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post #1 of 22 (permalink) Old May 3rd, 11, 10:08 PM Thread Starter
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Matt
 
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Main bearing question

I am putting a 406 together and am using one half shell of a P bearing and one half shell of an HX bearing .001 oversized. The HX bearing has the oil groove continue partly into the lower shell. The P bearing only has the oil groove in the top half of the shell.

My question is should I use the bottom half of the P and top half of the HX and only have an oil groove in the top half of the bearing? Or should I use the bottom half of the HX and the top half of the P and have the oil groove continue a little into the bottom half of the main bearing?

Thanks for any advice.

Matt

Matt
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post #2 of 22 (permalink) Old May 3rd, 11, 10:23 PM
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darrell
 
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Re: Main bearing question

i wouldnt seperate them--i have used the p bearing like that in 700-800hp with no problem--just saying in my opinion
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post #3 of 22 (permalink) Old May 3rd, 11, 10:24 PM
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Re: Main bearing question

the p and h bearing is different i accordance with the crank if its been chamferd or not
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post #4 of 22 (permalink) Old May 3rd, 11, 10:42 PM Thread Starter
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Matt
 
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Re: Main bearing question

The P bearings are standard size. I needed a little more clearance so I got .001 over bearings but they were only available in the H bearings. I wanted .0005 more clearance so that is why I am using one halve of the P and the other have of the H to get .0005 more clearance. I just have to decide if I want the oil groove to continue a little into the lower half or not. That will tell me which half of the P to use and which half of the H to use.

Matt
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post #5 of 22 (permalink) Old May 3rd, 11, 11:08 PM
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darrell
 
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Re: Main bearing question

i just wouldnt do that --thats me--the h bearing has the roll lip on the edge and p doesnt - i think--i know its that way on rods----i am perty picky on my measure ments too and i use more clearance on my back main than rest--but i install my bearings measure and tell machine shop where i want it--cant help u any further on trying that
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post #6 of 22 (permalink) Old May 4th, 11, 05:52 AM
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Re: Main bearing question

Quote:
Originally Posted by MW67RS View Post
I am putting a 406 together and am using one half shell of a P bearing and one half shell of an HX bearing .001 oversized. The HX bearing has the oil groove continue partly into the lower shell. The P bearing only has the oil groove in the top half of the shell.

My question is should I use the bottom half of the P and top half of the HX and only have an oil groove in the top half of the bearing? Or should I use the bottom half of the HX and the top half of the P and have the oil groove continue a little into the bottom half of the main bearing?

Thanks for any advice.

Matt

Just get a set of HX coated!!!
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post #7 of 22 (permalink) Old May 4th, 11, 09:20 AM
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Re: Main bearing question

-

Last edited by secndgn; May 4th, 11 at 09:52 AM.
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post #8 of 22 (permalink) Old May 4th, 11, 01:13 PM
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Sean
 
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Re: Main bearing question

I wouldn't do that either, I'm pretty sure there is a difference in the bearing hardness as well as the other items pointed out. Either way I wouldn't use two different types of shells on the same journal.
What clearance are you shooting for?

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

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post #9 of 22 (permalink) Old May 4th, 11, 05:39 PM
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Re: Main bearing question

I think CNC is saying to use the HX coated for upper and lower as a set, HX is a .001 oversize and the coating reduces that to .0005.

MW67RS want to get .0005 more clearance.
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post #10 of 22 (permalink) Old May 4th, 11, 06:41 PM
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Sean
 
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Re: Main bearing question

Quote:
Originally Posted by secndgn View Post
I think CNC is saying to use the HX coated for upper and lower as a set, HX is a .001 oversize and the coating reduces that to .0005.

MW67RS want to get .0005 more clearance.
If this is in reference to my reply I meant I wouldn't mix bearings. I agree with Carl (cnc) just get the right bearings. I wasn't very clear with my reply probably.
My question regarding clearance was wondering what he was ultimately shooting for. If he's worried about 5 thou I would say err on loose as opposed to mixing bearing types like that, but ultimately it depends on the rpm range and use of the motor.

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #11 of 22 (permalink) Old May 4th, 11, 08:23 PM
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Re: Main bearing question

Is there a problem with using the same type/style to reduce clearance? Ex. STD HN with a under size .001 HN to close up the clearance by .0005
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post #12 of 22 (permalink) Old May 5th, 11, 07:10 AM Thread Starter
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Matt
 
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Re: Main bearing question

Thanks for the info. My machine shop told me it was alright to use the P and HX bearings together on the same main. So I called Clevite and they agreed with you guys. They said the H bearing is harder than the P bearing and using them together on the same journal will not give the proper crush.

I asked about the HXK coated bearings. They said the coating will reduce the clearance by .0002 - .0004" per journal. I think this will give to much clearance.

Damn. I guess I have to buy a 3rd set of bearing. I just put the crank into the block for final assembly yesterday. Got to start over now.

Thanks again for the info. Without it I would have put it together wrong.

Matt

Matt
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post #13 of 22 (permalink) Old May 5th, 11, 09:35 AM Thread Starter
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Matt
 
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Re: Main bearing question

Secndgn,

Clevite said that what you are talking about is fine. Just can't mix P and H types.

Matt
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post #14 of 22 (permalink) Old May 5th, 11, 12:53 PM
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Sean
 
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Re: Main bearing question

Out of curiosity what clearances are you shooting for, and what are they currently?

Sean

1968 rs with an old school 354" SB2.2 pump gas motor.

Repetition does not transform a lie into a truth.

Franklin D. Roosevelt
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post #15 of 22 (permalink) Old May 5th, 11, 05:06 PM Thread Starter
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Matt
 
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Re: Main bearing question

Sean,

With the P bearings I was getting .0022 to .0024. Using one half of the HX with one half of the P, I am getting .0026 to .0029. My rear main with the P bearing has .0036 clearance. I was told by the machine shop to target .0028 clearance.

I ordered a set of H standard bearings and a set of H1 bearings that are .001 tighter clearance than the H. I think with H bearings in standard and .001 over and under sized I should be able to get all the clearances where I need them.

Matt

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