same bar if they're the same length? The 7-tooth sprocket is also advertised in an 8-tooth sprocket. Does the difference in teeth on the sprocket make a difference on the saw, the chain I can use, the bar, or all of the above? Do I have to be selective in the chain that I buy? Can bars from different saws be used on a Homelite - especially an older model - or will this create issues with the oiler? Because some bars have rollers and others are hardnose, does this make a difference when running a chain on it? Is there still somewhere that sells 7/16" pitch chain, and if so, where? And the last thing I don't know: what is chain gauge (.050, .058, .063, etc) and does it effect what type / size of bar I can use? Thanks for any and all help - it's very much appreciated.

• Answer:

  Check this out, it will answer some of your questions. http://www.ereplacementparts.com/article/1507/Chainsaw_Chain_Measurements_Sizes_and_Types.html