i just recently bought a 95 Z off my buddy. I was aware that it had an engine knock and the engine was just rebuilt...like only ran 20 minutes rebuilt. Oil pressure was always good(above 40 at idle and climbed when reved). Never revd high due to engine break in..it did lack power right off of initial start up, but we figured it was because he was running stock injectors with his hot cam setup, which had the ecm programmed for 30 lb.'s. Engine is completely stock except for hot cam kit. Just got the engine out last night and tore it apart. I have included pics. Before i took the crank out, i checked for end play. The crank did have end play with the rods off.(close to .010 play in and out) removed main bearings and could see brass starting to show on all of them including thrust bearing. Now my friend informed me that this machine shop that built the engine turned his crank .010 on the throws and mains, but what is catchy is that the crank my friend supplied was brand new. Im thinking the shop may have ripped him off and kept his crank and gave him a crank that was laying around..idk why they would, but its just a thought. The casting number was 14088528 which i have never seen. An LT1 crank is 14088526, correct? Even if it was an incorrectly balanced crank wouldnt it eat the mains before the rod bearings? Im just very puzzled as to why it spun a rod bearing(#1 rod). The bearings were all for .010. Oil was thinner and clearly had gas in it but i figured that was from the cyl. bore damage as you can see in the pics. which was probably caused by lack of oil psi and oil couldnt reach the walls. Piston skirts were clearly rubbing the walls. Any help would be great. Im taking the block to a trustworthy machine shop thursday to get the cyl bores and crank bores checked. I just dont want to put new internals back in and have it happen again. Thanks
http://s685.photobucket.com/albums/vv212/1993fast_z/

 

pictures are great....after posting these pics, i got to looking at the one showing the crank. these pics were taken before the mains were taken off. Note the main cap is on backwards. Could this cause a rod failure?

 

your link only shows two pics, neither of the mains. If a cap was installed backwards this would effect oiling and yes, it will cause bearing failure. Why isn't the shop that built this rebuilding it for free? They are clearly at fault if they put it together wrong.

 

if you move your cursor over to the scroll area, the toolbar will disappear and you can see the F and the the arrow. I called the machine shop and they are not standing behind the engine...Nobody deal with Jim Stenger in McConnellsburg Pa...he said that the invoice never stated any type of warranty, etc. **** poor service...

 

That rod Journal is JUNK!!!! There is no way that happened in 20 minutes of run time. I don't care what you do to it I have never seen a rod do that to one journal in that amount of time. I have seen them do that after driving for a long time and having a spun bearing. That crank is probably junk, unless you get one bearing that's going to be massively undersized. I'd start looking at getting a new crank and start from scratch. as for the cyl walls, a good hone should clean them up....they aren't that bad.....again JMO

BTW it doesn't look like there was any recent cyl wall work done.....It lookis like a high mileage motor cyl wall.....I think your buddy got bent over and straight f*cked

 

bad bearing clearances. caps mixed up.

 

Crank is definately junk, cyl walls were clearly honed.. A better pic would show.. Bearing clearance was .0025 according to invoice. I think spec is .0008 to .0022

 

It too has a spun rod bearing, but its yours intake to oilpan if you come take it out of my 97 TA.

 

Whoa, looks like my crank after we toasted it, yup that crank is junk no fixing it.

 

I'd bet, since it was #1, the problem was due to debris in the engine. The forward main journals are the last to have oil delivered and thus the #1 and #2 crank rods receive their oil last as well. When you have a spun bearing at the front of the engine, especially a fresh one, in most cases it is due to debris in the block restricting oil flow.

 

I was thinking the same thing, matt. I did check the pickup screen for any debris but there was none. Or just the simple fact that all the bearings were starting to wear and it then lost oil press. Making #1 the worst because it is last. The scoring in the bores got lighter and lighter the closer you get to the back of the engine, so def. No oil to the walls. What about the lack of power? It was like that from initial start to end of its short little life..Would stock 24 lb injectors with the hot cam kit cause that? That question should Prob should be a new post..

 

an .0025 clearance is not bad at all for an SBC. My previous 357 ran the same, and I was going to loosen it up to .0030 Loose clearance and thin oil is a good recipe for HP. As for the injectors causing this....I really don't think that would cause the bearing issue. It may be a reason for the washed walls a little. Aside from that, I'd say get a crank, and have the cyl. honed and put it back together......Personally I think it's a good reason to go 383, since you need the new crank.....JMO tho...

 

no go for the 383..i am currently in the process of putting one together right now for my 93 Z, this car is gonna get put back together and sold..i got a good deal on it, so hoping to make some profit..would anyone happen to know some part numbers for aftermarket cranks? cast steel..whatever is cheap. is the SCAT 910526 an lt1 crank?

 

Cylinder walls are lubricated by splash oiling, oil pressure has nothing to do with it. That cylinder wall scoring can be from several things, incorrect piston to wall clearance, detonation, dirty assembly, metal debris from that smoked rod journal, etc

We turn new cranks sometimes too - the cheap off-shore cranks are not sized correctly out of the box and need to be turned to fix the problem, so that is no proof of mis-doing on the shop's part.

Either little to no oil getting to the damaged areas, or the oil was severely thinned out with water or fuel, if the machine work was bad the rods could have been too large on the big end and had no crush on the bearing...but being a front to back problem I still think you had some oiling issue and if you truly had sufficient oil pressure then I don't know what to say without seeing the parts in person.

No matter what was said on the invoice about a warranty, that shop owners response is total BS. We will warranty all our motors except race motors, yours would not be considered a "race motor" and even on the race motor stuff if something were to go wrong we would take the motor back and tear it down to find out what the cause was.

Nothing can really be confirmed until knowing more... how complete the rebuild was - this wasn't a quickie job right? Why was their fuel in the oil, and how much? - it didn't come from the cylinder wall damage.

 

machine shop performed a shortblock rebuild, everything was new except pistons and rods. Heads were completely redone, etc. We put the heads and up on..nothing on the top-end was failed and there was no coolant in the oil, it was definately fuel..will know more thursday when i take the block and failed parts to a buddy of mine who has a machine shop. He wont let me leave without a truthful answer as to what happen. As far as the oiling to the walls, i was always under the understanding that a combination of the oil that squirted out past the rod bearings when the cyl was on the firing stroke and the slinging effect like you had mentioned is what lubricated it. its always good to learn something new. ill keep you guys updated and let you know what we find