Greg, there is a quick and dirty method of checking bearing clearance. For
a couple of bucks you can buy Plastigage from the better auto supply houses.
This is a plastic string of known diameter. Snip off a length and place it
across the suspect journal, replace the cap and torque to specification. Do
not rotate the crank. Remove the cap. You will find the plastic has
flattened. You can then measure bearing clearance with a printed guage that
is on the Plastigage package. Note to all: This is not a precision method
to determine the exact bearing clearance, but is a damn handy way to get a
quick idea of what has happened without tearing the bottom out of the
engine.
Bill
----- Original Message -----
From: "Greg Locke" <glocke@ihug.co.nz>
To: "Alpine list" <alpines@autox.team.net>
Sent: Tuesday, March 06, 2001 6:57 PM
Subject: Fw: motor problem
> > hmmm, compression has not reduced in anyway, though maybe an oil ring
has
> > let go. I guess it is most likely the guides, hopefully not a cracked
> > piston.
> >
> > The bearings are .020. None show any sign of copper, though I guess it
> > wouldn't have to get down that far to cause a knock. Is that right?
> >
> > I am thinking of changing the bearings anyway and taking it from there.
I
> > can't be bothered pulling the motor completely to bits yet, though it is
> > pretty horrible do this job with the engine in place.
> >
> > thanks jarrid
> >
> > Greg
> >
> >
> >
> >
> >
> >
> > ----- Original Message -----
> > From: Jarrid Gross <JGross@econolite.com>
> > To: Greg Locke <glocke@ihug.co.nz>; Alpine list <alpines@autox.team.net>
> > Sent: Wednesday, 7 March 2001 12:47
> > Subject: RE: motor problem
> >
> >
> > > Greg quoth,
> > >
> > >
> > > >1725 engine with about 5000 miles on it after reboring and rebearing.
> > > >Suddenly started making a big end type knock on start up, that would
> > > >disappear as soon as oil pressure light went out. At same time, when
> > > >driving, if I pulled my foot off the accelerator, then floored it, a
> big
> > > >puff of blue smoke emits from the exhaust, and the engine pinks
wildly
> > for
> > > a
> > > >mo, then pulls fine with no smoke.
> > >
> > > Only bearing clearances will cause the big end knock.
> > > The upside down oil filter on our engines certainly doesnt help.
> > >
> > > The oil smoke is a secondary issue to the knock.
> > > Could be guides, rings or cracked piston.
> > > Compression testing might find the bad cylinder, but then
> > > again the plugs should tell the story too.
> > >
> > >
> > > Jarrid Gross
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