<VV> (no subject)

[Mark Durham]

Lon, for #1, maybe they did both, steal a good flanged half and a extra
un-flanged half to get two sets. Or, I would presume that they had extras
in stock for each journal in case there was damage to a bearing half along
the way, so they probably had the no flange halves already and split up a
good set to make two by adding the no flange types. Production in the 60's
was organized yes, but not to the point it is today. And the quality
control systems we enjoy the benefits of today in products were in their
infancy then.

I'm sure there was a hurried call to the engineers who approved the change.

These engines do not have a lot of stress on the flanges. All the flange
does is keep the crank in position. The side loads of things like the fuel
pump  eccentric, distributor/fuel pump drive gear, and at the opposite end,
the cam to crank gears, can easily be managed by the oil layer in between
those half flanges and the crank.

Mark Durham
Hauser Idaho


On Mon, Oct 7, 2013 at 1:13 PM, lonwall at corvairunderground.com <
corvairs at pacifier.com> wrote:

> Bob - I've never heard that story before. But stranger things have
> happened in mass manufacturing.
>
> Yet it raises more questions than it answers.
>
> 1) If "stealing" a no-flange bearing half from the run was acceptable
> why not steal one of the usable full flange halfs?
>
> 2) How did the engineers know for certain that a half flange on #1 would
> be adequate. Seems like a potentially huge design change (although, like
> you said, years later we now know that it works fine)
>
> And just for fun - how did Moraine make the mistake in the first place.
> Flanged main bearings are honed as a pair. How would one half be wrong
> but not the other (or maybe entire pairs were wrong and the factory had
> to ...wait a minute that doesn't add up either.)
>
> It would be interesting to know Moraine's production schedule and how it
> matched with Tonawandas. It would seem that this "get by" move would
> have only been used for a very short period of time yet a large
> percentage of mains bearings (Moraines) pulled out of engines are half
> flange.
>
> Where does this story come from?
>
> Lon wall
> www.corvairunderground.com
>
>
> On 10/7/2013 12:29 PM, BobHelt at aol.com wrote:
> > Hi Mark,
> > Apparently you are not aware of the story, so here is a  reasonable
> repeat
> > of what happened.
> >
> > In About April 1962, the Tonawanda engine assembly plant  discovered that
> > their bearing supplier had supplied some #1 main bearings with
>  "mis-matched
> > flange" thicknesses. So production engineering studied the  situation and
> > found that those bearing couldn't be used as is, BUT production  had to
> > continue. So they issued a Tech Bulletin stating that only one half of
>  the
> > flanged bearing would be used and the other half would be the same as
> the #2  and
> > #3 main bearings. Thus, production continued until the supplier could
> supply
> >   the correct #1 bearings.This correction happened toward the end of
>  1962.
> >
> > But unfortunately, this problem and the solution got  announced to the
> > bearing industry manufacturers and suppliers. So the  bearing industry
> started
> > manufacturing replacement bearings with this  combination of half
> flanged #1.
> > The whole industry converted. And they NEVER  went back to the original
> > configuration. But Chevrolet DID. So there are STILL  many main #1s
> being made
> > and sold with the half-flange.
> >
> > The good news is that the half-flange works perfectly well. It  just
> looks
> > strange.
> >
> > HTH
> > Regards,
> > Bob Helt
> >
> >
> >
> >
> >   I fully intend to check the clearances using
> > full  flanged bearings.
> > Brian, that is all you can do. Maybe some blocks were machined
>  differently
> > for some reason and they did the half flange to prevent it from  being
> too
> > tight. Do check for that, my engine was at the inner limit with two
>  flanged
> > halves in there.
> >
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-- 
Mark Durham
Hauser, Idaho
62 Monza coupe Red/Red 4 speed