Basically what your saying is that as the bearing caps (both rods and mains) are tightened the amount of torque required to turn the crank with just one tight should increase that same amount as each of the others are tightened. As good of an idea as it may be to turn the engine over after each component is installed to insure that there are no clearance issues that are locking it down it"s no way to know whether the bearing clearances, etc are right, if for no other reason than it would require throwing the torque specs out the window for nearly every, if not all of, the engine mfg. in existance. The mfg comes up with the torque specs for the bolts for a reason, to keep them from loosening while the engine is in operation. If you don"t tighten the bolt to the proper torque you stand more chance of engine damage from a lose bolt than you do from having a bearing "too tight" in the way you describe. Giving a "set torque" for the bolts and not for the bearing its self is one one reason that every bearing has a range of allowable clearance, and yes, those clearances are going to effect the torque required to rotate a shaft within that bearing. Think about it this way if you had one bearing with maximum allowable clearance that took say 7 inlb of torque to roll the shaft over and another with minimum clearance that took say 14 inlbs to to get it to turn then based on what your saying the engine isn"t going to run properly even though the mfg says it is within their tested tollerances to do so. Given the allowable plus and minus specs needed in just about every part made due to imperfect manufacturing processes it"s not at all unreasonable to think that, whether it happenes every time or not, eventually parts of minumum amd maximum tollerances are going to get mixed. Over the course of my life I"ve seen it happen many times, often with no problems, but just as often it causes fit up problems and I"ve had to trade off one piece or the other to make the assembly work.
On top of that you also have to look at the friction of the rings on the walls of the cylinder as they are also going to add to the force required to turn the crank. Whether we admit or not no two rings are guaranteed to be identical. Given that fact if one was a little more sprung than another it"s going show a little more torque needed to turn the crank than the other one would. In this case the torque difference isn"t even in the bearings and is, in reality, a factor that the engine builder has no control over.
As far as the bearing clearances there are some engines that have to have the parts machined to match the bearings and if they don"t then your out of luck. At the same time there are also engines that are designed with tight clearances and you have to shim the caps to get all of the clearances within the given specs.
Whatever type of engine someone might happen to have if it doesn"t turn when assembled then it"s guaranteed something is wrong. Now whether it"s a ultra tight bearing, or something as simple as a fastener that was too long used somewhere and rubbing against an internal part is hard to say. Either way the only thing to do is to start dissaembling the engine and trying to turn it at each step until such time as the problem is found. To that all I can say is Good Luck.
We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today. [ About Us ]
Today's Featured Article - A Belt Pulley? Really Doing Something? - by Chris Pratt. Belt Pulleys! Most of us conjure up a picture of a massive thresher with a wide belt lazily arching to a tractor 35 feet away throwing a cloud of dust, straw and grain, and while nostalgic, not too practical a method of using our tractors. While this may have been the bread and butter of the belt work in the past (since this is what made the money on many farms), the smaller tasks may have been and still can be its real claim to fame. The thresher would bring in the harvest (and income) once a y
... [Read Article]
Latest Ad:
1964 I-H 140 tractor with cultivators and sidedresser. Starts and runs good. Asking 2650. CALL RON AT 502-319-1952
[More Ads]
All Rights Reserved. Reproduction of any part of this website, including design and content, without written permission is strictly prohibited. Trade Marks and Trade Names contained and used in this Website are those of others, and are used in this Website in a descriptive sense to refer to the products of others. Use of this Web site constitutes acceptance of our User Agreement and Privacy Policy
TRADEMARK DISCLAIMER: Tradenames and Trademarks referred to within Yesterday's Tractor Co. products and within the Yesterday's Tractor Co. websites are the property of their respective trademark holders. None of these trademark holders are affiliated with Yesterday's Tractor Co., our products, or our website nor are we sponsored by them. John Deere and its logos are the registered trademarks of the John Deere Corporation. Agco, Agco Allis, White, Massey Ferguson and their logos are the registered trademarks of AGCO Corporation. Case, Case-IH, Farmall, International Harvester, New Holland and their logos are registered trademarks of CNH Global N.V.
