Thanks for all of the info guys-what would be the biggest bore I could go up to safely? I've been told 60 over?
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Sleeving 55 cylinders
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Originally posted by j**r**m View PostThanks for all of the info guys-what would be the biggest bore I could go up to safely? I've been told 60 over?
The individual casting must be measured to determine the remaining casting wall at the thinnest spot.
Some OEM 74" castings will take .100" overbore, and have a safe .070" remaining.
(Some oriental castings will hit daylight at .030" over!)
Great variation can occur beyond the original "core float", resulting from the additive errors of several bore jobs over the decades.
A skilled machinist can easily bias a boring bar away from the thinnest spot, hopefully back toward the true center.
And once again lest it be overlooked, the use of stress plates is manditory for excessive overbores. They should be applied for fitting any 74" cylinder at .060" or more over standard bore.
(And also applied to sleeved cylinders of any bore!)
....CottenAMCA #776
Dumpster Diver's Motto: Seek,... and Ye Shall Find!
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For what it is worth, Atlantic Machine in New Bedford Ma has the touch, and has even saved a few JD cylinders with sleeves.Dan Margolien
Yankee Chapter National Meet July 31/August 1 2020 at the TERRYVILLE Fairgounds, Terryville CT.
Www.yankeechapter.org
Pocketvalve@gmail.com
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Is anyone out there experts on hard chrome as is used in the aircraft industry? For years the aircraft industry has used chrome to build cyls back to standard. The famous Pratt&Whitney 1340 & 985's cyls which havn't been produced since approx 1953 have been rechromed countless times as surplus NOS parts are long gone. The crop dusters have been running these engines for years. Chrome is used in many other aircraft cyls as well. That said most acft cyls that I am aware of were bored only once to .010 or .015 OS, so I do not know if cyls cam be built up .070 or more. A friend/owner of an aircraft shop that I sometimes worked at once in my off seasons asked a acft cyl chroming company if the would build up his jugs for his 50 pan. They were not interested, but this was about 30 years ago. Harder times have befallen the aircraft industry recently and maybe ther might possibly be a firm out there more willing to take on MC cylinders to help keep their doors open. I would think there could be quite a demand for this service, at least for a while. Maybe someone out there has some connections? Cam
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George!
No two cylinders have been bored, re-bored, and re-bored again and again to the same concentricity within the casting. Error is added every time a bar is centered into it.
It is far safer to actually measure the remaining wall, as I suggested previously, than to gamble on conjecture or anecdotes.
....CottenAMCA #776
Dumpster Diver's Motto: Seek,... and Ye Shall Find!
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