Issue with main crank bearing oil clearances (searched and still need help)

I got to the point of installing the crankshaft back in the block...i got to checking the bearing oil clearances and ALL are within spec but one. The very last one. Now, i did search and per my search this is what i've done so far:

1- made sure i got the right part number, and I do: clevite 77 ms-1782p
2- Checked the stamped number on the bearings (except the thrust bearing, which is obvious) and there are two with the same number and one that is different....and the different one is supposed to go in the rear
3- measured the bearings and the largest one was also put in the rear (two are .0099 and one is .0012)

Because of what i've done im pretty sure i have the bearings in teh right place and im still getting a very low oil clearance. For all bearings i got .001 clearance which is within the .0005-.0023 required range. But for the last one im getting about .0005 when the range is .001-.0028.

The crank is standard size, it wasnt ground, it was simply polished and is still within standard size. Im stumped, any suggestions?

How are you measuring? In what shape are the old bearings in? You can either have the crank polished to the size you need or order .001 larger bearing set for the #4 main.

Hey man, thanx for your reply. Im using plastigauge to measure the clearance. You mention getting an oversized bearing for the #4 main....i wasnt aware that you could purchase a single main bearing....could i get this like at a parts store?

I never had luck getting then at a Auto Zone type place but Ford can get them for you. Also try a engine rebuild shop close to you, they can get them direct from the company with no problems. If you cant get the proper bearing then just have the #4 journal polished to the proper size.

Hold up friend, now that I think about it....i wouldnt even be able to use an oversized bearing would I? If im getting LOW oil clearance that means i need more space between the crank and the bearing for the flow of oil right? Which means going with a bigger bearing would further decrease this clearance. IF this is the case, the only thing I can do is grind down the crank for fitment unless there's an 'undersized' bearing.............or am I wrong?

CaifanSC said:

Hold up friend, now that I think about it....i wouldnt even be able to use an oversized bearing would I? If im getting LOW oil clearance that means i need more space between the crank and the bearing for the flow of oil right? Which means going with a bigger bearing would further decrease this clearance. IF this is the case, the only thing I can do is grind down the crank for fitment unless there's an 'undersized' bearing.............or am I wrong?

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I think when we're talking about bearings being oversized, we mean that they are actually larger in diameter than original. In this case, that would mean this bearing would permit more clearance between the bearing and the crankshaft journal. ...Undersized bearings would be used if you had the crank ground and needed to tighten things up as a result.

From what I hear, we should not have SC crankshafts ground. ...Polished, yes, but not ground.

I'm just starting to do the research on all this stuff, because it sounds like I spun a rod bearing about a week ago. I'm hoping things will settle down with work enough in another week or so that I can pull the engine and take a look.

Good luck!

Cheers,

Sean

Indeed, i read up on the whole crank grinding deal a while ago. Right now im using the crank from another engine b/c the one that came out of this one was damaged by a spun bearing also. I sent this one to the shop, and they told me it was good and they simply did a polish job, I specifically asked for that bc of what I read...no grind. Thats why Im surpriced that the 'standard' size bearing didnt fit in the last journal.

So at this point is my only option searching for an oversized bearing and testing it out?