Spun 360 Rod Bearing

[TT5.9mag]

I’m with PRH I wouldn’t mind the clearance as measured on the mains. I’d run at least a 10w40 in it though. Check hot oil pressure and decide. You can get king bearings in .010 +1 last time I looked if it really bother you. I think it’s just an X after the part number. Call em and ask. When you say end play is .003 is that the thrust clearance? If so I’d open that up a bit. More for a stick car.

 

[SpeedThrills]

A couple of things I noticed. The rod journal shown on your crank has what looks like a step on each end where you would normally see a radius or fillet. Right where the cast finish meets the machined finish. Hard to tell from just one photo, but that looks fishy to me. You don't want sharp corners on a crank journal, it concentrates stress in that location. That's the main purpose of the fillet.

View attachment 1716423550

The other thing I noticed is your spun bearing has what appears to be a corresponding step on the side of it, where it looks like it may have contacted the step in the crank. Look on the left side of the bearing in the pic below.

View attachment 1716423551

So my question would be is the bearing hitting that step in the crank? That's what it looks like from the pics.

When you reassembled the engine did you check the side clearance on the rods with a feeler gauge? I don't know what year your 360 is, but I show .006 - .014 side clearance for a '71. You should be able to torque both rods on the journal and be able to physically move them fore and aft with your hand a bit.

A related question. Once you get your new parts and are ready to reassemble, take some layout blue (a black sharpie works in a pinch) and put it on the side of the rod and bearing. Assemble a rod on the journal in the orientation it will have when running. Shove the rod fore or aft against the crank cheek and rotate it a revolution or two by hand while holding pressure against the crank cheek. Take the rod back off the crank and look at the bluing/sharpie ink. What is hitting first when the rod stops moving fore or aft and it contacts the crank? You don't want it to be the side of the bearing.


Again, hard to tell from just a couple of pics, but that caught my eye.


Cheers.

Thanks for the thoughtful response. Desoto291hemi explained it in his reply. I had no clearance issues in that regard. The cut on the edge of the bearing occurred when it spun and metal came off the crank, allowing the bearing to dig in.

My .02……
.004-.0045 main clearance in this application wouldn’t bother me any.

This is what I need to hear.

On a Mopar,,,,all the cranks had an undercut filet from the factory .
They didn’t use a radius on the edge of the journals,,,still worked pretty good .

Tommy

Mine was okay until that bearing spun, anyway. lol

I’m with PRH I wouldn’t mind the clearance as measured on the mains. I’d run at least a 10w40 in it though. Check hot oil pressure and decide. You can get king bearings in .010 +1 last time I looked if it really bother you. I think it’s just an X after the part number. Call em and ask. When you say end play is .003 is that the thrust clearance? If so I’d open that up a bit. More for a stick car.

I'm thinking of 10W40 after I run it with 10W30 break-in oil. (I ran it with 10W30 last time, good pressure.) I'll think over +1 bearings. Peace of mind thing. I'm going to re-check the end play (yes, thrust). I know it needs to be pried a bit forcefully to get it to move all the way. Spec I found is .002-.007.

Someone else mentioned rod side clearance. Last time I put it together, it was between .012 and .013 on all of them. I haven't checked it this time yet. Pistons/rods aren't in yet.

Filing rings is next... (Well, after re-checking the thrust, and mulling over +1 mains.) Thanks all!

 

[Desoto291hemi]

I know everyone has their own opinion,,,,but I’ve always tried to keep the thrust clearance on the tighter side if using a stick shift .
Every time you push on the clutch it is applying force to the thrust bearing .
So,,,your 3 thousandths check on that sounded just fine .

Like the man said earlier on your bearings .
Yes,,,, there are undersized bearings available,,,,,usually 1s,,,,I have seen 2s .
And 11s,,,and so on ,,,they rare but can be around .
It just depends on what application you are running .
The more popular brands usually have more support in the aftermarket .

Sometimes you can get lucky and find odd sized bearings that people have hoarded up .
I have several sets of undersized bearings,,,,,but not any for the 360 .
Most of my stuff is big block,,,with a little bit of small block too .

Good luck ,,,I hope it works out for you .

Tommy

 

[cookietruck]

I’m with PRH I wouldn’t mind the clearance as measured on the mains. I’d run at least a 10w40 in it though. Check hot oil pressure and decide. You can get king bearings in .010 +1 last time I looked if it really bother you. I think it’s just an X after the part number. Call em and ask. When you say end play is .003 is that the thrust clearance? If so I’d open that up a bit. More for a stick car.

