Small block 360 bearings look bad....................

We pulled a 360 down and the bearings look bad. Bearings 2, 4, and 5 don't even fit snugly into the main bearing cap anymore. They seem like they are egged. The lead overlay on number 5 bearing pretty much flaked out.

These bearings have about 30 passes on them.

What do you think the cause of this is? (see pics)...

What do the rods look like?

Haven't got that far yet.

I think 30 passes caused that damage.

Does your motor have the lifter galley oil modification that puts mote oil to the bearings?

Nope, the block isn't modified.

1) How high did it get twisted???

2) How much temp did it see???

3) Oil???

Not enough clearance. Crank grinders like to grind your crank on high side, bearing manufacturer likes to give you bearing close to max wall thickness and old blocks main bores shrink from heat cycling. Now that it has bearings that look like these, guaranteed main bores have shrunk. Probably needs line honed.

When you get crank turned have turned .011-.021-.031 US to give you more bearing clearance. Clevite now makes bearing in std with ex clearance so if you have a new or good std. crank use part # MS1266HGX

An engine with a little to much clearance will run forever, one a little to tight will die young.

6,000 RPM.
Runs 180-190 degrees.
Oils looks good.

About the same as we were thinking....thanks

Are you running a four speed still? four speeds are hard on parts.

Sorry to hear of your loss.

This is (was) in our '65 Dart. With a 727. Not a huge loss but just curious what happened.

What oil pump?

What oil pan?

360 large mains need more oil to keep up the larger journals. High volume pumps will pump the pan dry.
Just an idea.

Factory pan, standard volume pump.

I don't buy not enough clearance with damage that bad in only 30 passes on a mild build. I'd like to see all the bearings, rods and mains. What is "oil looks good"? It must have metal flakes in it, correct? What were the bearing clearances set at when it was built? Was it pre-lubed? What pressure was it running at? Why did you disassemble it in the first place? Internal noise? What does the oil pick-up screen look like? Are ALL the internal galley plugs correctly installed? A lot more investigation needs to be done before a proper diagnosis is made. Plenty of stock lower end 360's running around that stay together under quite a bit of abuse. Lets find the actual cause so there won't be a repeat.
Doug

Didnt happen to mix and match main caps from a different block????

mains were .002 clearance, oil pressure 30psi hot at idle. Prelubed. we'll take it down further in the next few days.

Hows the cam bearing look, or still in the motor?

Good enough.
Doug

.002"? Measured or plastigaged?
That should be plenty of clearance provided the crank was ground without taper and the main bearing bores were correct when you assembled. You might want to think about replacing the main bolts too. That cap's parting line looks a little strange to me.

What does the crank look like? It is rough or discolored? That really looks to me like it was run out of oil.

i'd be curious as to what the thrust bearing surfaces look like. could the converter be balloning and seriously screwing up the end play? something definitely chewed the engine outside/tranny side of the bearing.

Crank is perfect, it wasn't run out of oil.

Think we figured it out with more investigating...the bearing caps weren't sitting correctly. High spots in the bearing saddles.

Thanks guys. It will all be torn down and re-machined anyway.

Well look at it this way. At least you caught it before things turned ugly and thank God it's Winter. Lots of time to fix it right

When bearings are egged shaped, it usually means detonation. Unless you are running really thin oil, .002 MEASURED clearance is too little for that big main bearing. I would use nothing less than .0025 and would go to .003 if you are using anything heavier than a 40 grade oil.

A high volume oil pump WILL NOT, NOR CAN IT, pump the pan dry any faster than a standard volume pump. Sort of like the long tube/short tube header thing...who determines what is long and wht is short? If you up the engine speed past OEM (which is generally a sustained speed [RPM] of over 4500 because the factory considered most people never twist them up for long periods of time) then you should have the "high" volume oil pump.

If you want to talk to some one who can explain this to you, call Kevin Johnson. Just google crank scrapers and you will find Ishihara-Johnson crank scrapers. Call him up. Take notes.He is a smart man who doesn't bull crap you around.

You have more issues than you think IMO.

Can you explain this a bit more...Id like to learn more and im sure others would as well.

"Think we figured it out with more investigating...the bearing caps weren't sitting correctly. High spots in the bearing saddles."

Was this a junkyard block? How did you set the clearances?

Upon assembly with the caps set on the register other then maybe a tap with a very small screwdriver sized rubber mallet they either fit correctly or they dont.

Id think you should of been able to pick up on something upon assembly.

Maybe I missed it, but I haven't seen or heard what the rods look like. I've dealt with enough oil issues in stock crank, high RPM 360s to find it hard to believe a main could get to that point without the rods coming out of it first.

6k is not a lot of RPM and it shouldn't take radical oil system mods to keep it happy. There are some basic things that would be helpful though. You can take it apart and fix it, but I'd want to know why that happened rather than just hope it doesn't happen again.

ETA...I'm with Porter67 in that I'm not sure what that statement means. But I'm curious.

The only thing I can think of is there was something on the bore of the main bearing. Don't know if its metal or what. I'd like to know what they found.

I guess it's possible there wasn't any press fit between the cap and register and it let the cap move on the bolts.

Just guessing though.

In my 40 years of building and tearing apart engines I've seen a lot of things that are put together poorly. I tore apart a small block 360 one time that was still running and raced (hydraulic cam and sounded like dog-poop till reved up) that had 3 oil galley plugs missing. I tore one apart with the bearing installed with the oil feed hole installed in the cap instead of the block. one had .010 bearing instead of the needed standard size. Engines put together straight from the machine shop without the proper cleaning. ZERO thrust bearing clearance and many others.

Depends on how far it gets taken...


I've 'dressed' more than one main cap before assembly...

That was about oem blocks and caps, now my race blocks the register is much tighter and I thump then with a short wooden block and as well need that same block to remove them.

But I have seen shops use a big chisel near the cap to move a bit of material before align hone job...mixed thoughts on that.

But most oem caps seem to just fit snug vs tight, but ive only done 40 or so small blocks over the years, im sure others like John for example have seen the full barrel of monkies.


Id just like to know more on this deal so I can try to avoid it in the future.

The crazy thing about the engine without the 3 pipe plugs is it was in my black Duster when I bought it and ran 11.80's with a 510 lift purple shaft hydraulic cam. Matt raced it the year I bought it till I built another engine for it. While idling in the pits or driving it around it sounded like CRAP. From the water box on when it was reved up the pressure must have been high enough to pump up the lifters. The 3 plugs missing and the one that really surprised me that it had enough pressure not to harm the bearings was the one on the rear driver side oil galley. The other two not so must as they mainly direct oil thru the oil filter. Those were the small vertical one located under the rear main cap and the one under the 90 degree oil filter adaptor.

The parting line looks like the cap isn't seating right. Possibly a weak bolt or cap flex which would be odd for such a heavy cap (#5). But something looks fishy there.

Does the block side bearing look the same? Just wondering if that cap/saddle isn't square.

lets see a picture of the thrust bearing please. both sides.

Wheres the pics of the other bearings and crank?
Doug