I recently rebuilt my 455 olds and after about 1 hr road time I lost oil pressure so I cut the oil filter and it was full of copper. I tore it down and # 3 & #4 main bearings were gone. My machine shop said I was detonating the engine and thats what took out the mains. My question is would there not be signs of detonation on the spark plugs, (little metal flacks or something to tell?

 

Was there any vibrations as you drove it? Because it sounds like a severe case of out of balance along with the crankshaft alignment also. I never heard of that bad of detonation and I have had some in my time and it never wiped out my mains. How were the rods?

 

With detonation that bad you might not even have the electrodes left and yes you should have had some metallic flaking on the insulators. Also was you oil pump working and was it new? What brand? Sorry to hear about such a disaster after you put all that time and money into your new motor. One way to check your Crank is to install it with the bearings and torque the #1 and #5 mains to 120lbs and with a dial indicator check the runnout on #3 and check #2 and #4 if you get 0 runout your good you can have up to .001. I have seen crankshafts fit in the block and the clearances were ok and then chew up the bearings because the crankshaft was out like crazy.

 

So sorry to hear about your motor. My god, if you had detonation that severe for an hour, you'd of known it. Is the machine shop going to help you out?

 

Sounds sketchy to me
oil pump pickup loose or too close to the pan?

Who assembled this engine?

I have taken several engines apart where the ROD bearings were getting eaten- typically they hug the journal and not the rod, like the C shape is collapsed a bit- I figured that was from taking a pounding from detonation.

To eat the main bearings first sounds like oil starvation. Or, the crank passages did not get cleaned before the crank was installed. Seen that done once.

 

Do you have pix of the rod bearings?
Sounds like a bent crank and/or junk in the oil passages.
Pix would be a big help.

 

Detonation sure gets blamed for a lot of bearing problems when it comes to 455 Olds Ive noticed, can you put up some pictures, how did the rod bearings look? You will find it wasnt detonation. Assembled dirty, improper clearences, runout in the crank, oil pickup not clearenced to the pan correct, these are a few things it could be. I think cuttlassefi's advice should be listened too, he's an expert in these types of situations.

 

It did vibrate some but not excessively,The crank was supposedly checked for alignment when it was ground.The rods were good, I could put them back in again, but I won't.

 

The pump is a Melling m22hv and it was checked and showed little wear so it was reused.I will carefully recheck everything, I thought I was being carefull last time!!

 

That's why this is such a mystery,I assembled the engine along with a friend who did it for a living for 40 years, He made sure everything was cleaned and ALL the oil holes and galleries were boar brushed. We double checked every clearance three times.

 

I could show pics if I could figure out how to post them!!!

 

post them on photobucket, every picture you put up on photobucket comes with a direct link its like [IMG] blah blah [IMG/] something like that. you can use those links right in these text box's to post pictures, thats what I do, works really well because I can send pics from my dumbphone to my photobucket

Also Im willing to bet money something was just wrong with 3 and 4 main bearing, Ive noticed number 5 Doesnt take a beating because the extremely large tolerances on number 5 bearing. that being the case, if something was wrong with the whole oiling system, your cam bearings would be thrashed along with 1 and 2. thats just my .02 cents though. ive seen strange things happen.

I had a friend put the wrong distributor in an engine, probably chebby, but could have been ford, cant remember now, and it ran fine, but didnt oil 1 side of the lifter galley. couldnt figure out why one side always clacked, until we tore it down and saw lots of metal

 

Thanks, I will try to use photobucket!!!First I need to take some pics.

 

That stinks, good luck man. Hope the machine shop stands by their work. Most dont, atleast around here.

Just had a trans grenade in my dads GS after one run at the track, guy who built it told my pops he can fix it now for $500. Meh! Dont think so!

Good luck. Post those pics. Theres a bunch of smart people on this site willing to help.

 

Solid motor mounts have been known to cause # 3 & #4 main bearings to grab ahold of the crank when the block flex's but I know you weren't getting on it hard with only an 1/2 hour on the engine.

I would think probable causes to be things like, the crank wasn't straight, the main bearing clearances were too tight or as mentioned above, a lack of oil to said main bearings.

 

No, I don't use solid mounts,and my clearances were @ .003 1thru 4
and .004 on #5. Like I said before this makes no sense and were open to any suggestions. Thank you for yours.

 

Your cleaning and assembly process sounds proper.

is the crank out?
can you [did you] ring test it?
A cracked crank will produce a dull sound
A solid crank will ring nicely

a forged crank, supported on foam blocks while packing for shipping, will "tinggggg" for a very lone time - like minutes - when struck.

If it's not oil feed or crank flexing, I am stumped.

photos please

 

Very unlikely to be detonation. You would see it on the piston tops. Bent crank is the next logical check. Some say crank flexing. However I would think you would be hitting the go pedal softly with only an hour on the motor. But if you did hit it hard, possible. If you did the assembly yourself hard to go back to the machine shop for recourse, unless you found something very obvious. Only way to find out is start a tear down and check every part.

 

I will test it that way thanks for the ideas!!!

 

You are correct and we will be inspecting every piece for evidence