No such thing as a stupid question, RIGHT ? Suppose you needed .002 clearance on the bearing and it was only .001. Could you use a good hone to enlarge it ? To me, as long as it was smooth I think it would work . Your thoughts please . Learn me, teach me !
Getting it dead true straight is your challenge. By the time you do that it's probably cheaper to buy new bearings.
You really should look for a different bearing.....that being said of you really really had to use them you *might* be able to talk your local engine shop into using their rod hone on the offending bore to open it up. You'd (they'd) do this with the bearing in the rod and the cap torqued to spec. Sent from my SM-G950U using The H.A.M.B. mobile app
i'm curious....what engine? i think new standard bearings would leave you in the same spot you are. you can get get .001 and .002 undersize bearings for a small journal SBC https://www.summitracing.com/search/Part-Type/Rod-Bearings/Crankshaft-Undersize-in/0-001-in/ https://www.summitracing.com/search...ke/chevrolet/crankshaft-undersize-in/0-002-in once upon a time i tore apart a 283 sbc that had standard size main bearings on 4 of them , and one had .002 undersize. i don't believe the engine had ever been tore apart before me, so i assumed it was to cover a factory fuckup
Babbitt you maybe could, but not with a hone , being a stone it will leave traces of abrasives. Modern bearings, no , they are layered and some have coatings you’ll wipe. Buy the right bearings.assuming we’re talking crank bearings.
you could...it might not last long, or it might. hard to say. But a better idea would be to figure out why the clearance is what it is, and why you want the clearance you think it should be.
Squirrel... Your starting to sound like kung Fu .. that reply was only missing the trademark .. Grasshopper
Some engines will tolerate clearances...some wont.I took a part a 300 Ford 6cyl,and it was missing a main bearing insert.The man purchased the truck new,and it had never been apart.I know a guy who put a piece of oil soaked leather in place of babbit on a early inline 6 cyl,and drove it around town for a long time at low speeds.Most engines won"t live long with out getting noisy,or worse.
I got a set of bearings for a BBC and it says NOT to even scuff it with scotch-brite. It has something to do with holding the oil.
I always wondered how the “scuff the bearings” thing got started, it seemed so illogical. The manufacturers spend huge $$$ developing their best possible bearing and now some guy wants us to take an abrasive and some solvent to that micro thin overlay?
have just gone through this doing a 350 with my son standard clevite bearings only gave .0015 to .0017 i contacted clevite about bearings with an additional .001 and they told me the only bearings with the additional clearence were the narrowed ones their clearance recomendations were .0007 for each inch of journal diameter sbc at 2.10 is .00147so i guess we are ok
i used to polish bearings with very fine scotchbrite iread about it in an article by bob gliden he thought it gave the bearing better oil retension now i listen to the people who make them and just check the clearance and put them in
I have a '59 Continental 4 banger in my tractor with loader and drag box. Had a rod knock since I got it and last winter I finally pulled the pan. One rod bearing was spun but the journal looked OK, until I measured it. .010" (yes, ten thousandths) out of round. Pulling the crank requires busting the whole tractor apart, not worth it on the old horse. Put in a new bearing, some Lucas additive. Used it all 2018 and still going strong. Oil pressure gauge in the green, no audible knock, but I do keep the revs down and try not to work it too hard.
I grabbed the nearest factory shop manual....1964 Pontiac...it says under Specifications--V8 Engine: Connecting Rods--Bearing clearance on crank pin--limits when new: .0005" - .0025" Main Bearing clearance--Limits when new: .0005" - .0020" Just a little sanity check.
Factories in the past used "Select Fit" bearings, Electronicly measured the crank and a printed build sheet would tell the assembler which bearing to use, cheaper and quicker then flogging the crank.
You polish the rod journal on the crank. It is not real common to find one that the tolerance is to tight. Normally if you are going by the book you have a fairly large window to hit, like say .00X0-.00X9. In a standard lathe turning it slow it is easy enough to pick up a few tenths with a piece of emery cloth, with a little patience you should be able to pick up a thousandth. Or you could chuck it up in the crank lathe and knock a thousandth off real quick. I would not try to hone a Babbitt insert with a standard hone and drill. I may give it a shot with a Sunnon Hone (or reasonable facsimile there of). Around here if you know which shop or store to hit you can get inserts in undersizes of .0010-.0050 in increments of .0010 for most common engines if you are running a standard size crank. But that will not help you if your clearance is too tight. The best way to address that is to address the real problem.
Wait a minute... Squirrel looked up the clearances of the Pontiac engine, which seem pretty typical of "modern" V8 engines. The OP states his clearance is .0015 to .0017, or right in the typical specs. Where's the problem?
Reminds me of a guy I knew who purchased a old dozer at auction.They didn't allow testing.When he got it home it ran,but had no power.He pulled the head,and it had NO piston,or rod in one cylinder!
Clevite uses a x at the end of the part number to give a extra .001 clearance. .001 under is stated as well as std and .010 undersized. Depending on who you talk to behind the counter they may not be aware of this,a x bearing is only available in std diameters. Main and rod bearings. Hope this helps
Recheck you micrometer readings .001 is easy to miss if you aren't proficient in reading mic's ..when using internal mic's I usually measure 3-4 times ....worst bearings to measure are 30's Ford fully floating con rod..these need clearance both sides...very time consuming if you dont want bearing failure which Ive seen after 100 miles
A friend had a small block Ford crankshaft reground to -.010", but they took off too much material resulting in .003" clearance. The dealer had undersize bearings in .011" size, so he was able to restore the proper clearance. I don't recall if this was on the mains or rods.
The Jalopy Journal
