how to identify 4.0L bearing size?

I'm thinkin about replacing my main/rod bearings while I have this motor out (87 4.0L w/ 130K miles) and I already have to pull the crank to get the rear main out (it's fighting with me)

I looked at the rear main bearing and there's a marking on there that says 010, does this mean it's .010 oversize? (I can post a pic tomorrow if needed)

isn't there also a marking on the block?

There's a small boss on the passenger side of the block, nect to the distributor shank. If the main bearings are 0.010 undersize, there will be a letter code stamped in that boss.

They used 4 letters. Going from memory, M was for undersize mains, P was for 0.010 oversize pistons, C was for 0.010 oversize cam bearings, and the one I can't remember was for rod journals. No codes is supposed to mean everything is "standard."

would there be any kind of marking on the crank?

I found a large "BH" around the area that you mentioned.

I gotta take the crank to my machinist. there's one small score that I can pick up with my fingernail on the surface for the #3 rod bearing. 3 & 4 rods are showing quite a bit of copper through, the mains look perfect aside from some strange spots on the bearings (can't feel them, but the look kinda like waterspots on paint)

Eagle said:

There's a small boss on the passenger side of the block, nect to the distributor shank. If the main bearings are 0.010 undersize, there will be a letter code stamped in that boss.

They used 4 letters. Going from memory, M was for undersize mains, P was for 0.010 oversize pistons, C was for 0.010 oversize cam bearings, and the one I can't remember was for rod journals. No codes is supposed to mean everything is "standard."

Click to expand...

I came across this in the simular posts area at bottom of thread, this may have been what I saw the first time. If anyone can expound on whats in the manual I would appreciate it. Ordering a rebuild kit for an engine with a lot of letters can get kind of tricky I guess.

P=one or more connecting rod bearing journals are .010" undersize
M=All crankshaft main bearing journals are .010" undersize
PM=All crankshaft main bearing journals and one or more connecting rod bearing journals are .010" undersize.
B=all cylinder bores are .010" oversize
C=all camshaft bearing bores are .010" oversize

So you could throw in a new set of bearings even after plastigauge and and make a never been apart motor much worse. I guess the undersize is stamped on the back of the bearing shell, and all can be corrected with a reman crank kit except the cam bearings. I never knew manufactures did this, all engines I have had apart to this point if never apart were all on standard.

When you pull the caps off the rods or mains and you pull the bearings out of the caps the bearings will say what size they are.
Ex
Std. Standard
.010 - .010 oversized.
Etc.