Fwd: <VV> OIL PRESSURE

[James Davis]

I guess I have all the worn Corvair blocks. Trying to find pieces for 
two big bore engine this spring, I checked nine sets block halves 
(yes I kept the half together with small hose clamps on the facing 
studs).  I find the big bearing wears most as it is the farthest from 
the oil pump and takes the entire gear mesh load.  The big cam 
bearing size is 1.440 inches so I set my dial bore gauge to that. The 
best showed 1.460 with 0.006 out of round.  Five of the blocks were 
1.482 with an out of round of 0.0011 or more.  One was 1.484 with an 
out of round of 0.024.  I find if the cam bearing clearances are 
greater than 0.003 that you cannot maintain 10 psi of oil pressure at 
600 rpm with 250 F oil temp and 10W-30 oil even it the crank bearings 
are set tight.
Jim Davis




At 01:13 PM 5/22/2006, HallGrenn at aol.com wrote:
>In a message dated 5/19/2006 12:43:04 PM Eastern Daylight Time, ronh at owt.com
>writes:
>
> > think you are writing about when it was new.  Now with worn cam bearings
> > it could well be giving you close to zero psi at idle.
> > RonH
>
>Ron brings up a question I have always wondered about--the block cam bearing
>area (no real bearings of course, just the block itself where it supports the
>cam.  Outside of checking tolerances when an engine is apart I have never had
>to reject a crankcase because of wear at the cam bearing area.  I have always
>changed oil regularily and all of my engines have high mileage with good oil
>pressure.
>
>What is the experience of other VVers with crankcase wear at the cam bearing
>area?  With age and high mileage when can one expect to have an out of
>tolerance crankcase (or half)?
>
>Bob Hall
>Group Corvair
>'64 Brier
>'65 Corsa
>2 '68 Monzas
>
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