Micro Welding of bearing shell to rod housing bore
 

Any ideas ?
Could it be when the combustion occurs the bearings take a hit in the middle causing the outer parts of the shell to move away from the housing just slightly and then return causing a fretting action and transfer of metal, from shell to housing bore.

Re: Micro Welding of bearing shell to rod housing bore
 

Rods out of round or inadequate bearing crush. I'm just spit balling ideas.

Re: Micro Welding of bearing shell to rod housing bore
 

Bearing type/part number and rod type and application?
General answer: Fit in housing bore
Pictures?

Re: Micro Welding of bearing shell to rod housing bore
 

Manley rods, King not as bad as Clevite 77, housing bore round according to AG 300. No pictures all the evidence is gone, removed.

How is bearing crush measured and where can the specifications be found?

Oil is semi synthetic

Re: Micro Welding of bearing shell to rod housing bore
 

I don't know if it's correct or not, but I use a height gauge to measure each shell and to verify that the shells are square, which I've found some that are way off. I've had rods on the small end of spec as well as the big side both do it. :confused:

Re: Micro Welding of bearing shell to rod housing bore
 

using too thin of an oil ?---oil is not "thick" enough and not enough "pressure on the bearing" to keep the proper spacing between bearing and crank

Re: Micro Welding of bearing shell to rod housing bore
 

Larry,
Are you saying the Micro Welding is happening near the ends of the bearing?


Stan

Re: Micro Welding of bearing shell to rod housing bore
 

How much clearance are you running and what oil weight?

Race bearings usually have additional crush built in them. Are you using a torque wrench or a bolt stretch gauge values? Make sure the main bore is round and check the size without and with the bearing installed.

This is a method used to check crush.
https://lh3.googleusercontent.com/pr...cfIEn5dIZLriTg

Re: Micro Welding of bearing shell to rod housing bore
 

I have seen the microwelding almost 3/4 the length of the bearing, and probably 3/4 of the width on the most severe ones.

Re: Micro Welding of bearing shell to rod housing bore
 

2.375 crank pin, 5W30 oil, close to .003 vertical bearing clearance, bore is round within .0002, stretch gage.

I'm not understanding how to check housing bore diameter with the bearing installed.

Thanks

Re: Micro Welding of bearing shell to rod housing bore
 

The welding on my 440 stocker engine is on the piston side of the rod. If the rod parting line would be 3 o’clock and 9 o’clock with 6 o’clock on the piston side. The most of the transfer of metal is between 3:30 and 4:30 on one side and between 8:30 and 7:30 on the other side, with very little if any at the 6:00 o’clock position. Rod and piston approx 1750 grams.

Re: Micro Welding of bearing shell to rod housing bore
 

The bearing has a thickness specification that can help you determine the amount of crush you are getting after you torque the rod. How many use cycles do you have on the bolts and what type of bolt are you using?

Re: Micro Welding of bearing shell to rod housing bore
 

OK, I have no personal experience with this problem. But have talked with someone who I believe had a similar problem. He modified his rod bearings to give a little more clearance in just that area and that seemed to fix his problem.

Stan

Re: Micro Welding of bearing shell to rod housing bore
 

I have never had this problem. A long shot. Do you have your negative cable attached directly to the block? Ray

Re: Micro Welding of bearing shell to rod housing bore
 

Yes Ray the cable is connected to the block. I never considered an arcing or plating situation
Not sure on cycles on rods or bolts. Bolts are ARP 7/16 20NF 12 point. The big end of the rod stays rounder longer since we installed a clean neutral valve body in the trans. I use the brakes to stop the car without compression braking.

Re: Micro Welding of bearing shell to rod housing bore
 

Larry,
The design of the bearing is important. The size of the rod bore determines crush. You may need a bearing with more ellipse or a slightly thicker oil for the .003 clearance.
It is a long read, but Mahle has a good read on bearings.
All bearings are not created equal!
https://www.speedperf6rmanc3.com/con...20Bearings.pdf

Re: Micro Welding of bearing shell to rod housing bore
 

Thanks. I will read it

Re: Micro Welding of bearing shell to rod housing bore
 

Which Manley rod and which arp bolt ?

Re: Micro Welding of bearing shell to rod housing bore
 

Glenn I cant find the info on bolts or rods. Bolt stretch is .0055.

