DietCoke

iTrader: (18)

You mean plastigage isn't a reliable means for putting together a performance engine?

kinglt-1

iTrader: (26)

+1

If I had to guess since I am not a builder, logic tells me the problem is a oiling issue due to a restriction somewhere in the pipeline. I second the idea of letting the machinist assemble the short block.

csmc711

iTrader: (4)

If your working on the loose side of the scale and not trying to be exact, I would not see any problem with it.

moespeeds

To clear up the plastigage thing, the machinist does all the machining and measuring, I do the assembly. I only used Pgage after the fact because we had some around the shop and were curious about the tolerance on the rods. IT WAS NOT USED TO MEASURE FOR ASSEMBLY. The machinist measured the rod clearance at .0026, and in doing some research it seems pgage can be off by .0010 and usually on the tight side. As for assembling the short block, this is my first car, but not my first rodeo. Under my belt I have countless Vtwin motorcycles, a boat, and a Lycoming airplane engine that is still flying for some 15 years now. The assembly process doesn't scare me at all, it's simple and I'm a thorough and patient mechanic. What I don't like is that I have to rely on a third party here for some of the machine work and the clearances. I have purchased a bore gage to check the machinist, and this time around I will clean the block myself as suggested. After speaking with Jeremy Schwanke, he believes it was an oiling issue, but said that even if the clearance was as low as .0015 it would be fine. We went over all of the oil line routing as he's very familiar with the ASA dry sump system we use, and everything is correct. We're thinking the engine ingested some junk, probably still floating in the block from the last bearing spin. The thrust bearing took a hit when the motor munched and I shoved the clutch in to the floor, we had not yet installed the clutch stop so basically the throwout tried to push the crank out of the block.

For the O2 sensor question, no we do not run O2 sensors, series rules require us to use an open loop fuel table for fuel injection. I am allowed to install a wideband.

So we're starting again, with a different block as this one is pretty much toast. I will have him hot tank the block (he did last time) and I will personally flush it 100 times as suggested! I purchased a balanced rotating assembly from Schwanke engines so we're starting with a new crank this time, and he will match the bearings (P). Thanks for all the help and suggestions.

70caminoman

I have heard most of the suggestions and believe that many of them could be right; foreign material, tight clearance, crap in the oil, ect. However, even though this may be dumb, but did you happen to make sure that the radius on the rod brg's matched up with the radius on the crank. King H-series brg's usually have a larger radius on one side to account for larger radius found on race style crankshafts. This is something that I always fear to death when assembling my motors. Maybe it doesnt matter on a stock crank but anything that has a larger radius on it will **** a motor for sure. each rod brg will have a slightly larger chamfer on one side and that side has to be lined up to the outside of the crank throw to match the radius. Even though there is no top or bottom half on rod brgs this has to be checked. I haven't heard anyone mention this and it's just food for thought.

moespeeds

I used Clevite LS1/SBC Rod Bearings CB663HN-10, they do have a top and bottom. For the crank I used King H racing bearings, as the crank had to be cut .020 unexpectedly, and King is local to me.

70caminoman

Well that blows that theory. Sorry to hear your troubles man. Something that should be simple. And to think that people replace brgs without even pulling the motor from underneath. It's sucks when you do it all right and it doesn't work out. Still, something was not perfectly round for that kind of heat to develop. whether rods, crank, brgs, ect.

BlwnLs1GTO

iTrader: (12)

Sorry I can't offer any theory as to what's going on, but I believe the problem lies in what others have said. (Specifically the rod that suffered from either Too tight of clearance or oil starvation)
There's vendors here with great reputations that put together a nice stout forged short block for under $2,500.
I'd strongly consider this if I were in your shoes.

Actually, I've been in a similar situation with my LS car and on the last go around, purchased new parts and a new block and started from scratch with STD. clearances.

Good luck

csmc711

iTrader: (4)

If your absolutely positive clearances were fine, then that bearing was not getting any oil. Nothing else it could be.

RockinWs6

Exactly, detonation had NOTHING to do with this failure.

