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Engine main bearing housing repair

About 1978 I had a 1963 Triumph TR4 with a 2200cc 4 cylinder motor and the center main bearing had spun. Being young and poor a low cost solution had to be found to get it running again. Making a boring bar that was turned by hand to machine the bearing bore oversize so a thick shim could be installed worked. Two dowl pins on each side held the shims in place. All including myself did not think it would last but as I was only making $2.60 an hour, I could not afford a better repair and had no choice as it was my daily transportation other than my motorcycle. Well it worked and when I sold the car years later as it was turning in to rust, the main bearing repair was still working fine and the car was run hard as I was a stupid 18 year old. I would measure the bore with the bearing cap on and torqued. If it is round and the correct size, I would run it.

Edit: I forgot to mention another main bearing story. My brother many years ago bought a 1970's BMW 530i car with a very noisy motor for basically free. The motor had been rebuilt but did not run well and had been driven thousands of miles like this while making a racket. The crank had been ground .01" under and they had installed standard size mail bearing shells so lots of clearance. Upon disassembly there was no damage to anything and the proper size main bearings fixed everything.
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I do like the stories of things that were half-assed and ran forever. But half-assing stuff is not the preferred method...and thus far, the OP has not said he wishes to half-ass the job.

Triumphs.... I had a 74 Spitfire with a scalded shaft in the trans. I took it to work, when I was 18, and did a 'government job' fixing it. I ground the bad journal down from about 1/2" to about 1/4" (!) and made a sleeve that I heat treated in the oil bath...pressed it on, ground it true in the end mill grinder, and put the trans back together. It ran for at least 5 year until I sold it....
I often replaced main caps in diesels using the best fit from the spares heap......provided the bore is OK top to bottom ,the swap will work.........seen quite a few truck motors with main caps broken ,and still running.
I worked on a 350ci Chevy, the complaint, low oil pressure. Dropped the pan, the 3 center main caps were laying in the pan!! The owner said it had been running with low pressure for 10,000 miles. Idle about 3-4 psi highway about 10 psi.
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With no oil passage to the bearing I think it will fail, unless you can get enough oil to that bearing through the crankshaft. (Which isn't going to happen above a certain rpm since centripetal force wants to push it out the other direction.)

I find it concerning that they appear to have gotten the width of that shell correct but it's cocked sideways, proud on top left and bottom right.
No oil hole on the second and fourth housings. Oil fed through the crankshaft. Alfa Romeo design.
The photo does not show it but the insert sits correctly on the housing. Camera optics/distortion.
Bobby Addison never fixed anything,if he could possibly avoid it..........anyhoo ,he got a Leyland truck he uses in his sawmill business,and always saying its got poor oil pressure...........finally his son pulls the sump,and one of the main caps is missing...not in the sump....just missing............not all bad,he buys another Leyland truck off me just to get the cap and bearing shells................It would have made sense to swap the motors,and use the motor that was OK......nope ,just swap caps ,thats the easy way.
Aluminum blocks do get welded for repairs one trick i use is a needle scaler after welding you peen the crap out of the weld it work hardens it back to a useable hardness. You can tell when machining it it will machine like the parent material. Learned this from a prominent top fuel crew chief.