Need more clearance main bearings

I need about .0005"- .001"or so more oil clearance and was wondering if any one bearing manufacturer has bearings that run a little thinner. I have clevites now. This is for main bearings for a low deck. I did call mahle about clevite bearings being available with an extra .001". They don't make them.

I've heard that King Engine bearings run on the thinner side, but I don't have first hand experience with em

Try King bearings.Have similar issue with an RB.King makes a .001 oversize and they are on the way.They can supply many different configurations to meet your needs. Call tech department, I did. Very helpful. Bill

Thanks, I'll give them a call

Speed Pro 119M will give you about .001" more clearance than a Clevite. They are a very good bearing choice for high performance engines. And good luck finding King bearings (for BB Mopar)
in stock right now.

Brian

The 119M is for RB mains. The OP has a Low Deck.

FWIW...every set of standard size King main bearings I've tried were tighter than the equivalent Speed Pro or Clevite.

My crank is -.010 I found some -010 speed pro bearings(4094M10). I'll see what King has to offer and update.
*

Ok, so King doesn't offer a bearing with an extra .001" for a low deck. They did give me a dimension tor a standard -010 bearing thickness, so I can compare that to my clevites I already have. I'll try to update it again when I have it taken care of. thanks all.

I use that part number on most of my B motor stroker builds
I usually have more than enough clearances but I do try to have the cranks ground down to the small size on the specs for both the rod and main journals when new being finished to the customers specs

Yep, I missed that little detail. Sorry.

Brian

No mention if this is a race motor or not, or if this is a new engine to you.

Have you checked the main bores for size ?

They may be on the small side.

Race engine. Measured everything. I've already run it last year. The bearings don't look bad, but not great. I just want to loosen it a tad.

Is sending the crank out to have the mains polished an option?

Shouldn't cost much more if any than a set of bearings, especially an orphan size bearing and it eliminates the future need for an orphan size bearing.

Kevin

I wouldn't do that. Most people would not remove anymore than a tenth or so I think. Bearing manufacturers recommend to not polish crank journals, but I'm sure it's done all the time. I actually was at a shop recently to have some block work done, and brought my crank to polish. I doubt he removed enough to even measure. He used a cork belt.

I got some more bearing specs on thickness:

clevite fully grooved MS876P10 .1001 -.1006
sealed power fully grooved 4094M10 .1001-.1005
King half groove MB555HP010 .1001-.1005

So if the bearings are in spec, you'll get .0004 - .0005 variance.

Probably going to order some sealed power and see what I get.

Have you ever use red Scotchbrite pad and cleaning solvent on new bearings to increase the clearances?
I know several SO CA really good Mopar drag race engine builders that do use it to get the clearances they wanted back in the day, the trick is to not get real aggressive on using the pad, wipe it gently against the bearings shooting for a uniform finish while washing it under steady stream of solvent and then clean it thoroughly in hot soapy water and rinse it in hot clean water and blow dry it well before installing back into the bearing bores for measuring
I shoot for .0030+ on the main bearing clearances with both B and RB cranks and .0022+ on BB Chevy size rod journals and .0025+ on Mopar rod journals with 5W20Wt and 10W30 Wt. petroleum based oil, not synthetic oil
With thicker oil add more clearances

You haven't mentioned your actual clearance numbers. What are they?
Doug

Cab, I definitely thought about that. I think I will try it on a used bearing.

Rods are at .003
mains .0023 average, varies a few tenths.

I did have to buy some of the King bearings on a recent build to get a little more clearances on Chevy 383 SB Stroker motor, instead of having the crank ground down .0015

Have you measured the block itself? I'll bet the main saddles are tight. I'm assuming the the journals measure correct?
Doug

Them chevys got plenty of options.

Doug, The journals are within the FSM spec. I did measure the bores, but I couldn't find what the nominal/tolerances are. But the clearances are within what's called out in the FSM. But end of the day, I need a little more clearance. I'm not touching the crank or the main bores, so I'll find it in the bearings. Cab's idea sounds better more I think about it. I'll give it a shot tomorrow, and take a couple pics along the way.

Well got the one bearing that needed the most material removed done. I think it came out ok. Time consuming. I used 320 paper, then gray scotchbrite. I cut long strips of both and flipped the bearing around in the vice after each piece of paper to attempt to get the material removal even side to side. The clearance started at .0017, ended at .003 -.0032. First pic is the bearing in a small vice with plastic jaws

That looks great. But, i think usually you polish the actual bearing surface. Ive always polished the bearings with sovent and very fine scotchbrite. But that is effective also.

could "clearancing" the bearing that way affect the crush in the cap to block fit ?

Me too, I've never touch the back side of the bearings to get additional clearance I use laquer thinner on a clean rag and gently wipe both sides of the bearing off to remove the dust and any unseen debris off of them before installing them
Polish if needed after verifying the I.D. and clearances on them

Not sure how polishing the od has an effect on crush. From what I understand, crush is determined by how much the bearing sticks up above the cap surface. I hnow what you're getting at, but I would think the bottom of the bearing is still conforming to the bore. Worst case what I'm doing is removing .0006".

I don't know how you can evenly remove anywhere near that amount evenly from the other side of the bearing.

I feel pretty comfortable with it.