Rod bearing wear with 440 Source crank & rods

Please note that I don't do this for a living... I never saw wear only near the tang before.

10.5:1 CR RB with 4.15 stroke in a 73 barracuda I purchased last year, I don't think the previous owner drove it very often, but when he did I suspect it got beat on pretty hard.

I took it apart because I found the #3 cam bearing spun during a cam swap and the more I look the worse it gets.

The crankshaft has no visible wear.

Main bearings are also in very poor condition, but do not have this concentrated wear by the tang, they just look bad everywhere.

I would suspect a bearing problem before I suspected anything else. And as a comment, based on the overall bearing condition it looks like that engine was assembled in a sandbox.

Me, either, which is why I'm going to follow this thread hoping for those that do to pipe in w/ some feedback.

I am gonna toss out an idea which may or may not have any validity: rod big ends not machined properly, which is causing the bearings to be "pinched" at the mating surface when torqued down. There may be some crank journal fillet interference, too.

looking at the dowel holes in the bearings makes wonder if these are correct. are those 527hd bearings? should the crank need 527n bearings. get a dial bore gauge and measure the rod big ends. double check the lubrication system and look for weak links.

I have torn down several small block stroker engines that had normal width bearings installed instead of the N that should have been used. Damage was more severe around the outer edges of the bearings and around the full circumference. One of them actually spun a bearing. Based on the pic I would start by checking the big end bore of the rods and micing the edges of rod throws on the crank.

They are CB527HDN "narrow" bearings, the 440 source crank has a pretty large radius on the rod journals, "maybe" a standard bearing would work, but I a don't have much experience with RB mopar engines.

The journals look very good, but I am probably going to try to get the local machine shop polish it and put it back together with King narrow rod bearings.

Check the bearing crush.
This link may help:
Mahle bearing failure

A couple of pics from my own engine which hadn´t even been started, just turned over for assembly.
Bearing crush was 0.008-0.010" instead of recommended 0.006". All eight rod bearings looked the same.

Wow....Never had a set come out looking like that...And we have run a lot of their kits. Myself personally, I have had 4 engines with all 440Source parts and never saw anything like that.

I would say it almost looks like the tang fit too tight into the tang relief of the rod. Like the relief was too small and didn't allow the tang to fully seat before applying the full torque to the bolts.

The other wear at the edge of the bearings looks like bad some bad machining.

so I am a lets look at the whole picture kind of guy. So spun cam bearing to me means another block, If I had to have a block machined I am taking the crankshaft with it to either have it polished or turned to .010. The machine shop should be able to tell you if the journals were poorly ground. If that all looks good then have the rods resized. Should be ready to rock after that. Birdtracker

I've seen cam bearings spin in stock blocks and had no issues reinstalling another set of new stock cam bearings and having the motor live a long and happy life after getting problem fixed that made that cam bearing spin, not enough clearance to the cam journals
All the replacement cam bearings I've seen and used are mainly all Babbit, which is very soft so as long as you remove the excess Babbit stuck to the block so the new bearing installs correctly, round and enough clearances to the cam journals
IHTHS

What does the backside of the bearing look like? I'd be looking very close at the rod big end for burrs/out of round/deformed tang groove.
Doug

It looks like somebody just bolted it together in their garage without having the rods resized and they probably hammered the cam in and clearly there was a pile of foreign debris involved. Sounds like you typical cul-de-sac special to me. Hey, at least the rotating assy came balanced lol!

I installed new durabond bearings and the old cam would not even think about going in all the way... so I used a pretty barbaric method to "fix" the problem.

This. I have found burrs on either the tang of the bearing or the tang groove in the block. It will hold the bearing from seating in the bearing saddle properly. Quality control sux nowadays. The burrs in the tang grooves are more likely if the block is line bored or honed. Also if you check the bearing journals on import cranks they will vary end to end. I have seen as much as 3tenths.

In my experience the problem is the journal being tight and it's usually on the middle or 2nd to the rear cam journal. The correct way to fix this is honing out the cam journal prior to installing the bearing. Aka dial bore gage the cam bearing tunnel prior to assy just like any other bore on the engine. Scotch bright scares me around a half assembles engine!

It is completely apart now... I will try to clean it up pretty well before reassembly.

I was like... DANG thats one crazy old school dwell cam. Then I got it.

That wear looks like the rods where not machine correctly at the bearing tang sides, the rod bearing tangs bearing side is sticking out (not completely round) far enough to make them wear
I had one Oliver Hemi rod like that, the bearing tang slot was too narrow to allow the rod bearing to seat properly
They, Oliver, paid to have it ship back to them over night by Fed Ex Express and fixed it the next day and shipped it back to me that night by Fed Ex Express Twod ay turn around

I've seen this on a build where they had a Source crank. It turned out the fillet radius on the journal was too big & the bearing showed it. To fix our situation, we chamfered the edge of the bearing.

i've never used a Source crank before but have heard of them having large fillets. unfortunately, this is a case of not checking things. this wouldn't be difficult to check with a couple of new bearings and a magic marker. rod side clearance should be checked too. measuring big ends of the existing rods and comparing that to a stock rod, doing the math, should get you close to where the clearance should be, IF the filet/bearing clearance is correct. i'd still go thru the oiling system to make sure there's adequate supply. keep in mind the rod bearing is one of the last parts to get oil. adding some chamfer to the bearings wouldn't give me heartburn considering the alternative.

I have recently had some bearing tangs that needed filed before they were seated .