<VV> Engine building - bearing clearance

[corvair at mts.net]

I am measuring the inside of the bearing bore in a torqued block, using snap gauges and a micrometer.

I measure the crank, the journal is (for example, and from memory) 2.0985". I measure the corresponding bore with snap gauge (.001 shells installed), then mike the gauge, and get 2.0991".

So my clearance is .0006 - too small.

I want .0010 more clearance, so I substitute 2 STD shells instead of .001 shells.

Remeasure, and now the bore measures 2.1011 and clearance is .0026" (pretty big).

That's what makes me think that a single .001 shell takes away .001 clearance and a pair of them takes away .002.

It's confusing me. Assembling with plastigauge will assuage my concerns.

Les

> 
> From: "Harry Yarnell" <hyarnell1 at earthlink.net>
> Date: 2010/01/21 Thu PM 02:37:08 CST
> To: <corvair at mts.net>, 
> 	<bobhelt at aol.com>, 
> 	<virtualvairs at corvair.org>
> Subject: Re: Re: <VV> Engine building - bearing clearance
> 
> What  are you measuring with? Plasticgage is the only way I know of. 
> Measuring with mechanical calipers gets you close for the crank. Forget 
> about measuring the bearings with calipers...
> 
> 
> Harry Yarnell
> Perryman Garage and Orphanage
> hyarnell1 at earthlink.net
> ----- Original Message ----- 
> From: <corvair at mts.net>
> To: "Harry Yarnell" <hyarnell1 at earthlink.net>; <bobhelt at aol.com>; 
> <virtualvairs at corvair.org>
> Sent: Thursday, January 21, 2010 3:08 PM
> Subject: Re: Re: <VV> Engine building - bearing clearance
> 
> 
> > That's what I thought too, and it's why I'm scratching my head. It's hard 
> > to measure the thickness of the bearing to know for sure.
> >
> > I swap ONE shell, and my clearances are good - added .001 by swapping one 
> > shell.
> >
> > I will plastigauge as a last step but this is confusing me.
> >
> > Les
> >>
> >> From: "Harry Yarnell" <hyarnell1 at earthlink.net>
> >> Date: 2010/01/21 Thu PM 01:56:59 CST
> >> To: <corvair at mts.net>,
> >> <bobhelt at aol.com>,
> >> <virtualvairs at corvair.org>
> >> Subject: Re: <VV> Engine building - bearing clearance
> >>
> >> I thought that a .001 undersize bearing was the TOTAL, not .001 for each
> >> shell .
> >>
> >> Harry Yarnell
> >> Perryman Garage and Orphanage
> >> hyarnell1 at earthlink.net
> >> ----- Original Message ----- >
> >> > Am I correct that a .001 US bearing is supposed to take away .001
> >> > clearance for EACH bearing shell (.002 total if you use one on each 
> >> > side)?
> >> > That's what my measuring looks like.
> >> >
> >> > I have a nice .0010-.0016 across all four bearings now, all .001 except
> >> > for 1 side STD in #2 and 1 side STD in #4.
> >> >
> >>
> >>
> >
> > 
> 
>