Guest ohollmen Posted November 13, 2003 Share Posted November 13, 2003 What is maximum allowable offset in piston pin axis direction for rod small (upper) end from the piston centerline when everything (crank, bearings, rods, pistons) is assembled ? In other words - offset would mean that the rod small end is located closer to one of the piston pin bosses than the other. Any figures available ? Is such deviation (likely resulting in uneven bearing loads in both upper and lower end of rod)more serious with fully floating piston pins (different figures from pressed pin setup) ? I'd really appreciate any insight from you gurus out there ! Olli Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 13, 2003 Share Posted November 13, 2003 This is controlled by the width of the crank journal and the widths of the rods. About 18 -24 thou is a pretty common clearance there, but some engines use a lot more, as much as 50 or 60, with no problems. In my experience, increased wear caused by any offset loading is negligible. John Quote Link to comment Share on other sites More sharing options...
Guest ohollmen Posted November 13, 2003 Share Posted November 13, 2003 This is controlled by the width of the crank journal and the widths of the rods. About 18 -24 thou is a pretty common clearance there' date=' but some engines use a lot more, as much as 50 or 60, with no problems. In my experience, increased wear caused by any offset loading is negligible. John[/quote'] Thanks for answering John ! However I'm not sure if you answered question about rod side clearances which in my case measured at 0.020 and seem to fit the range given by you. The case that I'm asking about is really hard to explain in even thousand words, so maybe an image will do better. Anyways in my case the offset is no more up to crank and rods precision and tolerances, but the the bore seems to be skewed somehow. The image probably asks the question even without words The crank and rods are new units so they should not have anything to do with the suspicious scene (Scat 9000 3.75", Scat I beam with 7/16 bolts). I hope the bore is offset rather than tilted (better out of two). Quote Link to comment Share on other sites More sharing options...
jt1 Posted November 13, 2003 Share Posted November 13, 2003 Lot's of times the rods aren't perfectly centered between the pin bosses, but that's more than I'm used to seeing. Are the big ends of the rods the same on both sides? I'm not familiar with scats, but some have a different surface on each side. Maybe that's causing the offset? John Quote Link to comment Share on other sites More sharing options...
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