engine bearings

[Stangman]

So it seams I have part numbers,,,

7200CHU  .001 which seams straight forward.

7176CHB 1XL  .001  When I look it up it seams its SBC rod bearings. Am I burnt or what alittle help please

[turbohunter]

Not quite sure what you’re asking.

If you need a main bearing number
SLP-125M or SLP-125M10
Lots at Summit

What crank?

[Stangman]

Scat crank It seems the listing is weird

[turbohunter]

Rods
CLE-CB743HN

[Stangman]

Bearing pics

[turbohunter]

Is it the Chevy thing that’s throwing you?
Because the Scat crank rod journals are Chevy sized so the listings read that way.
If your deep into a thrash that may not occur to you.

[Gaugster]

Just parroting what I've heard but scat cranks have a larger radius on the journals.  This adds strength but requires a slightly more narrow bearing. Hence a part number variant. I think this applies to both rod and mains but I could be mistaken.

[turbohunter]

They are 2.200
Chevy size.
My 1UB is 2.420ish.

[Gaugster]

Yeah John they are 2.200. It’s a larger diameter.
Chevy size.

I am referring  to the radius of where the crank journal blends into the counterweight. But i guess if the bearings are intended Chevy and Scat it should be good.

[turbohunter]

Yup I was mistaken there saying it’s larger.
Middle of a thrash.

[Stangman]

Yes I know the rods are BBchevy but when i looked them up it said SBC so thats why I loaded up these pictures maybe Im missing something.

[turbohunter]

When I bought mine they were list for big AND small block. Seems odd though. I’m not a Chevy dude.
As I go back and check the PN I gave you it’s for bbc and 348/409 stuff.
But that’s the correct pn right from Jay.
I think I’m done grinding on rings for the day.

[blykins]

I usually one of the following main bearings:  FM 125M, Clevite MS1010H (for aftermarket block or with tangs sanded off for factory block), Calico coated King MB559AM.  Obviously, if you need a "ground" version of those, then you would add that to the end of the bearing:  FM125M10, MS1010H10, etc.

For rod bearings, I use:  FM 8-7200CH, Clevite CB743HN, or Calico coated Clevite CB743HN.  Same thing applies to rod bearings with sizing. 

As mentioned above, always check rod bearing to crank fillet clearance.  Check it every time, don't take anything for granted, even if it's the same combo you've used 100 times.

The part number for a SBC rod bearing is completely different and they do not interchange as the journal sizes are different.  A 2.100" journal SBC uses something like a CB663HN and a 2.000" rod journal uses something like a CB745HN.

[turbohunter]

Thanks Brent.
BTW those FM bearings Brent is quoting will show up as Speed Pro 125M. Or maybe Sealed Power.
That through me for a loop for a bit.

[Stangman]

The coated bearings whats the difference in the regular bearing coating and the black or grey coating. Is it worth getting them. Are they good for the street

[Barry_R]

The hard to find number is because that is part of a set (146M1X).
Each individual bearing shell in the set will have it's own number in the F-M system.
We often use the 351C bearing set in an FE when we need extra - or less - clearance, since F-M does not sell odd sizes for the FE.
Cleveland shells need the tang removed - or an extra slot added to use them in an FE

[Stangman]

So am I going to have a problem ordering a STD set of bearings. the 3 0r 4 i checked was that number

[turbohunter]

Why do you say that?
https://www.summitracing.com/parts/slp-125m/make/ford

https://www.summitracing.com/parts/cle-cb743hn

[Stangman]

I think he is saying they are a different size for clearance purpace

[turbohunter]

I think what he’s saying is there are different sizes IF you need them.
You have a standard Scat crank. I assume you have the normal bbc rod journals like most of us do, so ordering the bearings is pretty easy once you know the score.
If you find your crank is out of spec because you have run it, there are different sizes to bring your clearances into spec. Of course after interminable measuring (or maybe that’s just me ) and possibly work on the crank if you hurt it.

[Stangman]

Ok great thanks.

