Minimum Bearing Crush?

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engineguyBill
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Re: Minimum Bearing Crush?

Post by engineguyBill » Mon May 28, 2018 11:56 pm

Bearing crush is pretty hard to measure accurately in the field. As BillK has mentioned in a previous post, as long as the housing bore is within the specs recommended by the bearing manufacturer, the bearing crush will take care of itself . . . . . . . .
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Re: Minimum Bearing Crush?

Post by crazy_caseys_customs » Sat Jun 09, 2018 2:47 pm

modok wrote:
Mon May 28, 2018 11:33 pm
crazy_caseys_customs wrote:
Sun May 27, 2018 10:37 pm
.....The block was line-honed, but I’m not ultra confident in the quality of the work.
.....FWIW, main bearing bore is 2.442-2.4425”.
nothing on a old ford is REALLY +/- .00025, so I read that spec, and mentally change it to 2.4420-2.2430, right away, out of habit.
The clevite bearing company does the same thing.
They specifications in the clevite catalog are OE specifications, however it is also noted in the catalog that they manufacture their bearings to what they feel is maximum crush at the minimum size. This is also true of the clearance specifications. The clearance specifications are OE, but if the bearings are a different material than OE they may in fact need different clearance than specified.
You may find this confusing, but I think it is the better way. if each company printed slightly different specifications it would result in chaos, and really when that has happened it HAS created chaos. So I think they made the right choice to keep the specifications the same as OE, even though they don't necessarily apply to the bearings they make, strange as that is, that's how it is, or rather how it has been. The future is a mystery.

BUT what about KING???? How do THEY interpret this overly precise specification? Beats me. I've had three cases where king bearings had the crush wrong, a subaru, a MG, and another that escapes me. I don't know what it means, but basically I don't trust them. If anybody does know, do tell.
I’ve had to read your reply a few times. I recently bought a Starrett dial bore gage, and while it’s certainly no Sunnen gage, it’s pretty accurate. My snap gauge measurements were surprisingly close. The main bore is 2.442” +/- a half a thousandth...I can appreciate rounding up...I’m rounding up to 2.4425”...it’s not a full thousandth outside the spec. BUT it IS on the large size of the spec for sure, though the Clevite H bearings are supposed to have nearly double the standard amount of crush. So while I may be in a situation where I don’t have the extra crush these bearings were designed to provide, I do most likely still have some, and my crush measurements, though possibly somewhat flawed in theory, back up that assumption.

FWIW, the only cap that measures outside of the 2.442” limit is #5. I’m pretty sure that you chimed in on my other post about half-shelling my mains to achieve 0.0025” oil clearance, but running two standard bearings in #5, because I was measuring 0.003” on that one. I’m still on the fence about running the extra half thou clearance on #5. My brain takes issue with that for some reason...

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Re: Minimum Bearing Crush?

Post by bentvalves » Sat Jun 09, 2018 4:15 pm

I have an engine blueprinting book in which the author states measuring bearing crush is simple -

torque main cap/rod cap into place with both bearing halves in place, release tension from one fastener, and the amount the cap springs up on that side measured with a feeler gauge is what you have for bearing crush.

not sure how accurate this is, just thought I'd toss it out there.

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Re: Minimum Bearing Crush?

Post by modok » Sat Jun 09, 2018 7:14 pm

I may have pulled a clinton and misinterpreted the word "is".

I thought you meant the specification is 2.442-2.4425”, and it measured highside to half thou over, but now I am not sure if I interpreted it correctly. Are you going to make me look it up? #-o
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Re: Minimum Bearing Crush?

Post by modok » Sat Jun 09, 2018 7:20 pm

The specification is 2.4412-2.4420 (clevite catalog)

So, I round that up to 2.4412-2.4422
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Re: Minimum Bearing Crush?

