I'm looking at rod bearings and the different sizes and wonder about the .001 size bearings. Are they for mtors that have some miles on them but have not been taken to .20 . This may be fairly obvious but I'm not real sure and wonder if I should be ordering that size for my motor??? Thanks
yes they make .001 and .002 bearrings for people who dont really need there crank turned.what you need to do is get some plastic gadge and cheak them.you need to find out what the standared size is sup.to be for your motor and go from there.also dont just cheak one!you need to cheak all of them.some might be standard and some might be alittle oversized.
I've used .001's and .002's lots of times on older engines that were just a little loose. Quickie ring-and-bearing jobs to get a driver back on the road quick. Nothing wrong with them as long as the crank isn't out of round.
First you should mike the crank and find the bearing clearance. You can then get the proper clearance bearing. The +.001 and -.001 are made to adjust clearance for application. Some builders prefer a +.001 for additional clearance for stroker motors for instance. If you have a STD crank journal and its "slightly" worn but consistent, you may want to close up the clearance by using a -.001 shell. Take the crank to a pro and let them recommend the correct bearing depending on what you have and the intended use.
Yes, if you do use plastigauge, it comes in green, red, and blue packaging, depending on the thickness. It is like dental floss, cut small strip, put in with rod bearing, or main bearing torque rod, or main down, take out, then size it up with the gauge on the side of the package. It flattens down, and you will then know what the gap clearance is, and go to the parts store, and buy the appropriate bearing-you probably will have to explain to the parts person, what plastigauge is though.
If they're available for your application I have it polished up on the journals (JUST polished) and go with the .002's.
I always measure each crank journal 4 places. I do the front and rear of the journal and then 90 degrees from there. This will tell you how O.O.R. it is. Then I take a rod, with the used bearings still in both halves, torque the bolts and measure the bore with a dial bore gage. I take 2 readings, close to the split as possible and inline with the rod beam. Any taper in the crank (along the centerline) more than .001, look to have the crank ground. Take the nominal average rod diameter reading - the nominal average crank reading (per journal)/2 = your clearance. As long as the crank doesn't have odd-ball bearings in it, (like someone reground 1 or more journals, I've seen it), go with something giving you the .002 clearance. Better off a little too much than too little in an old engine with a re-used crank. An old Motors Manual should give you the specs to back up your decision. If all checks out, polish up the journals with a light oil and crocus cloth. Bob
Hmmm, I have plastigage but I tossed all the old bearings when I dis***embled ( a rookie mistake I think ) so I'm not sure if I can make a decision on bearing size using a mic on the crank. If i can, where would I get crank specs for a 1977 351 Windsor ...Thanks again
Buy a factory service manual for whatever car has the particular engine you are screwing with. Most oem manuals will talk about this very subject. The manual will then also provide all of the remaining details about re***embly. .
you know that you can buy just one bearing.i have bought several extra bearings before to get the clearance all the some{some are alittle off}i would spend the couple bucks for a standard bearing +.001,and a +.002 if available.and cheack them all.when you find out which one or ones you need yous go to your local parts store and get them.
You might consider the cost of a grind v/all the related activities your contemplating. The max allowable taper/oor is .0005. While plastigage is useful on a fresh grind, it is not useful for checking oor/taper. Use mics.
For the shaft size specs. You can go to any "Real" auto parts store. In the Federal-Mogul, King or Clevite (Mahle) "BOOK", not on the computer. With every bearing is a housing dimension, shaft dimension, min and max specs. Most good stores will look this up for you. You must measure the shaft as the factory doesn't always go by the published specs. They try to use everything coming down the line and it isn't unusual to find an over/undersized bearing on one or more journals. ALWAYS read the bearng size from the backside of the bearing when dis***embling an engine!!
man, there really is a lot of good advice on this site and i appreciate the help. I think I am going to try using a mic on the crank as well as buying one new bearing in a couple of different sizes and using plastigage t omeasure them. I might as well use this as a learning experience as I go along ..thanks again.
No, I didn't so i took the crank and had it ground so I didn't have to wonder about what size bearings to use..
It has to do with crank wear and how round it is. More often than not an old original crank will clean up @ .010. Once in awhile you find a crank with some wear that is still round or all it needs is a good polishing to be right but then you will be out of tolerance and that is where a .001 or .002 under insert will come into play. Like Opel says you have to check all the journals and see where you are at. You also need to remember that it is not just clearance that you are ttying to hit but your journals also need to be round. Snag a mic and check all the journals if they are not round get it turned.
The Crankshaft is the Foundation Of The Engine. I often tell people "We wouldn't build a $500000.00 house on a Cinder Block Foundation". Then my next quote would be "Never enough time to do it right but always enough time to do it over". Grind the crank and install the correct bearings >>>>.
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