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Re: 1275 Midget: PCV valve

To: Trevor Boicey <tboicey@brit.ca>
Subject: Re: 1275 Midget: PCV valve
From: EMILY COWEN <ecowen@cln.etc.bc.ca>
Date: Sat, 24 May 1997 23:33:06 -0700 (PDT)
Hi Trevor Boicy!!

On Fri, 23 May 1997, Trevor Boicey wrote:

>   Well, the oil pump is constantly sucking volume out of the
> sump for one thing. The oil finds it's way back, but not
> right away, especially oil pumped up to the rockers.

I think you're confusing a dual scavajing pump dry sump system with the
"B"'s wet sump, single pump.

>   From my experience, most modern engines run with a slight
> crankcase vacuum at all times. This is of course with PCV

No Trevor, that is not possible.  There will ALWAYS be ring blow-by into
the crankcase, creating a POSITIVE pressure off-idle.  The wider the
throttle, the more blow-by.

> valves, but a PCV valve will only keep the pressure 

A pcv valve controls MANIFOLD vacuum, of which there is very little at
wot, and also less than normal with a "hot cam" at idle.

> "no higher" than the air. From whatever mechanism, it tends
> to be a bit lower than the outside, a slight vacuum.
 
See above.

>   I wish I had more technical reasoning, this is all
> observations, and a wild stab with the oil pump.

Trevor, you've never had the pleasure of driving a beater.  Those
engines don't "weep", they ooze, and drip.  The pcv valve can't keep up
with the pressure from the ring blow-by.

TTUL8r, Kirk Cowen   (who was once audited by Revenue Canada for
                      claiming oil expenses to drive from Vancouver to
                      Calgary for a convention.  11 gallons going, and 
                      9 gallons returning.  Aha says the auditor, why 
                      only 9 gallons returning??  Oh, says me, 'twas all
                      downhill coming back!!  I got the allowance.)


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