#1 Upper Main Bearing ---Anything Special ?

[pnora]

Pnora, ...I appreciate your dealership service dept experience & wished I had similar,.....Did you seem to miss or not notice the 1970 Plymouth Service Manual (group index 9--82) huge, Bold, black Warning Notation ? .... It's Much Bigger, blacker, Bolder Notation than even the Critical # 3 Main Thrust/Flanged Bearing (big deal important !! ). Non--interchangeable issue so I interpreted That # 1 Main Upper of Some Chrysler significance affecting issue to attend to......I remember back in '72 (my 1st Mopar engine teardown) asking myself "how does this well engineered, impressive Double Roller timing chain assembly get Adequately Directly lubricated",. but youthfully & ignorantly (no service manual),. assumed "it somehow just does" & tended to more Impressive sights as the huge ports, valves & piston valve relief Hemi things.....I was Super youthfuly Excited wrenching on my 1st New 426 Hemi !!!

Yes I remember seeing that. That was a long time ago. Maybe I missed something or forgot. At almost 69 I do get some CRS. I believe the chamfer was minimal and they most likely tossed the idea. There is a lot of oil getting squeezed out in the front. Front Main and Cam bearings. Then look at the big intake valley diagonal slot. That slot allows oil from the valley to pass through along with the oil pump drive gear slinging oil. Mopar was stupid with the manuals. They failed to edit them many times over and carried the same text from year to year. It was a joke in the tech schools. Look at these two photos

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[steve340]

I am not sure on your main bearing/timing chain issue. Probably worth investigating but you should be OK the bearing manufacturers are very good.
A lot of earlier engines used the link type (Morse Silent chain) and these did need a lot of oil.
The roller chain does not need as much oil.
Early connecting rods in some engines had a small squirt hole in them to send oil up on to the bore.
This required a hole in the rod bearing upper shell.
I think it was a 50's early 60's thing and got phased out when they went to lighter aluminium pistons.

 

[70rcode]

Ouch !! .....Kinda dry & crude photos, Pnora !! Isn't that a coincidence,....Over in "For A Bodies Only",....Just this AM,....."6PakBee" is looking specifically for genuine Mopar PN 2448379 (no aftermarket). Main Bearing..... That's the one ! 2448379. is the # 1 Main bearing..... He seems pretty locked in to wanting the real deal NOS. # 1 Main bearing...

 

[pnora]

Ouch !! .....Kinda dry & crude photos, Pnora !! Isn't that a coincidence,....Over in "For A Bodies Only",....Just this AM,....."6PakBee" is looking specifically for genuine Mopar PN 2448379 (no aftermarket). Main Bearing..... That's the one ! 2448379. is the # 1 Main bearing..... He seems pretty locked in to wanting the real deal NOS. # 1 Main bearing...

Good luck to him finding one. And why??????

 

[69Bee]

If you want to have an un-needed chamfer for oiling, lightly chamfer the tang side of the upper #1 bearing from the groove to the outside as the OEM factory parts had. Or you can just install them as is like everyone else does and forget about it. In all of my years of building Mopars, I don't recall ever seeing it.

 

[70rcode]

Thx 69Bee !! Apparently,... that's what I Did back in '72 when I was inside the motor,. Just Used a Std "Micro" Babbitt upper bearing.....I thought I had really screwed up back then (I've still never Noticed one) & thought All you guys were Using the Service Manual part.!!

 

[70rcode]

Not hung up on it .....Was more Curious about exactly How the bearing was Oem Configured to satisfy the Service Manual's lubrication concern....

 

[mopar 3 B]

If too concerned the lifter oil gallery plug could be drilled. It was the in thing at one time.

 

[mopar 3 B]

Where do you see dry timing chain failures to? I have been in a dealership service department since 1972 and have never seen any mopar with dry timing chain failures. So since 1972 I have never heard of any changes that affect timing chain oiling. There always have been changes like the slinger removal and maybe a few other items that we might of questioned. Never a main bearing change related to chain oiling that I am aware of. Your beating a dead horse here in my opinion.

I remember something about the slinger removal. Was this something that occurred on 72 and up cast cranks? I have only had one apart in that time range and don't remember if it was there or not.

 

[70rcode]

I've sorta been real conservative on Serious Mopar engine mods (like blocking Off or putting Holes in oil galley passages) & Not having any Noticable abnormal bearing Wear issues at my (1968--70 S/S equivalent) racing performance level, I just never Needed to go beyond the Full rear sump tunnel oil pan + dual line swinging pickup bolt--ons...

 

[66Satellite47]

In 20+ years of bracket racing with Clevite Hemi main bearings in my BB motors, never noticed a special #1 main. I never had any timing chain lube issues at 7000+ RPM either.