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Re: I need to use/borrow a good bore guage]

To: Larry Colen <>
Subject: Re: I need to use/borrow a good bore guage]
From: Charles & Peggy Robinson <>
Date: Fri, 25 Aug 2006 09:42:15 -0500
   Just thought I'd point out that the Plastigage comes in a range of 
sizes. When you go to buy the stuff you need to have in mind what the 
approximate clearance will be.  Say your rod clearance is supposed to be 
.002", you buy a package of strips covering, say, .001" - .003".

   I'm with Pete on the bearing clearances.  It just depends on what the 
machinist meant by a little tight.  What kind of rod bearings are you 
putting in?



Peter Ryner wrote:
> Larry,
> The best way to check the clearance is with plastigage.  It is a thin piece
> of plastic that goes on the journal before you put the cap on.  After
> installing the cap and torquing to proper specs, the cap is taken off and
> the plastic is measured against a scale that comes with the gage.  Available
> at most auto stores.  I'm not an expert on engine tolerances, but I'd be
> concerned about using a tolerance tighter than the spec.  The tolerance is
> not just to make room for oil, it also allows proper clearance after the
> disimilar metals expand under heat.  Too tight a tollerance may cause the
> two metals to overheat causing instant meltdown of the crank.  Personally I
> would shoot for the minimun tolerance, not less.
> Pete

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