Yet more bearing questions?

[Super Sleeper]

I am looking at all the bearings on my x-block 355 (this was in my brother's 9.80 Super Gas car). He built this engine in about 1982 so I imagine some of the parts are going to be a little obsolete or at least hard to find. The main bearing set have P-series markings except for the #5, which is marked MICRO. It's a full width MB2559M. Was there a good reason to use a M-series #5 main bearing? I have the Mahle catalog and it doesn't list the M-series for a small block. It's 100% shiny.
Also, the rod bearings are not marked with a part # or letter code. They are 0.001 OS but just have a "T" and a date code, like 8 75. They are cut for dowel pins. Is there a way I can find our what series they were? Or just go with "P" or "H" series bearings all the way around?

20211104_120731 by Jim Harris, on Flickr
Here's a pic of the mains. Is that overlay fatigue, especially on #2? Is that a good reason to go the H-series bearings?
Thanks - Jim

 

[Ironracer]

Excellent questions, I wish I knew more about that. I was reading about the H and P versions last night.. couldn't come up with an answer on my own. There are Many good Mopar Mechanics here that will help you get some answers. And I wanna know too damnit!

 

[70aarcuda]

340 block?

 

[brian6pac]

Narrow bearing grooves.

 

[Super Sleeper]

340 block?

Yes, 340 X-block with 3.46 crank. More background on this thread Old Race 340 Teardown

Narrow bearing grooves.

Hmmm, hadn't noticed, good eye. I assumed they were uppers because of the oil holes. Maybe there was a design change since 1980?

 

[brian6pac]

Clevite Micro had wide grooves and you had to use 2 sets to get full groove because they didn't make a full groove set, So 2 sets of uppers was what we used.

 

[Ironracer]

Mopar Rod and Main Bearing Guide - Mopar Muscle Magazine

 

[Super Sleeper]

Hi - I am circling back to my engine as I gather parts to re-assemble it. I can't find the rod bearings, Clevite CN-481HDXN because they don't seem to be available with the dowel hole. Is that something that any machine shop can do or are there specialists? I am in the Seattle-Tacoma area if anyone has a guy they use around here?

Thanks - Jim