Post by midnightbluS10 » Sun Jun 10, 2018 1:33 am

crazy_caseys_customs wrote:
Mon May 28, 2018 7:33 am
modok wrote:
Mon May 28, 2018 4:36 am
I think a good press-fit, by diameter, is .001" per inch.
So, 2.4" housing.......so about .0024"
at the circumference that would be (times pie), .0076 total, or .0038 per shell

minimum? educated guess, .0006 per inch.
You accused me of “overcomplicating”...I do that. What you said falls fairly closely in line with what King published which falls fairly closely in line with what I’m measuring.

I originally got the numbers I posted from an article on Muscle Car DIY, but I’m thinking now they must have missed a zero.

https://www.musclecardiy.com/performanc ... ngs-guide/

E5084404-B0BC-41DF-A3B9-0F3402D4CEE9.jpeg

4E11C75D-DE2F-487F-81B9-FAE523300289.jpeg

So my only question/concern now, is should I be at all concerned that the main cap side has no discernible crush at all? I get that when I put the two sides together I will have crush. It just seems that the line hone must have removed more material from the cap side than the block side.

Again, thanks for thinking through this with me. I was all spun up.
Consider the source. They don't have any sort of standing. You can't trust them to be reliable because it's not a known source. It's a random website that you don't know where they got their info. Had it been race engine technology or even Hotrod, I'd value it as a trustable, at least somewhat reliable source. But that page is questionable from beginning to end, imo.

As much as I hate to make this comparison, it'd be like taking advice from me over other people here regarding valve seat angles. You don't have any idea whether I know what I'm doing but there's plenty of others here that need no proof of their intelligence and abilities. Why take my advice when you could listen to people with much more experience?


That's how I see using that website vs a known reliable source.
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Re: Minimum Bearing Crush?

Post by engineguyBill » Sun Jun 10, 2018 4:30 pm

bentvalves wrote:
Sat Jun 09, 2018 4:15 pm
I have an engine blueprinting book in which the author states measuring bearing crush is simple -

torque main cap/rod cap into place with both bearing halves in place, release tension from one fastener, and the amount the cap springs up on that side measured with a feeler gauge is what you have for bearing crush.

not sure how accurate this is, just thought I'd toss it out there.

No, not accurate at all and does not make any sense. If you torque the cap, then release the torque from one of the fasteners, and "the cap springs up" AT ALL, you have serious problems related to the caps.
Bill

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Re: Minimum Bearing Crush?

Post by clshore » Sun Jun 10, 2018 5:18 pm

Got a soft jawed clamp?
Place a bearing shell into the cap, then place the cap&shell assembly onto a crank journal.
Position the soft jawed clamp with one jaw on the back of the cap and the other jaw on the opposite side of the journal.
Apply enough clamping pressure to firmly press the assembly to the journal, seating the shell fully into the cap bore housing.
Now measure how far the shell sticks up proud of the cap mating face on both sides.
The sum of those should approximate the crush.

Of course as mentioned the parting line may not be in the dead geometric center of the bore housing.

So you can fangle a similar test with the upper shell in the block, the crank laying against the shell,
and apply a soft jawed clamping force to the crank journal to seat the shell into the block bore housing.
Measure the pop-up of the bearing on each side, sum is crush.

Add the cap measurements and the block, divide by two.

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Re: Minimum Bearing Crush?

Post by modok » Sun Jun 10, 2018 5:21 pm

Well, it does depend on the cap.
The procedure I described should work on most rods and the engine in question (if the caps are cut square), but there are many different kinds of caps which could make it impossible.
WIDE four bolt caps, or even the whole lower assembly can be one piece, in which case I would have to go by the other method described, (measuring the ID in place at partial torque VS measured housing minus bearing thickness)
At worst, a special fixture could be made to measure it, such as pictured in the illustration from KING.
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Re: Minimum Bearing Crush?

