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Old 04-05-2020, 08:20 AM   #1
walls
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Default Procedure for check bearing clearance

Would anyone have a link to or a suggestion on proper procedure for checking my bearing clearances?
I have the pan off and Iím replacing gaskets and timing/ crank gears.

The timing gear had two chips in it.

I purchased as a ďcheapĒ swap for a tired engine in my tudor.

I wanted to clear any sludge in the pan prior to install.
It was actually pretty clear.

Mustíve been rebuilt at some point.
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Old 04-05-2020, 09:38 AM   #2
Purdy Swoft
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Default Re: Procedure for check bearing clearance

No link but I use plastic gauge to measure crankshaft and rod bearing clearance . Most auto parts stores will have plastic gauge in stock . You cut off a piece of plastic gauge , put it between the crankshaft journal and the bearing and torque down the bearing cap . the plastic gauge will mash down to the present bearing clearance and give a clearance read out . Some prefer to use the aluminum foil method . Take a piece of aluminum foil about two inches by one inch and fold it double and place it between the journal and the bearing cap and torque it down to the correct ft. lbs . If the foil causes the bearing to be locked up or very tight , remove the foil and replace the bearing cap and it should be good to go . This is sort of a guess work , feel method . A person with some experience with bearing tightness feel can get by good with this method . I mostly prefer the plastic gauge method . The low cost foil is two thin to give a good feel for clearance . Its best to use the thicker more expensive foil for this test .
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Old 04-05-2020, 09:48 AM   #3
Kurt in NJ
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Default Re: Procedure for check bearing clearance

Use foil, not much need for interpretation--- and even long on the shelf foil is still good, plastigauge dries out
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Old 04-05-2020, 11:41 AM   #4
Jim Brierley
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Default Re: Procedure for check bearing clearance

I use plasti-gauge as it is by far the quickest and easiest, gives you the exact clearance on the first try. I put a drop of oil on the crank below the p-g, to hold it in place.
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Old 04-05-2020, 12:04 PM   #5
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Default Re: Procedure for check bearing clearance

My book says .001 - .0015 clearance.
Is this correct?

I’ve never used plastigauge before.
Looks like this is the one I need, yes?
Green one is .001-.003

Thanks
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Old 04-05-2020, 12:49 PM   #6
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Default Re: Procedure for check bearing clearance

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As you take out shims, the bearing surface can become elliptical. Use plastigage on more than one location on the journal. Remember, DON"T get it too tight. Better to error on the loose side than tight.
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Old 04-05-2020, 01:01 PM   #7
Purdy Swoft
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Default Re: Procedure for check bearing clearance

I agree with Eagle !!! I prefer to run mine a bit on the loose side to reduce heat and drag . I adjust mine at two thousands and this has always worked well for me .
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Old 04-05-2020, 01:12 PM   #8
Patrick L.
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Default Re: Procedure for check bearing clearance

I also use plastic-gauge and set the clearance to .0015". As said, don't use it dry, add a bit of oil and remove all the residue before finally installing the cap. Then add oil to clean journal and cap. Don't mix the caps, each has to go where it came off.
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Old 04-05-2020, 01:20 PM   #9
Merc Cruzer
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Default Re: Procedure for check bearing clearance

Quote:
Originally Posted by walls View Post
My book says .001 - .0015 clearance.
Is this correct?

Iíve never used plastigauge before.
Looks like this is the one I need, yes?
Green one is .001-.003

Thanks
For me a picture is a 1000 words.
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Old 04-05-2020, 01:42 PM   #10
Jack Shaft
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Default Re: Procedure for check bearing clearance

Whats interesting in what you are doing is there is an actual rule for shaft/babbit bearings,.001 clearance for each inch of shaft diameter..10 inch shaft?.010 oil clearance.The model a engine journal is best served by setting the bearing clearance at .0015.Using plastigage is a direct measurement.Using aluminum foil is a 'go-no go' method of measurement,use a micrometer and fold aluminum to a thickness of .002,I use a 3/4" square,install in clean bearing cap,torque..if it locks the crankshaft from turning you're good,not as precise as plastigage but will work.I use foil with the engine in the car,plastigage when its on the stand
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Old 04-06-2020, 07:11 AM   #11
Patrick L.
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Default Re: Procedure for check bearing clearance

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For me a picture is a 1000 words.




Nice pic
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Old 04-06-2020, 04:02 PM   #12
Herb Concord Ca
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Default Re: Procedure for check bearing clearance

As and add onto this post, how do you separate the shims in a shim pack?
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Old 04-06-2020, 04:27 PM   #13
walls
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Default Re: Procedure for check bearing clearance

Quote:
Originally Posted by Merc Cruzer View Post
For me a picture is a 1000 words.
Thanks, that makes it clear.
Quote:
Originally Posted by Herb Concord Ca View Post
As and add onto this post, how do you separate the shims in a shim pack?
Got me thinking, can anyone explain this, and maybe how one goes about installing a shim pack in the first place?
How does a good engine builder typically decide (or maybe they donít, is there a standard?)on shims when they rebuild?
Thanks for the help yíall
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Old 04-06-2020, 04:42 PM   #14
J Franklin
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Default Re: Procedure for check bearing clearance

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Originally Posted by Herb Concord Ca View Post
As and add onto this post, how do you separate the shims in a shim pack?
I use a razor blade
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Old 04-06-2020, 06:13 PM   #15
Patrick L.
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Default Re: Procedure for check bearing clearance

To separate the shims most use a razor blade as J mentioned. A utility knife works. If the pack doesn't want to separate as happens with me more often than not, I sand them on a sheet of glass and mic the thickness in 3 places across its length. To me, that has proven to be faster and I don't spring as many red leaks from the razor blades.

Plus, I prefer the shim packs to be the same thickness. Its probably just my anal-ness.

Last edited by Patrick L.; 04-07-2020 at 06:32 AM.
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Old 04-07-2020, 01:03 PM   #16
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Default Re: Procedure for check bearing clearance

Shims should be set when the engine is Align bored.
What I mean is
When I Align Bore the engine to size, the shims are installed.
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Old 04-07-2020, 02:04 PM   #17
Purdy Swoft
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Default Re: Procedure for check bearing clearance

I should have mentioned this in my other posts, here goes . If after checking the clearance with plasti-gauge , if the clearance isn't where you want it either add or subtract shims . In some cases when the babbit and journal look useable but the clearance is more than removing shims can correct I have filed the bearing cap just enough to give the needed clearance . Some are afraid to use such methods . This is what I would do with an older used engine . If it was an engine that had been recently rebuilt by an engine builder and it was knocking , I would send it back to the rebuilder . .In other words , If there was an early problem , rather than go into the engine myself I would expect the rebuilder to correct the problem . Ford recommended a clearance of 1.5 thousands on the new engines or engines that wasn't worn too far . I use more bearing clearance on my performance engines to reduce drag and heat . Two thousands has always worked well for me . Some prefer to allow three thousands on the rear main bearing because it is longer .

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