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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: "Peter Ryner" <>
Date: Wed, 23 Aug 2006 07:53:10 -0400
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.

-----Original Message-----
From: []On
Behalf Of Larry Colen
Sent: Wednesday, August 23, 2006 4:56 AM
Subject: I need to use/borrow a good bore guage]

I'm totally stoked, because I think that I finally have all of the
parts I need to put Jasmine's motor back together.

When Armando did my crank, he machined the rod journals to tighter
than stock tolerance, and told me to use thinner oil. The premise
being that with the blower, the tighter tolerances will allow less
room for the rods to pound on the crank.

When I went to measure the clearances at my previous machine shop,
Gary's bore guage didn't have ball bearings at the ends and it seemed
to scratch the rod bearing and give inaccurate results (we're trying
to measure to lessn a thou, so any scratch in the soft bearing
will screw things up).

Don (my current machinist) has a bore guage, but won't let anyone but
himself (not even employees) touch it, and he doesn't have time for a
while. So, is there anyone relatively near Santa Cruz with a decent
bore guage I can use to check my bearing clearances?

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