Post by Warp Speed » Sun Jun 10, 2018 5:48 pm

engineguyBill wrote:
Sun Jun 10, 2018 4:30 pm
bentvalves wrote:
Sat Jun 09, 2018 4:15 pm
I have an engine blueprinting book in which the author states measuring bearing crush is simple -

torque main cap/rod cap into place with both bearing halves in place, release tension from one fastener, and the amount the cap springs up on that side measured with a feeler gauge is what you have for bearing crush.

not sure how accurate this is, just thought I'd toss it out there.

No, not accurate at all and does not make any sense. If you torque the cap, then release the torque from one of the fasteners, and "the cap springs up" AT ALL, you have serious problems related to the caps.
That is almost exactly how you properly measure crush! It is easier to do with dowels than it is by interference registers, but that's the gist of it!

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Re: Minimum Bearing Crush?

Post by engineguyBill » Mon Jun 11, 2018 1:19 pm

As I mentioned in a previous post on this thread, make sure that the housing bores are within the specs recommended by the bearing manufacturer and the crush will take care of itself. The manufacturers generally do not publish the amount of weight (force) that they apply to the shell - not even on the assembly drawings (aka "prints") - therefore trying to measure the bearing crush is futile . . . . . .
Remember, the bearing manufacturer is your friend - trust 'em.
Bill

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Re: Minimum Bearing Crush?

Post by Warp Speed » Mon Jun 11, 2018 2:14 pm

engineguyBill wrote:
Mon Jun 11, 2018 1:19 pm
As I mentioned in a previous post on this thread, make sure that the housing bores are within the specs recommended by the bearing manufacturer and the crush will take care of itself. The manufacturers generally do not publish the amount of weight (force) that they apply to the shell - not even on the assembly drawings (aka "prints") - therefore trying to measure the bearing crush is futile . . . . . .
Remember, the bearing manufacturer is your friend - trust 'em.
Bearing manufactures never make mistakes! Hahaha

Futile........thats funny right there! Lol

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Re: Minimum Bearing Crush?

Post by cjperformance » Tue Jun 12, 2018 6:12 am

engineguyBill wrote:
Sun Jun 10, 2018 4:30 pm
bentvalves wrote:
Sat Jun 09, 2018 4:15 pm
I have an engine blueprinting book in which the author states measuring bearing crush is simple -

torque main cap/rod cap into place with both bearing halves in place, release tension from one fastener, and the amount the cap springs up on that side measured with a feeler gauge is what you have for bearing crush.

not sure how accurate this is, just thought I'd toss it out there.

No, not accurate at all and does not make any sense. If you torque the cap, then release the torque from one of the fasteners, and "the cap springs up" AT ALL, you have serious problems related to the caps.
Really? I had better recall every main I've checked crush on!
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Re: Minimum Bearing Crush?

Post by MotionMachine » Tue Jun 12, 2018 8:01 am

I don't think crush is a problem very often but I did an old Jag head recently that had about .015" crush with the new cam bearings. Dubious supplier so I re-used the old ones that had about .003" total crush.

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Re: Minimum Bearing Crush?

Post by steve cowan » Sun Jun 17, 2018 2:08 am

cjperformance wrote:
Tue Jun 12, 2018 6:12 am
engineguyBill wrote:
Sun Jun 10, 2018 4:30 pm
bentvalves wrote:
Sat Jun 09, 2018 4:15 pm
I have an engine blueprinting book in which the author states measuring bearing crush is simple -

torque main cap/rod cap into place with both bearing halves in place, release tension from one fastener, and the amount the cap springs up on that side measured with a feeler gauge is what you have for bearing crush.

not sure how accurate this is, just thought I'd toss it out there.

No, not accurate at all and does not make any sense. If you torque the cap, then release the torque from one of the fasteners, and "the cap springs up" AT ALL, you have serious problems related to the caps.
Really? I had better recall every main I've checked crush on!
[/quote
This is how I check mains as well, just checking my 383sbc with clevite bearings, come in at 0.005" average I am calling it good and now I play on, sorry guys but I don't know how to check any other way
steve c

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