? PVC vs. Carb adjustment

Been thinking about this. Say you run a PCV and either want to eliminate it or install a jet to restrict it a bit. How much of a change to the primary jetting is necessary to compensate for the richer mixture? (pcv is a calibrated vacuum leak) I'm assuming that this would only apply to the primary side of the carb, as the secondary should not be affected because the pcv would be closed due to the lack of vacuum, or not affected if the pcv is eliminated all together.

Google Wagner PCV and buy an adjustable PCV. It's much more simple. Isn't cheap. But better

I run one on the primary side on my 2" adapter and had to open the mixture screws about 1/4 turn to compensate for the "leak" w/no restriction and my pcv valve is from a 454 Chevy............

Using an adjustable PCV really doesn't answer my question.
As far as just adjusting the mixture screws only. I wonder if that would still lead to a lean condition at a certain rpm? I understand that the mixture screws have an effect on the f/a mixture up to around 3500 rpm in some cases. Wouldn't the mixture go lean above a certain rpm? I'm thinking that a real fix would be to go slightly bigger on the primary jets. Or go smaller on the IAB's. Thoughts?

I did go to .068 idle bleeds from .070 and it made it better........... The jets are active when on the boosters so if that was the range where it goes lean you could jet up or open the pvcr's up.........Whichever path achieves your goals or desired afr's although only part of tuning as they are just a "directional" tuning tool.........

My understanding is the PCV needs vacuum to open but when your at WOT there isn't much vacuum so you get no ventilation at WOT? When your racing isn't that when you need ventilation the most or oil starts to blow out of bad places (dipstick tube)? If that is correct a PCV valve does nothing to help when racing at WOT or does the Wagner adjustable PCV fix that issue?

I thought about running an EVAC breather to the header collector but these systems say not to run them on a car with mufflers. I'm building street/strip car.

I thought a PCV was a bad thing on a performance engine because you don't want oil getting sucked into the combustion chamber. How are you using them and what's the benefit?

That's why you run the pvc on one side and a good breather on the other after all, how long to you stay at WFO.............

I made a oil separator and my intake charge is nice n clean plus, get the Ford breather that has the pvc gromet in it to raise it farther away from liquid oil and stuff it w/open cell foam..........

I use both a PCV and EVAC. It's a closed system. I don't know how much pan vacuum it pulls. Some day I'll see if I can test it.

You have to put the EVAC after the muffle. With the mufflers I use it was easy to do. If your mufflers are back at the axle that would be a looooooooooong hose to get back there.

I run a crank case evac. system along with a pcv as my car is also mostly driven on the street. This way I have negative pressure in the crankcase at all times. I was thinking of installing a Holley jet in the pcv vacuum line to cut down on the amount of vacuum being drawn. In doing so, I was wondering if some adjustments might need to be made to the carb to compensate for the richer mixture?

Also, you can run an evac system on a car with mufflers as long as the mufflers are of a straight through design. (Dynomax, Magna flow, etc.) chambered mufflers will not work with an evac system.. I run Ultra Flows.

When my 434 was dynoed they unhooked the PCV valve before we started. After several pulls and all the tuning was done I asked about hooking it back up and making one more pull, it made 3 more peak hp.

PCV is a good thing for a street car so I'd think you might want to run one on your car. It is a simple way to suck the water vapor out of the crankcase and run it thru the engine.

The Wagner setup is the way to go for a hot street car since it is dual adjustable. I have one on my '65 Coronet and I have on on the Duster.

I run a PCV valve setup on my 63 as I prefer to run a PCV on a street car. As Andy stated it helps keep moisture and water buildup out of the crankcase. The PCV was actually put on engines for emissions and not for performance. But they help pull blowby fumes out of the crankcase and better then just breathers will. You need to make sure you use valve covers with good baffles so it don't pull any oil into the intake and as was said when at WOT the vacuum drops to about zero and the spring in the PCV valve close it. I run a breather to atmosphere on one valve cover and the PCV valve in the other so when I floor my car I still have one breather venting the crankcase. But when I drive on the street I hardly ever floor my car and the PCV is working good and it helps keep any pressure from building in the crankcase. During normal driving I feel the PCV will vent the crankcase better then running straight breathers and it don't effect performance any that you would notice. When I was at the track I unhooked my PCV valve and put a breather in both valve covers and then I hooked the PCV valve back up and ran it again. No difference at all in performance. In later years the manufactors went to the closed PCV system where the valve cover with the breather had a hose to the air cleaner and that let the PCV draw its air from through the air filter so it would draw cleaner air. And some were made so when the car was floored and vacuum drops to zero the air cleaner would actually cause a small vacuum in the breather hose run to the air cleaner and it could actually draw crankcase blowby through the breather hose while floored which was actually working backwards in the WOT mode. But that was only on the closed PCV system with the right type air cleaner. On the setup like mine where my breather goes to atmosphere when I floor it my PCV valve closes and it vents through just the one breather. Course when I race I can just block the PCV valve and put a breather in the other valve cover and run two breathers for just when racing since the PCV don't work at WOT. When I installed my PCV valve setup I just readjusted the carb idle mixture and have had no problems at all. Course if you run to large a cam and don't have enough vacuum then the PCV system wont work much at all. Mine still pulls enough vacuum that it works fine on my car. Ron

Did the state of Maryland put a one-paragraph limit on internet forum posts?

I think an oil separator like some mentioned previously would be a benefit.

Have a nice day

I run the Wagner adjustable valve on my Dakota. The accurate and stable vacuum signal creates a very predictable MAP signal for the JTEC. Mileage went up 3 mpg on the highway, but the throttle behavior is fantastic.

Far as I'm concerned it pays for itself and is well worth the price.

That's true until the vacuum drops to zero at WOT and then the spring will close the pcv valve as these pics say and show. And a backfire when stepping on the throttle will also cause the PCV valve to close. Ron

Since I'm wrong, please remove my quote from your post.

I just went from .040 to .042 ifr's in my 1200 Dommy and that was the ticket to get the mixture screws closer to the 1 1/2 zone instead of 2 out which was still a bit lean...........

I'm not as smart as you when it comes to carbs. I run a 4150 1050AN. My IFR's are .036". IAB's are .073" and the HSAB's are .033". Main jets are 85 and secondaries are 92. My mixture screws are out about 7/8's of a turn. Almost one full turn. No holes in throttle blades. I don't see how the IFR's would affect the mixture screws. They work the transfer slots.

Ifr's feed the idle circuit and it just happened and always does..........lol Oh, and I'm not that smart trust me.......

When you use IFR do you mean the idle fuel feed restrictors or the intermediate fuel feed restrictors?
I restrict, make both smaller on my street Dominator carbs, both fuel feed channels on the primary side

Idle feed restrictors and I've found lately it's easier to tune em a bit richer especially on motors w/cam n compression..........

I've asked the questions before about if/when the ifr's and t-slots become inactive and can it be seen on the dyno or not and never got a solid TESTED answer on the t-slots but did on the ifr's. When I went to the .042's to fatten the idle/transition, my car was rich all the way to 7000 r's and the normal .002 change leaner to the high bleeds made zero difference to the wot afr's. So I went back to the .040's and .067 idle bleeds instead of the .068's and the car responded to a leaner wot mixture and is pulling like a freight train to a nice 12.8 afr reading proving the ifr's carry all the way up to max rpm's and this was also confirmed by a well known dirt track builder who sees the exact same results.............Just when I think I'm figuring some things out, I find more and more scenarios w/these carb things and the learning never stops till WE stop wanting to try and learn all we can............