OK, another engine building question

 LOU,Buy this book.

you are checking the total clearance of the bearing. the journal is supposed to be perfectally round so that is the available clearance at any given point. or at least that is how i understand it

You tube has some videos for visual aid. Normally check measurements in three places. Heres some good reading since so many on here give bad advice . Enjoy the link.

Edited by mlpankey - 26 Sep 2012 at 5:38pm

Here, a live link that works.
http://www.carcraft.com/techarticles/ccrp_1202_how_to_check_bearing_clearances/

http://www.circletrack.com/tipstricks/4636_crankshaft_rod_bearing_installation_tips/

Put her together the dirt and  grime should grind in the clerance just fine .

Lou, I built my 69 dodge dart here at home. Dirt floor basement is where I built my rearend and transmission. While it is nice to have a perfectly sanitary work environment and every tool known to man, sometimes ya just got to make do with what ya got.

That was my only car at the time. I drove it every day and raced it on the weekends for five years. Never had a problem with it. I did shear the bolts off of the ring gear once cause I was broke and decided to reuse the ring gear bolts when I changed gear ratios. That was a fun day.

injpumpEd wrote: LouSWPA wrote: ya know guys,a couple of years ago my neighbor asked me to "look" at his Ford 600 (I think it was), said it was making a noise. Well After listening, and using a stethoscope, I suspected the #1 rod bearing. I dropped the pan and sure enough, #1 rod bearing was pounded out. I said he would need to pull the engine and have the crank rebuilt. Well he didn't want to put the money into it, asked what his second option was, I said used engine. he asked what his third option was. I said polishing the crank by hand, and finding the bearing for the best fit and run it till it blows. he chose door number 3!!!! So, for two nights I lay under the tractor in the barn, in the cold, working down high spots with jewelers files and polishing the crank with fine emery cloth. Cleaned it up and had my lovely bride, who ran a NAPA store get me 10, 20 and 30 thousand over bearings (believe it or not she could get just one bearing!). I plastigaged and discovered 10 was just a little too tight, so I put the 20 in, torqued it down, closed up the patient and he ran that thing for a season and a half before it granaded! and boy, did it ever! So, articles that tell me that I need a climate controlled environmental and $10K worth of tools are sort of a waste on me I guess the point here is that it still failed... eventually! LOL!

Gerald J. wrote: If 10 was tight, 20 was an interference fit and had to be ground out to give clearance before any oil got to the clearance space, since its mostly the oil in the space that makes the sleeve bearing work. It works poorly dry, wears fast. If 10 was tight, you needed a 5 thousands undersize or to take off a couple more thousandths all around that journal keeping it round and with out flat spots. That's very hard to do with files, a strip of crocus cloth the width of the journal will come closer to keeping it round pulled back and forth with both hands, and regularly moving the crank to a different position. Gerald J.

Edited by LouSWPA - 27 Sep 2012 at 8:39pm

The crank pin usually wears out of round. Most wear on the compression stroke. Sometimes the pin wears as much as the bearing insert.

I've been around a few rod bearings myself. Back about 1961 I was mostly driving my dad's '54 ford 6, his first new car and that summer it had about 65,000 miles. He'd always had to rebuild car engines at about 35,000 mile intervals and was worried it was wearing and needed attention, so I rigged a hoist to the garage rafters and lifted that engine out and opened it up. Bearings plastigaged like new bearings, maybe .003" clearance, well within tolerances. But one rod bearing insert had a groove in it. Seems the oil hole drilled in the crank shaft was more like 3/8" than the typical 3/32" and the automatic deburring tool wasn't that big so the grinding had left a burr that got loose and cut the insert. I put in a new standard bearing, and reassembled the engine and put it back in the car and drove it to about 110,000 when I bought a new car. The new car, a '64 VW needed valve jobs so often I've forgotten how often, and at about 90,000 miles wrecked rod and mains from getting run too low on oil from a bad flywheel seal. I traded that engine for a '68 engine making that a hot running VW. After the second valve job on that bigger engine which included a big bore kit, I never did learn the top speed, because above 87 the front wheels were in the air from the lift over the body. I also moved the oil cooler out of the fan shroud and dropped the oil temperature significantly and that engine ran at least another 50,000 miles without being touched.

About that same year of the VW engine swap, I was on active duty (not a volunteer) and a buddy had a beetle, that developed a bad rod knock and with others helping he had taken it apart in the post craft shop to find the insert worn through with wear into the rod itself. He went shopping for a new rod and some parts guy told him they could repair that rod, didn't need a new one. And so they honed it. Had a nice new finish inside, but with new inserts and reassembled it still had a rod knock. One afternoon I helped him take it apart. He was practiced and I was too, we had engine out, tin removed, and crankcase apart with rod in hand in 45 minutes and during part of that time I helped another soldier drop engine and transmission from a Corvair. Dial calipers showed the "refurbished" rod was about .010" out of round. So he went hunting for a new rod. Journal seemed OK, but a new rod didn't completely fix the rod knock. I don't remember that he ever got the rod knock worked out of that engine. Probably the bad rod had done in the piston and it was slapping or maybe the original problem was a plugged oil passage in the crankshaft that we neglected to check.

In my dad's work bench front he bolted on an oak plank with various standard shaft diameter holes which he used to polish electric motor and other shafts using the strip of crocus cloth. He'd been a motor tester and repairman for some years. With a fairly snug fitting hole in a couple inches of wood a shaft would hold still under the down pressure from the crocus cloth, yet was easy to turn to make the polishing cut the shaft down round. He used that when he built a garden tractor and for auxiliaries used poured babbit bearings. Rather than ream the poured bearings or wear them free, he worked the shaft out and then worked its bearing surface down to give clearance.

Gerald J.