PCV Valve and idle A/F ratio
 

I read in a forum that many carbs are designed to get a good idle with the PCV Valve hooked up and if it isn't hooked the idle mixture came rich. Is it true? applies for a Carter AFB 9605S?

Thanks :)

if my brain is working better than normal. i think chrysler started using PCV valves in 1963, on all engines. i think. before that they had tube that came from the back of the engine drawing air from the crankcase and going down just below the bottom of the engine. cut at an angle to put a draw on the tube. a OPEN tube with a small chamber with what we called horse hair. NOT a real filter. engine life? not good. the PCV valve helped engine life tons. OH your point. yes if the carb is made for a PCV valve DO use one. the PCV valve does need to be replaced from time to time.

I'm interested in the theory behind this. I always thought that as long as you capped the port on the carb (vacuum leak) and switched to breathers you'd be golden. Good topic.

Newer engines have 2?
 

Why do some of the newer fuel injected motors have one on each valve cover? Is it necessary to hook up both of these? I have done a 360 Magnum topped with an intake and carb conversion on an old truck... Do I need to hook up both PCV's to the carb? Can I put a filter style in one and run a tube for the other... or perhaps tee them together?

PCV is just what it is "Positive Crankcase Ventilation" Nothing more and nothing less......
It's purpose is to draw out combustible fumes that get past the piston rings into the crankcase.

Do you "Have" to have it??????? No...
Is it good for a healthy long life for your daily driver..... Yes

Hope this help Y'all
:)

Of COURSE it affects idle. Any carb mixture I've seen has enough range to adjust. I would NOT run without PCV. The alternative is oil leaking from gaskets from crankcase pressure, and oil mist and smell blown all over the engine compartment (eventually)

Well so here is other question. How to choose the pcv valve? I read that it must be choosen according to the engine horse power curve

You can just order an OEM replacement..
I dont think your making enough H.P. to worry about it? Are you?

i looked at how a PCV valve works. if i am right it is made to pass a cretin amount of air. but NOT to much. it has a spring that closes down a little at high air flows. like my buddy's said if it rattles it is most likely good. but some people replace them every so many years, just to be sure. once i had an extension tube on my valve cover fill hole. it had moisture in it. after i changed the PCV valve the moisture was gone. dont for get all / most acids ( in your oil ) are water base.

No, I don't have a big HP engine but in some chevy forums I read that for example a 200 HP engine must have a different PCV valve than a 240 HP engine

Yup. Just walze' into the local Chineseo parts store, NAPA, O'Reallys, and tell 'em what year, make, model, and engine size and they should be able to look it right up.

Back in the day the PCV valve was replaced when the tuneup was done every 12,000 miles...I would use a oem dealer pcv Valve as to get the proper metering of air...I have found over the years alot of driveability issues with aftermarket PCV valves... Now most cars dont use the valve per say but rather a tube that pulls the vapors into the air intake causing the plenium to get all gunked up...So now some performance companies have gotten smart and for the performance car the speed shop people have come up with oil seperators for these cars/trucks....And you can drain the oil out of the seperator at oil change time...Bill

If you really need something different?
There is an adjustable one out on the market...

:)