imariver

Is there some sort of "Rule-Of-Thumb" when selecting a new PCV valve?
What determines, the correct PCV valve to use for any particular application?
Thanks . . . .

NewbVetteGuy

Following...

resdoggie

Go to your parts store and buy the pcv listed for your car.

calwldlife

interesting, but it boils down
to engine size/type and then any angle on the
fitting and diameter for the grommet.

MelWff

your profile says you have a stock 1973 350 so just buy the stock PCV

HeadsU.P.

I believe they are in inches of vacuum catagories. If your engine is modified (cam, etc) a stock unit may not work. A stock engine might have had 22" of vacuum but now has 10" of vacuum due to long duration cam. Obviously the original PCV valve will do nothing.
How you order the proper unit, I do not know. Few parts counter people know what you you need. But you can start by recording vac at idle and go from there.

imariver

Exactly . . . All I know, at this point is the vacuum at idle, which is 10/11" in this new crate motor. The PCV valve I'm using now, is one for an L-48 with 18/19" Somebody out there must know the parameters for picking the right valve, or at least I think . . . . .

HeadsU.P.

As far as diameter to fit in the grommet, I believe most are the same size. There must be a chart somewhere that shows part number and vacuum in inches required to open / operate the valve. Parts counter people only know VIN, Yr, make, model. Not much help for modified mills. Maybe try a Google search for PCV Valve stats.

roscobbc

Go buy one of those adjustable PCV valves - 'tweak' it until you get the optimum vacuum for your engine...

calwldlife

i understood your question.
here
http://www.engineprofessional.com/ar...Q315_34-44.pdf

calwldlife

as far as grommet, sure for cheby v8s
you may need a late model
different maker valve.

Sayfoo

Here's a informative article. Disregard the sales pitch.
http://mewagner.com/wp-content/uploa...015-p34_44.pdf

My only thought is to use the stock part if you have a stock engine, or, see if there is/was a higher performance engine available for your car. Are they different part #'s ??.
I know that there are different part #'s for small blocks and big blocks.

Another interesting link
http://www.teamlucor.com/stores/gene...%20Catalog.pdf

TPI BOY

Great link

SteveG75

I tried several different PCV valves for my 496 BBC. My EFI is so sensitive that I can track the effects of the different valves by how open the IAC valve is at idle.

There is actually a code stamped on the AC Delco valves that describes both flow and spring strength. The auto parts store valves could be all over the map.

I ended up with the ME Wagner valve and used an oil catch can from Jegs. Works very well.

SteveG75

Good discussion in this old thread:
https://www.corvetteforum.com/forums...eded-lars.html

I tried all the valves listed in that thread plus the stock 427/435 valve in my 496 BBC. Like I said, ended up with the ME Wagner and it works great.

imariver

Never heard of an adjustable PCV valve.

MelWff

PCV used on L-88 and LT-1, AC 746C

SteveG75

The 746C was mentioned in that link I posted. Like I said, I could actually see the IAC behave differently with different valves. I like the ME Wagner adjustable valve. I am getting good flow based on the amount of oil in my catch can.