[Chevelle-list] valve tap ?

[Rick Schaefer]

Thanx for the detailed explaination. I've been changing PVC Valves for 30
years and never really knew what they do.

On 6/30/07, tech <granitecityperformance at charter.net> wrote:
>
>  The PCV valve (positive crankcase ventilation) is designed to remove the
> harmful blow-by gases in the crankcase. The PCV valve is designed to
> have "variable flow" which uses manifold vacuum to draw crankcase vapors
> into the intake manifold.  During idle, manifold vacuum is very high and
> blow-by pressure is very low - the pintle inside the valve will retract
> against a spring and only allow a small amount of blow-by to enter the
> manifold.  If the spring pressure is nearly equal to the force on the valve
> from the vacuum the pintle will bounce and make a rattling sound.  This can
> happen if there is low manifold vacuum at idle due to a long duration
> camshaft or late ignition timing - or the spring in the valve wore out.
>
> Replace the valve.  You'll pay around $3.00.
>
>    <http://www.granitecityperformance.com/> Granite City Performance
> custom engineered competition components
>
>
>
>  ------------------------------
> *From:* chevelle-list-bounces at chevelles.net [mailto:
> chevelle-list-bounces at chevelles.net] *On Behalf Of *Jim & Chris
> *Sent:* Friday, June 29, 2007 11:04 PM
> *To:* Chevelle Forum
> *Subject:* [Chevelle-list] valve tap ?
>
>
>  *I have what sounded like a valve tap,and when I touched the valve cover
> it felt like a rocker arm was tapping against it so I snugged the rockers ,
> replaced the valve cover and started the motor it was less noisy . when I
> looked closer I noticed the PCV valve that I had not plugged back in was
> making the tapping noise. I disconnected the PVC from the vacuum hose while
> the car was still running,when I put my thumb over the vacuum hose I noticed
> the vacuum was intermittent causing the PVC to make the tapping noise. What
> would cause the vacuum to fluctuate so rapidly ? I was using the vacuum port
> on the back of the carborator for the PVC. sorry about running on.anyadvice is appreciated. Jimmy C.
> *
>



-- 
Rick Schaefer
72 TPI El Camino
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