The King X bearings add .001” of clearance.
But I just looked and they have them for .001” and 011” on the mains which I assume are for std and .010” ground cranks that need to toghten up the clearance by .001”

 

[Kuz]

On a Mopar,,,,all the cranks had an undercut filet from the factory .
They didn’t use a radius on the edge of the journals,,,still worked pretty good .

Tommy

Thanks!

 

[RustyRatRod]

I would not proceed until I had that crankshaft DEAD NUTS right. That means whatever it takes to get it there. I'm not a fan of one size rod bearings on one throw and the rest another size, so if that throw needs turned, I'd do all the rod throws. But let the shop measure and then proceed with whatever their recommendation is to get the crank RIGHT. At this point, I'd have the big ends of all the rods checked, too.

 

[RustyRatRod]

......and for what it's worth, I'll break ranks. There's no way in hades I'd "settle" for .004" main clearance. Maybe on a crank with a 12" main journal. .004" is like a screen door on a submarine. Considering the spec is .0005 - .002, that means you're TWICE what the maximum spec is. No thanks. Not in my engine. But if that's what you want, carry on sir.

 

[SpeedThrills]

My two choices were:
A) Get the Kings bearings that are .001 tighter. (.011 total in my case)
B) Get Clevite 77's, because from reading on here, and around the web, they, for some reason, measure .001 tighter. (The .010 version that I need)

I chose A. I checked them out today. They did measure tighter. They're all right around .0035, using a dial bore gauge. Using Plastigauge, they're all around .0025, about .001 tighter, as compared to the Kings, which also were about .001 tighter with Plastigauge.

End play is .004".

Runout on #3 is .000. Runout on #1 with #3 and #5 supported is .001. Runout on #5, with #1 and #3 supported is .001.

While I was waiting for the bearings, I gapped the rings. Now I can finish assembling the short block. That's all been checked before. I do have to check rod side clearance.

 

[furrystump]

I’m running VR1 and have for 3-4 years. Solid flat tappet. The weight is stupid, but it has worked for 15 years and sometimes I’m just silly like that. 20w50 sure I’m giving up some HP. 25-30 lbs at idle hot.

 

[SpeedThrills]

I’m running VR1 and have for 3-4 years. Solid flat tappet. The weight is stupid, but it has worked for 15 years and sometimes I’m just silly like that. 20w50 sure I’m giving up some HP. 25-30 lbs at idle hot.

I have Royal Purple 10W40 break in oil. The cam and lifters have been run before, they “should” be okay. I just need to break in the rings. I plan on driving it right after starting it, to load-unload rings.
I like the idea of VR1 after break in. Just have to decide what weight. Rods are just a bit tighter than the mains. I’m leaning 10W30. It’ll be a while. The heads are “heading” in for guides and a valve job the 14th.
The big slow down will be that I’m going to paint the engine compartment, and I think that will lead to painting the entire car. Get it over with.

 

[MOPAROFFICIAL]

Yeah I would do like everybody else's mentioned already, have the crank polished on that journal and have that one rod resized. Put it back together with some good bearings and enjoy it. You can run a lot of clearance, and it's a good thing when you're turning RPMs... maybe not as great when you're at idle and the pressures really low but it doesn't mean anything is wrong.

 

[SpeedThrills]

Yeah I would do like everybody else's mentioned already, have the crank polished on that journal and have that one rod resized. Put it back together with some good bearings and enjoy it. You can run a lot of clearance, and it's a good thing when you're turning RPMs... maybe not as great when you're at idle and the pressures really low but it doesn't mean anything is wrong.

This thread has gotten kinda long. I just want to mention that in post 19, I listed what was done to the crank.
Bottom line: the mains were polished, and all the rods were taken to .030 to clean up the #8 that spun. Crank, rods, and pistons are back in.

 

[MOPAROFFICIAL]

This thread has gotten kinda long. I just want to mention that in post 19, I listed what was done to the crank.
Bottom line: the mains were polished, and all the rods were taken to .030 to clean up the #8 that spun. Crank, rods, and pistons are back in.

Damn. Carry on then. Lol

 

[SpeedThrills]

Damn. Carry on then. Lol

Not at all. I appreciate your input.

 

[furrystump]

With the correct finish on the cylinders, new rings are basically seated just turning the motor over as you put it together. Low tension rings are different animal. Most ring seating failures are bad surface finish or out of round or tapered bores or fuel washed bores on start up.