[Modified Street Mustang]

Trying to figure out what caused this. SBC wiped out the bearings. Looks as if it started with the #3 main, and worked towards either end. It doesn't look to me like it was an oiling problem, because nothing really got hot except the #3 lower main. I done everything I know to do, and have always done when I put this thing together. I would just like to come up with an explanation before I start putting it back together. This is a mild 383 street engine that doesn't see over 5000 rpm. Was a brand new eagle rotating assembly. This thing also had a very serious blow-by issue that I can't seem to find the cause of either. Engine only had about 5000 miles on it, and it used about a quart of oil every 1000 miles. Is fuel injected with vortec heads. Had pcv as well. Pay attention to the second ring....I'm told that it is supposed to be a tapered ring, but just a fraction of the ring touches the cylinder wall. I was suspecting that this was the cause of the blow-by, but like I said, I was told otherwise.

 

[Slow 69 SS]

I assume the oil looked like metal flake paint. If you don't think it was an oiling problem, then the oil must have been contaminated enough to scuff everything up?

 

[youngengines]

What were your bearing clearances?

 

[revolutionary]

That is the way the rings are supposed to look. That is NOT how the bearings are supposed to look. Bearing clearance? Dirt? pickup tube?

 

[Modified Street Mustang]

Pickup tube is clean with no debris, bearing clearance was about .002 rod and main according to plasti gauge. Was using 10w30 motor oil.

So, if that is indeed how these rings are supposed to look, I wonder if maybe the machine shop put the wrong finish on the cylinder walls, causing the blow by.

 

[Modified Street Mustang]

Now, I believe the rod bearings were damaged due to debris (bearing material) coming off the main bearings. If for some reason debris ran through the mains, wiping them out, why would it destroy #3, and progressively get better as it moved toward the outsides of the block? Also, why would it only destroy the cap side of the bearings, and not the block side?

 

[Scott Smith]

Looks to me like it didn't have enough clearance so it made it's own.

 

[l88427]

looks like the oil was full of gasoline to me !

Trying to figure out what caused this. SBC wiped out the bearings. Looks as if it started with the #3 main, and worked towards either end. It doesn't look to me like it was an oiling problem, because nothing really got hot except the #3 lower main. I done everything I know to do, and have always done when I put this thing together. I would just like to come up with an explanation before I start putting it back together. This is a mild 383 street engine that doesn't see over 5000 rpm. Was a brand new eagle rotating assembly. This thing also had a very serious blow-by issue that I can't seem to find the cause of either. Engine only had about 5000 miles on it, and it used about a quart of oil every 1000 miles. Is fuel injected with vortec heads. Had pcv as well. Pay attention to the second ring....I'm told that it is supposed to be a tapered ring, but just a fraction of the ring touches the cylinder wall. I was suspecting that this was the cause of the blow-by, but like I said, I was told otherwise.

 

[satansracer]

If you say it started at number 3, I would guess if you check the alignment of your mains, your going to find a problem. First number 3 starts going, shoving metal into the oil and it is pretty much a downward spiral from there. Get it align honed.

 

[CNC BLOCKS]

It looks like alot of debris went right to your bearings from not having the oil filter bypass plugged and not using a good filter and the machine shop that did your work may not have cleaned the oil galleys properly.

By the looks of the blowby the piston shows blow by right down to the oil ring which is probably caused by not using a torque plate when the block was finished honed. A leak down test at TDC would confirmed your ring seal issue.

A link on plate honing
http://www.camaros.net/forums/showthread.php?t=58964

I noticed also that the main caps show no signs of a line hone which I feel is a must when building a performance engines.

A link on blue printing a block
http://www.chevelles.com/forums/showthread.php?t=93124


Under the drivers side head near the top of the block there are some blocks with a press in plug in that area, There are a lot of shops out there that don't take the time to remove that plug to properly clean the oil galley, There is no way to clean that galley unless that pug is removed.

We are now going through this same issue with a Covette engine as the customer was complaining of dirty oil in less then 100 miles and we leaked it down to find up to 35% leak down at TDC but the average was 18% But the customer did a compression test and it was 170 to 200 pounds.

We also found on the main bearings that there was copper showing near the sides of the pating lines as the block was never line honed during the rebuild.

We build a lot of circle track and strip and street engines and we never see issues like this and we have a lot of guys assemble their own engines as we fit their bearings for them and at the end of a season everything looks fine.

Here is a pic of the plug I was talking about

 

[greeze]

X2 Dirt&debrie It`s all embedded into the rod bearings, it looks like the crank wasn`t cleaned prior to start up..an area many forget to clean is the crank journals, rifle brush every passage in the crank and block before assembling. I`d ask for my money back on that bore job too, Pistons and lands look like my BBQ pit

:-kill

 

[Bammer540]

X2 on the fuel in oil. Your first clue is alot of blow by. Any time an engine has alot of blow by it fills the crank case with fuel, what you are seeing is very common when you don't torque plate hone a high performance motor.

 

[T-flow]

Sorry to see that, not good. Good Luck, T

 

[Modified Street Mustang]

The block is in the machine shop getting align bored as we speak. That was one of my suspicions after pulling it apart, but when I originally assembled it, the crankshaft spun free in the block, with no resistance, so it really didn't strike me as needing an align bore. The block was also honed with torque plates as well.

 

[CNC BLOCKS]

The block is in the machine shop getting align bored as we speak. That was one of my suspicions after pulling it apart, but when I originally assembled it, the crankshaft spun free in the block, with no resistance, so it really didn't strike me as needing an align bore. The block was also honed with torque plates as well.

Did they know what your were using for hardware and gasket as they plays a big part in the end result.

With the amount of blowby the pistons are showing I would question the plate hone.

Hopefully the shop is you a good hone to the finish hone with

 

[Modified Street Mustang]

Did they know what your were using for hardware and gasket as they plays a big part in the end result.

With the amount of blowby the pistons are showing I would question the plate hone.

Hopefully the shop is you a good hone to the finish hone with

I took is somewhere else, so maybe I can get some different results this time around, if that was the problem.

 

[Scott Smith]

Bolts or studs?
It's very hard to get a 400 to seal well with bolts.
Whats the bore?

 

[Modified Street Mustang]

Used gm performance factory replacement bolts. It's a 350 block, 4.030 bore.

 

[Scott Smith]

My bad. I thought it was a 400 block.

 

[Collinsautomotive]

Did anyone rifle brush the crank ?? the blow by isn't surprising with all the metal in the oil. I'd bet the bores look very worn out from debris acting like sand paper.