[Healeys] PVC value question

warthodson at aol.com warthodson at aol.com
Sun Dec 16 15:38:36 MST 2012


I agree that there is a larger negative pressure available by connecting the
hose to the intake manifold as opposed t the air cleaner. The question in my
mind is whether or not the increased negative pressure is necessary to handle
the blow by. It obviously would depend on the condition of the rings. As far
as I can see, eliminating the "T" fitting provides no benefit. The valve cover
is connected to the crankcase via the 12 pushrod holes in the head. And I
still do not see any benefit provided by the PCV valve.
Gary Hodson


-----Original Message-----
From: john spaur <jmsdarch at sbcglobal.net>
To: warthodson <warthodson at aol.com>
Cc: healeys <healeys at autox.team.net>
Sent: Sun, Dec 16, 2012 3:43 pm
Subject: Re: [Healeys] PVC value question


The valve alone does not do it as I understand it but the PCV loop issupposed
to. Instead of connecting the hose from the valve cover"T" to the carburetor,
a PVC valve is inserted and the hose isrouted to the intake manifold which
increases the crankcasevacuum.

John

At 03:40 PM 12/16/2012 -0500, warthodson at aol.com wrote:

If you mean thatthe valve some how does that I do not see how. The negative
pressure inthe crank case created by pulling the blow by gasses into the
intakemanifold or air cleaner is what eliminates or reduces the crankshaft
sealleakage. Assuming the negative pressure is greater that the blow by.
Gary Hodson
-----Original Message-----
From: john spaur <jmsdarch at sbcglobal.net>
To: warthodson <warthodson at aol.com>
Cc: healeys <healeys at autox.team.net>
Sent: Sun, Dec 16, 2012 1:50 pm
Subject: Re: [Healeys] PVC value question

According to a tech tip by Norman Nock the modification is meant toeliminate
the rear crankshaft seal leak by "removal of a positivecrankcase pressure to a
negative pressure".

John Spaur
San Jose, CA

At 08:20 AM 12/16/2012 -0500,warthodson at aol.com wrote:

In my opinion either locationwill provide positive crankcase ventilation. My
related question is whatpurpose does adding the valve into the PVC serve?
Gary Hodson
-----Original Message-----
From: john spaur<jmsdarch at sbcglobal.net>
To: healeys<healeys at autox.team.net>
Sent: Sat, Dec 15, 2012 6:17 pm
Subject: [Healeys] PVC value question



An article on John Sim's website shows the installation of aPVC
valve. However, the vacuum source is from the intake manifold on the
front carburetor for a tri-carb.

Why can't the vacuum source come from the rear carb air filter where
the existing crankcase ventilation hose connects?

Thank you,

John Spaur
'62 BT7
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