I need to finish my engine to race BG this weekend so my response time will be long until we are at BG.

Thanks everyone for the help and input.

Re: Micro Welding of bearing shell to rod housing bore
 

Strange.

So there is no indication of an oiling problem? i.e. crank to bearing face contact/damage?
Or bearing shell being hammered (detonation)?

Any indication of the caps moving on the rod (fretting on the cap/rod contact surface?

Fretting/welding indicates parts are moving under load. Initial thought would be to tighten (decrease) the bore size to the minimum to increase the crush.

All I got. Will be watching for responses.

Re: Micro Welding of bearing shell to rod housing bore
 

The caps have dowels and the mating surface looks perfect. The upper shell is always not as tight as the cap shell in its bore.

Is there a certain finish that the bore needs to “hold” the bearings?

Re: Micro Welding of bearing shell to rod housing bore
 

I've been reading this thread and wondered why no one mentioned detonation as being a possible issue.

It can show up in rod bearings....

Usually the shells just fall out....and might have some odd looking wear marks....

Re: Micro Welding of bearing shell to rod housing bore
 

If the problem didn't exist, and now it does, something happened. I've seen upper bearing shells beat up to the point they just fall out of the rod.

Fly poop on spark plugs? Fuel change? Verify timing and TDC marks? Try another known good timing light?

Just reaching here.

Re: Micro Welding of bearing shell to rod housing bore
 

or cam change too!

Re: Micro Welding of bearing shell to rod housing bore
 

First noticed it when we started getting close to the 590 hp number. Damper is on TDC, fuel seems to make no difference c11, c12, c10, renegade 116. cam changed made no difference.

Re: Micro Welding of bearing shell to rod housing bore
 

If the engine is apart and obviously it is....

Look at the ring lands and the tops of the pistons for any oddball signs that usually indicate detonation. Pecker tracks on pistons, or on the sides of the pistons above the rings. Ring lands beat up....

If all is clean then you can rule it out....

It's not likely but I thought I'd throw it out there.

Re: Micro Welding of bearing shell to rod housing bore
 

Just thinking out of the box, how old is the Harmonic Balancer?

Re: Micro Welding of bearing shell to rod housing bore
 

At least 6 to 8 years old. Last time it was down I had crank checked for balance it was ok

Re: Micro Welding of bearing shell to rod housing bore
 

What brand of balancer are you using?

Re: Micro Welding of bearing shell to rod housing bore
 

A good read on honing the big end of steel rods is in the SA Design Jenkins small block Chevy book I’d how he puts .002 shim stock the hens the rods round then removes it. The rod is now out of round but high rpm it stretch’s back round as I remember it’s when the rod does not have enough material at the parting line.

Re: Micro Welding of bearing shell to rod housing bore
 

That sound like a better way than modifying the bearings.


Stan

Re: Micro Welding of bearing shell to rod housing bore
 

ATI balancer

Re: Micro Welding of bearing shell to rod housing bore
 

You should have the harmonic balancer refreshed by ATI.
Although it balanced with the rotating assembly, it does not have anything to do with the operation. It has to more to do with harmonics dampening during the engine operation under load.

Re: Micro Welding of bearing shell to rod housing bore
 

This is when there weren't any good connecting rods available. Today's rods stay round even at higher rpm. That's if it's a good quality rod. Crower, Callies, etc

Re: Micro Welding of bearing shell to rod housing bore
 

If read the article he was talking about Carillo (not sure of spelling) rods they are shown in the book. At that time there were good Steel aftermarket rods available.

Re: Micro Welding of bearing shell to rod housing bore
 

I got to speak with Glenn Briglio in person yesterday, what a wealth of knowledge, and he advised changing out the ARP rod bolts to a higher quality bolt next time. And then the sprinkles fell.

Re: Micro Welding of bearing shell to rod housing bore
 

Dan Beagle from Mahle spoke on the subject and said low radial pressure on the bearing shell could be a possible answer. This was on the AERA webinar.

Re: Micro Welding of bearing shell to rod housing bore
 

Mr Beagle advised to check with the rod manufacturer on correct ID finish in housing bore. It maybe to smooth and allowing the shells to move.

Re: Micro Welding of bearing shell to rod housing bore
 

Maybe you need a oil with more EPI activities To keep the oil from being squeezed out!