I have a question about main bearing material. has anyone ever made a new bearing from 660 brass or 932 bronze or even delrin? I know the aluminum bearings are original but having modern materials and machine shop in my back yard is peaking my curiosity. I'm more interested in durability than originality that can't be seen. Cat pricing is around 300 bucks for the two main bearings and I'm not scared of paying for quality but 70 years of progress makes me wonder.

Years ago I had a7U and the pony pulley had so much slop the seal was leaking a lot of oil . Pulled it apart and found the journals were undersize. No replacement bearings were available.
My dad, being an old machinist, had some old brass bars in his toolbox. A couple of hours on the lathe and he had the crank turned down and new bearings made to match. I ran that machine
many years and never had any trouble. Don't know the spec on the brass but it worked. Was 35-40 years ago.

The bearings we get from Cat are probably over designed for our use but they were once made for machines that were used day in and day out so had to have good pony bearings. The "Aluminum" bearings one gets from Cat probably have alloys of Silicon and Copper in them adding considerably to the cost. The silicon and Cu give it toughness and the silicon helps polishing the journals. Whereas a lot of different materials would work one would have to be pretty lucky to guess what would work as well as the originals.

On a different subject, while I was typing away all at once I got about 40 pages of program lines and had to start over. See photo.

no reason you couldn't use brass or sintered bronze.

i did see a post on here where someone had made bronze bushings and modded the crank and bearing housings so he could make and fit some thrust washers to stop the crank end float problem these engines are known for. end float as factory is controlled by the bushes and a dowel pin. dowel failure allows the bush to rotate and move out of place damaging the housings too.

a old farmer gave me a tip once to help save the crank bushes make a couple of timber wedges to support the flywheel when it not running as the weight of it and vibration of the machine when running will walk the crank through the bushes.

How many reciprocating engines or compressors have you seen with brass or sintered bronze bearings?
Me neither.

Just curious but ordered new cat bearings

they are reffered to as bearing by cat but they are actually bushes. a bearing has multiple pieces usually rolling elements contained between a inner and outer.

it was very common to use brass or bronze bushes on shafts and cranks before roller and ball bearings were developed. piston pumps commonly just had bushings. many old stationary engines just had bushes too usually brass or bronze. lubed with oil or grease.
white metal(babbit) was also common and is still used today except its not cast in place and scraped any more.
if you think bronze is too soft there are aluminium bronzes that are that hard they cant be machined and have to be forged.

sintered bronze is self lubricating as it is sintered with carbon and is even better if it has oil applied to it

None of those put put motors turned at any significant rpm and I don't know anything current that runs on brass/bronze.

According to my IC Engines book, a bushing is a bearing but not all bearings are bushings. A bushing is one type of bearing. Another example is that an air bearing looks like a bushing but it is a no contact type bearing that operates with a layer of air or gas separating the rotating components. Although it looks like a bushing it is always referred to as an air bearing. Air bearings were used on the arming motors on the Poseidon missile warhead, at least that was what we referred to them as.
My cousin worked for Furniture Row Racing and Truex team building engines for them in Denver. I asked him this afternoon if he was aware of any engines with brass or bronze bearings and he just laughed.