You should have seen the ones that came out of the Regal after just 7 passes down the track. Mostly eaten away. what was left was paper thin and really ragged.
What were the bearing clearances set at, oil pressure hot, balance line/no balance line, max operating RPM, Oil type/viscosity, oiling system and pump, filter, oiling mods? Larry
bearing clearances were what are in factory service manual cant remember off hand, revved to 5800, 5-30 penzoil w stp additive for zinc, booster plate, stock pump and housing as they fell within spec per service manual, no oil mods, rotating assy wasnt balanced, but line bore was in spec
Hmmm, could be a culmination of things, being you don't know what the clearances were, and the 5/30 oil. Some bearings are toast some look "ok" Sloppy machining perhaps?
Correct me if I am wrong, but I am seing the bearingS from 4 Rods in your photo, no? Was the Crank cut to a under size? How did you check your clearances, mic, or plastigauge? Are these the original rod bolts that where used, if so how many times have they been torqued up? Are the imprints of the digits from the back side of the bearing smeared in the rod Bore, or main Bores , or are the clearly showing up? Did a chamfer get put due to deburring into the parting line of the Rods or mains , be they caps , rod big end or block? Did all the main cap bolts thread smoothly all the way into there holes with just light finger force ? Are the main bolts new or stock ? Are you using just a dummy oil light, or a gauge to read pressure? Overall I have to say it looks like a oiling issue, or grit in the oil and or passages to me, so where the oil passages in the Crank 100% clean and good to go?
When bearing clearances are not correct, the oil pressure at the rear of the block is not high enough. That starves the back of the engine and leads to bearing failure. If your bearing clearances were factory stock, you would have more consistent oil pressure, pressure does not bleed off to the rear of the block, at least not as much. http://www.v8buick.com/index.php?threads/oil-pump-clearances-and-oil-pressure.326597/
Classic BBB failure, seen it dozens of times, did the exact same thing to the BBB in my first car, over 30 years ago. The direct clutch in the TH 400 in my 73 Centurion began to fail gradually on the highway, so gradually that I simply did not notice that I was really into the throttle to try and maintain 60 mph... and of course being a teenager at the time, the radio was cranked, and I could not hear the poor old 455 screaming at the top of it's lungs, until the oil light flashed on, and killed the radio.. I took it apart, and it looked just like that. The two bearings that failed are the two that are the most likely to fail.. Number 4 main, and number 7 rod. Number 4 main is the most highly stressed main in the block, due to the external balance weight swinging around on the flexplate.. HD high rpm use, with a less than perfectly balanced rotating assembly can result in that main bearing damage. Oiling is factor here also, but more likely the crank/block are flexing enough to cause contact at the number 4 main. High mileage motors often have main bore alignment issue.. the size can be fine, but until you stick the hone in it, you have no idea of the alignment, which is actually more critical that the individual housing sizes. That's why the process is called "Align Honing". DO NOT SKIP THIS STEP IN YOUR NEW ENGINE. If your machinist says to you "they are within the size limit, and should be fine" let me translate that for you "I don't have the tooling to do this size main, so let's hope it's ok" Align honing is not an optional procedure. PERIOD. Now number 7, I saw in the other thread the argument about stock oiling systems being adequate for a stock build. I would tend to agree with that, but the statement is incomplete. "Stock oiling systems and oil clearances, are adequate for stock engines, or for stock rebuilds, when the engine is going to be used in light duty situations" Nearly 50 years ago, BMD Engineering produced a technical bulletin, whose name as I recall it was " Recommendations for 400/430/455 Engines for Heavy Duty usage" or words to that effect, it's been years since I last read it. The oiling system got two upgrades-- the HD White spring to boost the oil pressure to 60 PSI, and the recommendation to use the factory +1 bearing, to open up the rod bearing clearances, to promote more oil flow, to cool the bearings at high rpm. Number 7 rod bearing had "stock type" clearances, inadequate for HD usage, when you pressed it to 5800, it overheated that rod bearing, and the end result is what you see here. This shows up on number 7 first, because it is the farthest bearing from the oil source, that has to have the oil fed to it, against the G forces developed in the clockwise spinning crankshaft. Often we get caught up in oil pressure, when in fact, oil volume, and flowing oil across the bearings to remove the heat, is just as important as the pressure feeding it. You just have no gauge that shows you that, so folks don't think about it. How to prevent this?... Don't skip machining steps. Align Hone is a critical process, in regard to keeping the bottom end in it. Utilize HD oil clearances, at least .002/.002 mains and rods, I prefer .0025/.0025, with the appropriate passage modifications. I am often heard to say "Spend more money on your build, so you save money"... and no, I have not been exposed to too many fumes, that just another way of saying "Do it right, or do it over", and it's always more expensive to do 3/4 of the job twice, than all of it once.
I'd have to say, in light of all this, that taking it to 5800 was the borderline that might have been 'ok' for some, but not for others, which is why you often hear 5500 as being the 'redline' for stock oiling. I'd follow Jim's advice here, he's the pro on this stuff (as well as others too). Thanks everyone for all this great information.
I am often heard to say "Spend more money on your build, so you save money"... and no, I have not been exposed to too many fumes, that just another way of saying "Do it right, or do it over", and it's always more expensive to do 3/4 of the job twice, than all of it once Super good advice Jim!
It amazes me how some people will seemingly put an engine together in a sand storm with nothing but a 40 piece socket set and it runs forever... I learned a long time ago I'm not one of those fortunate sorts and when it comes to this hobby (at least with a Buick engine) it certainly is a buy once cry once type of life I lead.
Yep.. Took me a while to notice when I bought economy grade parts so much that I could have acquired a quality part/service twice over and been done. Build timelines are extended however there is much more time enjoying vs fixing. I apply this to all aspects of life, there is no overkill.