[Gaugster]

Just an FYI - Brent's got a video up on how to confirm clearances. Do your best to select the right bearing part numbers but confirm it with measurements. Might need an iteration of bearings based on those initial measurements.

https://www.youtube.com/watch?v=TRUSzF4fCt8

[Barry_R]

If we built that block it might have one or two  +.001 or -.001 bearing shells in each location to dial in clearance to our targets.

[My427stang]

I rarely have a build with a SCAT 2.20 rod journal that doesn't want a combo of std and .001

I will tell you this, I am done with FM/Speedpro bearings, no exaggeration.  I have too many sets that measure incorrectly, buying .001 that measure the same as STD, material embedded in the surface, and the icing on the cake is when I contact them I get crickets.  I have 3 sets of rod bearings in my cabinet, and they sit there, too expensive to toss LOL

Clevite and King have much more stable measurements, more options and much more readily available.  Shame too, because I like the FM/Speedpro main design, but not worth the hassle in my book anymore

[turbohunter]

I was hoping you would bring that up Ross as I’m curious. This bearing world is very interesting to me.
You and I had talked about your problems with the FM style of bearing but I got good clearance on mine. Now I have to qualify that I am nowhere near your level of expertise and have zero experience with this. But I have questions. I am almost concerned that my combo went together so easily (.0028-.0032). C’mon FE gods.
I note some builders seem to like the 3/4 groove (FM) style as it can stand the pounding of a high performance build. Would using say a Clevite full groove be that much worse off? You are obviously building some good hp. I don’t know anything about King yet as I don’t have a set here but I am soaking up any info I can as I really enjoy this and am starting to collect.

[My427stang]

I was hoping you would bring that up Ross as I’m curious. This bearing world is very interesting to me.
You and I had talked about your problems with the FM style of bearing but I got good clearance on mine. Now I have to qualify that I am nowhere near your level of expertise and have zero experience with this. But I have questions. I am almost concerned that my combo went together so easily (.0028-.0032). C’mon FE gods.
I note some builders seem to like the 3/4 groove (FM) style as it can stand the pounding of a high performance build. Would using say a Clevite full groove be that much worse off? You are obviously building some good hp. I don’t know anything about King yet as I don’t have a set here but I am soaking up any info I can as I really enjoy this and am starting to collect.

If your clearances are good, the FM bearing design is very good, so don't worry.  I have used many and when the clearance is right, it's a great bearing. However, I am not afraid of a full groove bearing in any way with proper clearances

Also keep in mind, mains can handle some clearance that I wouldn't run in a rod, especially a 2.20 journal, so I wouldn't sweat the mains, your numbers look good.  The biggest issues I have are with the 7200CH rod bearings.

Clevite, ACL, or King, take a bearing, add one half .001, you get .0005, use both, you get .001.  FM,  random clearance generators in my book, might see nothing, might be looser, might be the same, no two are alike, and I keep trying with different rod/crank pairs to get my money back out of them, but it is really just insanity that I expect some combo of crush or journal will make them accurate

I wish Speedpro would take these and look at them, especially the one with trash in the surface...but it's like yelling in a bucket.

That being said, even the 7200CH is a great bearing if your clearances come together

As far as Kings, I have used them on stock FE journals before with very good results, even the cheapest versions.  Recently Brent turned me on to coated Kings, and man they were spot on, even had a nicer thrust clearance on a SCAT 4.25 without having to massage anything.

[blykins]

Main bearing clearances are a combination of how the block was machined, how the crank was machined, and which bearing you're using. 

There's 3 variables there that have tolerances and you can easily get a tolerance stack.  It's not uncommon to see a slight swing on the crankshaft dimensions from Scat (I'm talking about .0002-.0003", nothing major) and when you get a main that a tenth or two bigger or tighter than the others plus a bearing thickness variance, you can easily see a half thou in clearance differences.   I have a full shelf set full of bearings that I stock, so I can grab bearings and try them, mix and match them, etc.  I've even used different brands of main bearings in engines to get the clearances I want.   The guy that digs into it after I'm dead and gone will probably wonder what's going on, but I'm picky about clearances.

The biggest part of engine building is knowing what works for you and then getting every piece and part to the dimensions that match what works. 

