BBC rod bearing clearance

[Bishop540]

My Eagle 4.25 stroker crank and Clevite bearings are a little on the tight side -but within GM specs, mainly the rods at .015. So I ordered a .001 King bearing and was just hoping that King's oversize wont be over .030 installed. I didn't think about it first, but King's Standard bearing may have been closer to a normal .002+, rather than Clevites Standard at .015 in my BBC.

Is there that much difference between the 2 name brands of the same size? I'm gonna find out, but was just wondering?

[Baprace]

My Eagle 4.25 stroker crank and Clevite bearings are a little on the tight side -but within GM specs, mainly the rods at .015. So I ordered a .001 King bearing and was just hoping that King's oversize wont be over .030 installed. I didn't think about it first, but King's Standard bearing may have been closer to a normal .002+, rather than Clevites Standard at .015 in my BBC.

Is there that much difference between the 2 name brands of the same size? I'm gonna find out, but was just wondering?

I think you are using the wrong dimensions, your rods are at .0015 NOT .015 , make sure you tell your supplier you want .001 more clearance bearings, they should be close to .0025 if your numbers are correct, a little bit more or less is not a big issue on a BBC engine, that .0025 would be nice for a performance engine.

[Bishop540]

My Eagle 4.25 stroker crank and Clevite bearings are a little on the tight side -but within GM specs, mainly the rods at .015. So I ordered a .001 King bearing and was just hoping that King's oversize wont be over .030 installed. I didn't think about it first, but King's Standard bearing may have been closer to a normal .002+, rather than Clevites Standard at .015 in my BBC.

Is there that much difference between the 2 name brands of the same size? I'm gonna find out, but was just wondering?

I think you are using the wrong dimensions, your rods are at .0015 NOT .015 , make sure you tell your supplier you want .001 more clearance bearings, they should be close to .0025 if your numbers are correct, a little bit more or less is not a big issue on a BBC engine, that .0025 would be nice for a performance engine.

Yeah yeah, tomatoe tomato. It been a long day.

My point is that I am replacing Clevite Standard with King .001 "X" bearings. And I'm hoping for no more than .0025 with the change to a different manufacture.

Thanks for your reply!

[FC-Pilot]

I have seen 3 or 4 different times where putting a king HP bearing in when I had measured a Clevite H series of the same size did end up opening up the clearance. The first time I saw it I thought I screwed something up and put the Clevites back in and measured them again. Being at .0015 I don't thing the Kings will be a bad choice. When dealing with overseas cranks I almost always have to use .001X bearings.

Paul

[pamotorman]

this is why you must measure every time you make a change. you can not take a size change for granted

[SupStk]

Yeah, measure and be sure. Its when a person assumes is when things go sideways.
Shoot for .0025 on the rods and that BBC will live a long and happy life.

[engineguyBill]

In most cases, the sizing between Clevite and King engine bearings is pretty consistent. In other words, if you measured .0015" with STD Clevite bearing, then you should come up with .0025" with the King 'X' series bearing. One word of caution however: Eagle cranks are not known for having consistent journal diameters, so you really should measure each bearing/journal.

[Bishop540]

My Eagle 4.25 stroker crank and Clevite bearings are a little on the tight side -but within GM specs, mainly the rods at .0015. So I ordered a .001 King bearing and was just hoping that King's oversize wont be over .0030 installed. I didn't think about it first, but King's Standard bearing may have been closer to a normal .002+, rather than Clevites Standard at .0015 in my BBC.

A year latter and I am just now getting back to this project: I bought the King .001 bearings but it looks as if I only gained .005 more clearance and not the full point I was after. I don't know why I was expecting a full .001 with the "x" bearing. I didn't snap that I was only gonna get a half instead of the full one. So in the future I will either have to order a .002 extra clearance bearing (which i doubt they make) or buy only 8 half shells that will give me a full point......

Am I seeing this correctly? Or does the "x" bearing mean I will actually get an extra .001 from each half shell, taking my previous clearance from .0015 to .0025? In this instance I only increased from .0015 to .0020. But I did change from Clevite to King with the "x".

(hope this isn't confusing, its the best way i know how to explain it). Thanks!

[BillK]

Eric,
The "X" bearings "should" have given you an additional .001" clearance. That being said, I have found lately that the King bearings are very inconsistent as far as size goes. I dont use them unless they have something that Clevite does not offer. If you had .0015" with the Clevite bearings why don't you just get the Clevite "X" bearings ? I would bet that would put you closer to .0025"

Also like the others mentioned earlier you really have to measure each and every journal. Pay attention to the taper and also the size right at the edge of the journal right before the radius starts.

[Ted Gerstenslager]

Each 1/2 shell will usually net .0005 Most times you mix and match with std and .001 or HX to get desired clearances. Sometimes you can't.
Eagle was very inconsistent in the past, with journal taper toward the fillet, as in getting larger.
Not dressing the wheels routinely or properly.
Strive for .0027-.0028 and it will live a happy life, with .0025 absolute minimium.
Sometimes you just have to cut the crank to get things to work. This is called stacking tolerance, crank is on spec but on the high side, and rods are on spec and on the low side.

[A_VAS]

I would carefully read the p/n of the King bearings you have, and check the manufacturers description

the King XP bearing sets do typically come 'looser' than the Clevite H series if you compare STD set to STD set

A King XP set with 001 after the p/n is actually a .001 undersize (tighter clearance) bearing. Bearing shell is thicker in other words
The King set in XPN might be right on
XPNX would be .001 looser fit to the crank
XPN001 is .001 tighter

[Newold1]

X3 what the two Bill's are saying here. Eagle (Chinese) crankshaft journal are almost always + or - .001" every time they are produced and measured!

Not checking the journal diameters individually will give you clearances all over the place!

This is part of what "blueprinting" is all about! "When in doubt, check it out!"

[Bishop540]

I am installing the pistons today and havent 100% decided which bearings to use. All the crank journals measure a close 2.200. With the Clevite standard bearings the rod halves measure 2.202. With the .001X King bearing it measures a close 2.203 on all rods. Is .003 going to be too much rod bearing clearance for this street 492 BBC?

[Warp Speed]

How are you checking clearance?

[Bishop540]

I am doing it with my only tool: dial caliper. But my original measurement was from the machine shop who said they were .0017-ish. He has all those fancy tools for measuring. Measuring with my dial caliper, I measured .002. So I assumed I can easily be .0003 off his measurement.

I had also used plastigage at one point and it was tight (.0015 range) with the original Clevites, his .0017 measurement.

With the new King .001X, I measure .003 with my dial indicator but havent taken it to him -those guys are always too busy.

The attached picture was a plastigage I did with the new King X. But it wasnt a pretty test. Not sure why the plastigage didn't flatten in the middle. ????