Another bearing question
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Another bearing question

  1. #1
    Senior Member lbhsbz's Avatar
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    Default Another bearing question

    I'm in the process of putting the motor back together for the new sled, and I've come across something a bit strange. I was at my machine shop today dropping off the heads...and all he had on the shelf was a set of King 3/4 groove x bearings...so I grabbed 'em to measure things up. In the #1 slot, I'm getting some strange readings. I mic'd the crank and then set my bore guage...torqued down the #1 cap after cleaning all surfaces and saw this..

    Measuring between 12 and 6 o'clock, .0036"
    Measuring between 2 and 8 o'clock, .0040"
    Measuring between 4 and 10 o'clock, .0030"

    I took everything back apart, noticed that the stampings in the backside of the shells seemed to stand a bit proud of the surface, so I cleaned that up with some 320 grit paper, reassembled and did it again.


    12 & 6: .0032
    2 & 8: .0035
    4 & 10: .0037

    WTF am I seeing here? All measurements were taken at least 3 times to verify.
    Last edited by lbhsbz; 08-10-2010 at 12:16 AM.

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  3. #2
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    Only bore that does that? How about #2?

  4. #3
    Senior Member lbhsbz's Avatar
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    #2 does something similar. I understand that the bore should get bigger as you move away from vertical, and I'm understanding that the part number stamps in the bearings are affecting this negatively which is why when I go one direction the bore gets smaller...so the before #s make sense...the after numbers are confusing. Maybe it's crushing wrong before I remove the stamping material and pulling on that other side...

    In checking things again (Dad always told me...measure twice and cut once) I'm find that if I am more than a couple degrees off on my clocking of the tool when measuring on an angle, the dimension changes amazingly fast as I approach the seem. I thought it was a more gradual slope. I guess we can ignore most of the numbers at this point, as repeatabliity without me making some tooling will be not too accurate.

    I am curious though, why would they stamp numbers in the back of the bearing AFTER they finish grind it? Why does a very light cleanup change the dimension so drastically? I marked the bearing with a fine pencil so I got within a couple degrees on my second measurements....seems almost as stupid as Bullett stamping their numbers into the front of my cam back whenever it was made.
    Last edited by lbhsbz; 08-10-2010 at 12:17 AM.

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  6. #4
    Senior Member lbhsbz's Avatar
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    LOL...shoulda checked the rear main first. Got some seriously wacked readings measuring the bearing...and the cap didn't fit as tight as I'd like, so I peened the block to clamp the cap. Peen, measure, peen measure, repeat....got the cap dead nuts centered, but still had fawked up measurements between the front half and the back half....so I pulled the bearing and measured the bore...depending on where you measure it, (front to back) there's about a 0.003" difference. It's tapered and a bit oval shaped...the cap is spread a bit and way big at the front...with the bearing, .0058" while the back is at 0.0035 or so. It's already been align honed once. The rear cap got a little hot earlier this season when it wiped out the thrust bearing cuz the driveline was about .020 to long. Oh well. anyone got a virgin block near LA?

    And I just spent about 2 hours getting all the other clearances right...#4 gave me a bit of trouble, but sanding the back of the bearing got me to .0035...sonofabitch
    Last edited by lbhsbz; 08-09-2010 at 09:58 PM.

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    Possibly whoever line honed it did not load the stones enough. And when you line hone...you need to turn the block once in a while and hone from the rear so you don't make the cap wide at the front 1/2.
    Heat shrinks the cap so the rear main failure and a shrunk cap make sense.

  8. #6
    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by Fiat48 View Post
    Possibly whoever line honed it did not load the stones enough. And when you line hone...you need to turn the block once in a while and hone from the rear so you don't make the cap wide at the front 1/2.
    Heat shrinks the cap so the rear main failure and a shrunk cap make sense.
    Yup, the line bore guy isn't my best friend, but I take full blame for current condition of the block. I built the driveline with just enough room to swing it in without pulling the pump or the motor..I wanted the most spline engagement I could get. I didnt' take into account thrust bearing deflection in the pump or hull flex, and it walked the crank forward .050 in the block. The bearing took most of it but the crank took about .008 of it...it was enough to blue the cap and block just about 1/4" forward of the rearmost thrust surface. The WOT runs from the bridge to BR RV park most of last year didn't help the matter I don't think....I flogged the dooky outta that poor motor....it's went to 9K a few times when I aired it out. It lived a good life....now I'll build a faster one.

    I need a set of .060 over 496 long rod pistons or a virgin block with a good main bore...I'm not line boring another motor. I've got another block with good mains that needs to go to .060, or I've got a good set of .030 SRPs that need a good block. It's kind of a toss up price wise...whatever I can find first I guess. Got anything laying around the shop?
    Last edited by lbhsbz; 08-09-2010 at 11:20 PM.

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    busby has a bowtie tall deck in the spam section for 850.00

  10. #8
    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by havasubyou View Post
    busby has a bowtie tall deck in the spam section for 850.00
    I piss excellence, not money....can't afford a block and pistons..one or the other. I've got another block with good mains, just the holes are too big.

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