Normally, when you rebuild an Engine, you have the Machine shop
"re-size" the rods. From what I have been told, they actually mill just
a hair off of both the rod big end, and the cap, reassemble them and
then bore then to the correct size. At least thats what I have been
told. I know it sounds suspicious because it will sorten the distance
from the pin center to journal center each time this is done. Any
machine shop Folks out there care to elaborate on the actuall process
for resizing the rods?
Rich
>----------
>From: Fred Saury[SMTP:Fred.Saury(at)inforoute.cgs.fr]
>Sent: Saturday, March 08, 1997 11:10 AM
>To: W. R. Gibbons
>Cc: alpines(at)autox.team.net
>Subject: Re: S5 workshop manual...
>
>Bonjour W.R.,
>
>W. R. Gibbons wrote:
>>I don't mean to insult you, but have you mistaken inches for mm? I
>>assume the manual gives specifications in inches. An oversize of .005 mm
>>would only correspond to 0.0002 inches, which sounds very small.
>
>Yes, you are write I did a mistake, divide values by 10.
>(read 0.05 and 0.2mm instead of 0.005 and 0.02mm).
>
>
>W. R. Gibbons wrote:
>> I have not rebuilt an engine myself for 30 years, but the last time I did,
>> I used a soft plastic thread called "Plastiguage". You lay a piece of it
>> across the bearing journal on the crankshaft, tighten the rod big end,
>> then disassemble it. The smaller the bearing clearance, the more the
>> plastic thread is flattened. You compare the width of the flattened
>> thread to a chart on the package to determine the clearance.
>
>It is a good method that I will use to control clearence between
>bearings shell and crankshaft but it is not adapted to control oversize
>bearing shell.
>I know this control is strange because usualy big end bore of connecting
>rods
>is not regrinded and bearing shells are sold with standard dimensions
>for external diametre (I didn't found this dimension in my workshop
>manual).
>But in my case I am not sure of anything.
>Don't you think an oversize too important is a risk ? what is tolerence
>?
>
>
>Amicalement,
>Fred Saury from Lyon.
>Alpine V de 1966.
>
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