I have ran MANY main bearing clearances at .0028-.0032 and a little bit more.  If I'm running a non-coated bearing, I will normally aim for that .003" dimension on a street engine and a little more on a race engine.   

I'm building a Tunnel Port engine right now that has a steel Scat 4.125" crankshaft.  I'm using FM main bearings and Clevite rod bearings.  It came in at around .0033" on the mains and I sent them out to be coated, which should get me down at around .0027-.0028".   The rod bearings came right in at .0022" with a coated standard Clevite rod bearing, which is right where I wanted to be. 

To this date, I've been running Calico coated King main bearings, which are full grooved, on some pretty high horsepower and high rpm builds.  I've been running them at around .0025" main bearing clearance.  My 352 is closer to .002" with a Calico coated King bearing and they looked brand new upon last inspection.

[turbohunter]

Thanks guys
This is all good info for us hobbyists.

[Barry_R]

I can agree on the decline in quality control at F-M - - really irks me since that was my product line a decade or so ago and back then we took a lot of pride in those parts.

Without going into a full dissertation on bearing flow dynamics, I will say that I do not like full groove bearings at all.  You are better off with a half groove design.  The three quarter is a really good configuration as long as clearances come in well.

[turbohunter]

I can agree on the decline in quality control at F-M - - really irks me since that was my product line a decade or so ago and back then we took a lot of pride in those parts.

Without going into a full dissertation on bearing flow dynamics, I will say that I do not like full groove bearings at all.  You are better off with a half groove design.  The three quarter is a really good configuration as long as clearances come in well.

There’s the rub for us guys that don’t know all the lines well.
FM (Speed Pro) is down in quality but they have the better (qualified) design.
From my brothers dealings with Mahle I know they are picky about quality, so Clevite is appealing but they are full groove. Obviously there is a difference of opinion on the full groove vs 3/4 or 1/2.
I’m going to venture a guess that for regular hp builds (say 500) it doesn’t matter which quality bearing you choose as long as your target numbers are good. For higher hp builds the 3/4 half groove is a bigger deal.

[blykins]

I can agree on the decline in quality control at F-M - - really irks me since that was my product line a decade or so ago and back then we took a lot of pride in those parts.

Without going into a full dissertation on bearing flow dynamics, I will say that I do not like full groove bearings at all.  You are better off with a half groove design.  The three quarter is a really good configuration as long as clearances come in well.

There’s the rub for us guys that don’t know all the lines well.
FM (Speed Pro) is down in quality but they have the better (qualified) design.
From my brothers dealings with Mahle I know they are picky about quality, so Clevite is appealing but they are full groove. Obviously there is a difference of opinion on the full groove vs 3/4 or 1/2.
I’m going to venture a guess that for regular hp builds (say 500) it doesn’t matter which quality bearing you choose as long as your target numbers are good. For higher hp builds the 3/4 half groove is a bigger deal.

I've used the full groove coated bearings on a lot higher horsepower engines than 500.   When you adjust the clearances to match, I personally see no issue with them. 

[Barry_R]

The line I use is "good enough is good enough".  As long as your parts meet the needs of your application it won't matter if you have design headroom of 5% or 50%.  Means that those full groove bearings might well get the job done, but I can promise you that they are not the best design for any performance application.  Like cross drilled cranks - they work right up to the point where they don't, and then its often hard to decide where the issues lie if and when they do show up.  Some high end racing stuff is running a partial upper groove these days - under 180 - groove does not even extend to the parting line.

Think of oiling like electricity.  Oil under pressure follows the path of least resistance.  When you feed oil into the unloaded side of the bearing it does not "like" to go into the highly loaded lower shell surface.  It pursues lower resistance paths until they become saturated, where the flow area becomes a restriction that limits relief.  It bleeds out at the parting line chamfer, at the eccentricity area approaching the parting line, and around the periphery of the shell depending on clearances.  A full groove provides an additional circumference that doubles all these bleed areas into the unloaded area.  Not a full loss since its not into the sump - but a reduction none the less.  Coupled with a +/- 10-20% reduction in load bearing area for that lower shell.