I have no idea what would push the PCV piston back off the seat
without a spring strong enough to open it a against low vacuum:
http://members.rennlist.com/pbanders/PCV.htm
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

RCSnyder wrote:
>
> Bill,
>
> I must beg to differ.
>
> I have purchased two very different replacement SB PCV valves wearing the
> same Fram part number and the difference between them was one had a spring
> and the other did not. The one without the spring rattles like a baby's toy
> at idle while the one with the spring is hardly noticable. I tossed the
> baby rattle for the same reason as did JRK58.
>
> Fram apparently does not consider the presence of the spring as required for
> proper operation of the PCV circuit in a Mopar SB, nor do based on my
> understanding of the valve's operation.
>
> For those who are unfamiliar with the related airflow process, I pulled this
> from http://autorepair.about.com/library/faqs/bl102b.htm
>
> "The theory behind PCV operation is this, A hose from the intake manifold
> goes to the PCV valve. The PCV valve usually sits in the top of the valve
> cover. Then another hose comes from the air filter housing, either from the
> inside of the air filter or through a breather filter, and to the crankcase.
> Now when the engine is running air is drawn from the air filter housing into
> the crankcase, through the PCV and into the intake. So there is a vacuum
> inside the crankcase."
>
> It would appear that the rather upright orientation of the valve when
> installed in a SB valve cover allows the valve weight to provide enough
> closing pressure keep the air flowing the proper direction while maintain
> the required amount of manifold vacuum. Contrary to your statement, the
> spring's purpose is not to open the valve at low throttle but to keep it
> closed until vacuum pulls it open so that a certain amount of manifold
> vacuum is maintained at all times.
>
> Think about the importance of maintaining manifold vacuum. Power brakes
> would be without assist, vacuum spark advance curcuits would be neutered
> along with many emission control systems. Fortunately PCV valves gum up
> more often than stick open making their failure less noticable. Poor fuel
> mileage and a black exhaust pipe would be good things to watch for in a more
> modern engine.
>
> Hope this helps.
>
> Bob

 

I have no idea what would push the PCV piston back off the seat
without a spring strong enough to open it a against low vacuum:
http://members.rennlist.com/pbanders/PCV.htm
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

RCSnyder wrote:
>
> Bill,
>
> I must beg to differ.
>
> I have purchased two very different replacement SB PCV valves wearing the
> same Fram part number and the difference between them was one had a spring
> and the other did not. The one without the spring rattles like a baby's toy
> at idle while the one with the spring is hardly noticable. I tossed the
> baby rattle for the same reason as did JRK58.
>
> Fram apparently does not consider the presence of the spring as required for
> proper operation of the PCV circuit in a Mopar SB, nor do based on my
> understanding of the valve's operation.
>
> For those who are unfamiliar with the related airflow process, I pulled this
> from http://autorepair.about.com/library/faqs/bl102b.htm
>
> "The theory behind PCV operation is this, A hose from the intake manifold
> goes to the PCV valve. The PCV valve usually sits in the top of the valve
> cover. Then another hose comes from the air filter housing, either from the
> inside of the air filter or through a breather filter, and to the crankcase.
> Now when the engine is running air is drawn from the air filter housing into
> the crankcase, through the PCV and into the intake. So there is a vacuum
> inside the crankcase."
>
> It would appear that the rather upright orientation of the valve when
> installed in a SB valve cover allows the valve weight to provide enough
> closing pressure keep the air flowing the proper direction while maintain
> the required amount of manifold vacuum. Contrary to your statement, the
> spring's purpose is not to open the valve at low throttle but to keep it
> closed until vacuum pulls it open so that a certain amount of manifold
> vacuum is maintained at all times.
>
> Think about the importance of maintaining manifold vacuum. Power brakes
> would be without assist, vacuum spark advance curcuits would be neutered
> along with many emission control systems. Fortunately PCV valves gum up
> more often than stick open making their failure less noticable. Poor fuel
> mileage and a black exhaust pipe would be good things to watch for in a more
> modern engine.
>
> Hope this helps.
>
> Bob

 

L.W. ("ßill") ------ III did pass the time by typing:
> I have no idea what would push the PCV piston back off the seat
> without a spring strong enough to open it a against low vacuum:
> http://members.rennlist.com/pbanders/PCV.htm

In all my dealings with those doodads I've come to the realization
that those without springs are simply rejects that made it though.
And that 99% of the time a spray or three of carb cleaner will make
the old one just like new again. It's that cracked O-thingy they
fit into that needs to be checked and replaced every now and then too.

--
DougW

 

L.W. ("ßill") ------ III did pass the time by typing:
> I have no idea what would push the PCV piston back off the seat
> without a spring strong enough to open it a against low vacuum:
> http://members.rennlist.com/pbanders/PCV.htm

In all my dealings with those doodads I've come to the realization
that those without springs are simply rejects that made it though.
And that 99% of the time a spray or three of carb cleaner will make
the old one just like new again. It's that cracked O-thingy they
fit into that needs to be checked and replaced every now and then too.

--
DougW

 

L.W. ("ßill") ------ III did pass the time by typing:
> I have no idea what would push the PCV piston back off the seat
> without a spring strong enough to open it a against low vacuum:
> http://members.rennlist.com/pbanders/PCV.htm

In all my dealings with those doodads I've come to the realization
that those without springs are simply rejects that made it though.
And that 99% of the time a spray or three of carb cleaner will make
the old one just like new again. It's that cracked O-thingy they
fit into that needs to be checked and replaced every now and then too.

--
DougW

 

Hi Doug,
In the old days when our oil, gasoline, and engine temperatures
didn't handle the condensation as well that spring would just rust away
and disappear. My PCV spring is find with the gasolines I use in my
Bronco with three hundred thousand. If I'm doing the carburetor I'll
drop it in the tank, too.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> In all my dealings with those doodads I've come to the realization
> that those without springs are simply rejects that made it though.
> And that 99% of the time a spray or three of carb cleaner will make
> the old one just like new again. It's that cracked O-thingy they
> fit into that needs to be checked and replaced every now and then too.
>
> --
> DougW

 

Hi Doug,
In the old days when our oil, gasoline, and engine temperatures
didn't handle the condensation as well that spring would just rust away
and disappear. My PCV spring is find with the gasolines I use in my
Bronco with three hundred thousand. If I'm doing the carburetor I'll
drop it in the tank, too.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> In all my dealings with those doodads I've come to the realization
> that those without springs are simply rejects that made it though.
> And that 99% of the time a spray or three of carb cleaner will make
> the old one just like new again. It's that cracked O-thingy they
> fit into that needs to be checked and replaced every now and then too.
>
> --
> DougW

 

Hi Doug,
In the old days when our oil, gasoline, and engine temperatures
didn't handle the condensation as well that spring would just rust away
and disappear. My PCV spring is find with the gasolines I use in my
Bronco with three hundred thousand. If I'm doing the carburetor I'll
drop it in the tank, too.
God Bless America, Bill O|||||||O
mailto:-------------------- http://www.----------.com/

DougW wrote:
>
> In all my dealings with those doodads I've come to the realization
> that those without springs are simply rejects that made it though.
> And that 99% of the time a spray or three of carb cleaner will make
> the old one just like new again. It's that cracked O-thingy they
> fit into that needs to be checked and replaced every now and then too.
>
> --
> DougW