A.R. Shale Targa

iTrader: (2)

I'm very curious as to what assembly prep was done to the main bolts...
oil on threads ?? E.P.L. (extreme pressure lubricant) under the head ??
AND how many times had they been torqued prior to this particular assembly ??
With the main bearing clearance of an aluminum block application needing to be in that .0012"-.0023" range due to expansion growth, it is imperative that the bolt prep and torqueing procedure repeat and measure within .0002" several times.
Then and only then should the main journals of the crank be ground with the proper clearances built into the machining procedure. This method prevents you from having to buy multiple packages of bearings and mixing and matching dozens of times to get the right numbers, thus ruining the bolts. I've found that even ARP bolts or studs will repeat more consistently when the black oxide coating is muriatic acid removed.
Lastly when studying those bearings...great pics by the way; the number four main cap does see the highest bearing load per in^2. Just behind the center one where the crank design is the weakest and has no balance counter weights, that set of # four bearings shows the crank acting like a banana (see the copper wear areas). I'm guessing the crank is cracked in that number four main rolled fillet area. As it began shreading that bearing, the schrapnel was pressure fed to that number six rod, causing friction, heat, and eventually obliterating it.
You'll notice on Gen V and Gen IV big block cranks as well as Lunati BBC stuff that the center of the crank has counter weights or wings. Same as the Callies BBC 572 GM piece. This adds strength to the shaft as well as minimizes deflection due to harmonics. I always run a top notch balancer on my small block builds to help with those higher order harmonics that will crack **** and eat/murder perfectly good engines. Very sorry for your loss sir

Tony @ Mamo Motorsports

What oil pump where you running??

To get 50 PSI with a stock pump (at a hot idle) tells me the clearances were too tight. Some of the other rod bearings pictured were clearly tight as you can see by the defined line of the bearing surface messed up to where the bearing "footballs" more (widens at the parting line) and it looks untouched (due to the crank journal not being able to touch it there where the clearance opens up).

I would almost bet this engine didn't spin freely as it should when it was just a rotating assy installed in the block

This is not a detonation issue....that piston is pristine. Its an assembly error / clearance issue IMO

My suggestion is to have the shop assemble it next time with a promise if it eats another bearing that they deal with the repair.

Good luck sorting it all out

-Tony

RockinWs6

Honestly I'd move on to another machine shop. For someone to stand there and claim detonation without ANY evidence of it speaks LOUDLY. I'm talking from years of experience. I think it was put together too tight, this causes poor oil flow across the bearings and they overheat quickly. Another thing is number 1 rod bearing is the last thing in the engine to get oil....................

moespeeds

I bought a bore gage and measured the tolerances myself. .0024 on the rods and .0020 on the mains. That's well within spec. All bolts were brand new, OEM on the mains and ARP 2000 on the rods. Pressure lube was used on the rod bolts and main bolts. I've never heard of a machinist or builder that will offer any kind of warranty on an engine going into a non-production race car, but if someone knows a shop I'd love the contact info. I'd like to hear more about the #4 bearing. We were trying to figure out if that came before or after the rod failed? Why does the #5 rod look ok, or does this not get oil from the #4 main?

BTW the machinist cut the crank after we had the main bearings in hand, and he cut it to the tolerances I spec'd, which were given to me by LG Motorsports.

I asked around locally pretty much everyone I know for a new machinist, and I'm not joking, every lead came back to the guy I'm using. He has an impeccable reputation, but I agree with you guys, I just don't believe the detonation theory.

moespeeds

One more thing, look at the thrust face on the center main bearing, how badly worn it is. We did not have a clutch stop installed yet, but I was extremely careful in using the clutch. This car has a T101 clutch assisted trans, which means you only use the clutch to get the car rolling from a stop, then you don't touch it again until you stop again. It shifts up and down with no clutch. When the motor blew I stomped on the clutch as I initially thought I lost the rear. Think I could have done that much damage with one stomp, or maybe I was pushing it in too far all along, causing wear and sending debris into the rest of the bearings? Looks like it got munched pretty badly.