PVC valve ideas please...

Shakin66 · Jan 23, 2008

I ordered a billet aluminum pvc valve but was under the impression that the one valve in them was to allow pressure in the engine to escape and then route it to the intake. Its beautiful but its valve operates the opposite way, creating enough pressure to evenually blow the oil fill cap off the other side. So my thought is since I have not just vac. but also boost at the intake should I just "gut" the valve? I know with the 9# pulley on the S/C it blows pretty hard so I may be right back to creating pressure when I rev it up? Any ideas would be greatly great!

red65 · Jan 23, 2008

I'm working with this issue at the moment myself. The function of the Positive Crankcase Ventilation (PCV) valve is to allow flow from the crankcase to the intake, but not the other way around. In a supercharged application, that's particularly important since you don't want boost finding its way directly into the crankcase (which is what would happen if you gutted it, so don't do that).

There's some good tech on this on corral.net - look in the supercharger section - but the main gist is to make sure that the PCV valve seals, preventing boost from entering the crankcase that direction and, just as importantly, make sure that the crankcase ventilation on the other side is adequate - generally this means making sure that you've vented your valve covers well enough.

I've seen all kinds of approaches to this problem, since separating oil out from the vented crankcase is important too - that's why you'll see catch cans and separarators (like on an air compressor). Good luck.

Excellent tech here too - worth the read:

http://forums.stangnet.com/showthread.php?t=637524

Rusty67 · Jan 24, 2008

Do you need a PVC valve with a super charger ? On an NA motor you can just put breathers on both valve covers and you will be fine. If that wont working you can try a vacuum relief valve.

red65 · Jan 24, 2008

For a carbureted application, you can definitely just vent the crankcase, at the possible risk of oiling up the breathers. For an EFI application (like mine and, I think, shakin66's) you have to be a bit more careful to make sure that all of the air entering the engine is accounted for through the mass airflow sensor. There've been dozens of approaches to solving this problem with varying degress of effectiveness.

And, once and for all, it's a "PCV" valve, not a "PVC" valve. (P)ositive (C)rankcase (V)entilation.

PVC is used to make plastic drain pipes and lawn furniture.

Shakin66 · Jan 24, 2008

I am carb'd for now and I know I could just leave the breathers open but I just wanted to clean things up. Sorry PCV! I guess I have been buying to much pvc for my sprinkler system lately...On a positive note I finally drove it around town last night and I am now fired up to finish all the loose ends.

Rusty67 · Jan 24, 2008

red65 said:
For a carbureted application, you can definitely just vent the crankcase, at the possible risk of oiling up the breathers. For an EFI application (like mine and, I think, shakin66's) you have to be a bit more careful to make sure that all of the air entering the engine is accounted for through the mass airflow sensor. There've been dozens of approaches to solving this problem with varying degress of effectiveness.

And, once and for all, it's a "PCV" valve, not a "PVC" valve. (P)ositive (C)rankcase (V)entilation.

PVC is used to make plastic drain pipes and lawn furniture.

Typo

If you used a vacuum relief valve it would only be leting presure out into the engine bay and it wouldn't effect the amount of air comming into the motor because it is a 1 way valve.

Shakin66 · Jan 24, 2008

Well if thats the case then I should be able to use the old pcv valve that came out of the mid 70's 302 that was in there. I'll test that tonight and see what happens but I think its still going to blow the filler off.....Being that its carb'd I will end up just going back to the open type. Thanks for all the ideas which will certainly help whenever I do decide to F/I this thing.

Rusty67 · Jan 24, 2008

The reason I suguested the valve was that it is adjustable so you can tune it to your needs. The PCV valve is fixed to the rate of the spring that is inside it. Maybe your PCV valve is bad ? Have you tried puting a new one on ?

Shakin66 · Jan 25, 2008

Well I guess that goes back to the original problem of which way are these valves supposed to "flow" Mine old one flows out of the engine and the new one flows into the engine. So I am going to run them open and move on to the parking brake issue. I have Baer dics on the rear and bought their emergency brake cable kit but the t-56 crossmember covered the hole in the frame rail.....Its always something.
If anyone has a diagram or pics of the factory parking brake cable routing that would be a big help.

Rusty67 · Jan 25, 2008

You want the parking brake cables for the SN95 Mustangs or a 66 ? The Baer kit uses the SN95 calipers if I'm not mistaken.

Shakin66 · Jan 25, 2008

Well I have the cables but am now looking for a picture of the way its set up under the car. The t 56 crossmember is covering the pivot point I believe.

10secgoal · Jan 25, 2008

Go to the store and get a PCV from 93 Supra. Pop the 90 deg elbow off and you can put it line of a 3/8 line

KreagerM · Apr 7, 2009

Shakin66, i was hoping you could update me on what you decided to do to combat your crankcase pressure issue?

I'm in the same boat you were once in. Thanks for any advice you might have.

Matt

Shakin66 · Apr 7, 2009

I will have to check but I think that I gutted the inside of it. I will check that out tonight and try to get back to you. It was said that you can vent the breathers but you may have smoke under the hood if you go that route...

KreagerM · Apr 7, 2009

Thanks, I appreciate any help I can get.

Right now I have a pcv and a breather and I get some oil coming out of the breather.

I have a feeing it has to be something with my configuration or VC's (both openings are baffled). Because when this motor was in my buddies car he never had this problem and I had it right away even before the SC. I also had the same issue with my previous motor. I'm willing to try something new at this point. Oil catch can maybe?

68EFIvert · Apr 8, 2009

I could have asked the same question a week ago. I have been blowing pan gaskets and decided to do a little research on PCV's. I purchased a Motorcraft EV-111 and it took care of my problem. I haven't had a drip of oil since I replaced it. It was the best $5 I have spent. Give it a try or try a Supra PCV 10secondgoal mentioned. The nice thing about the EV-111 is it is a direct replacement. 30 seconds and I was done.

KreagerM · Apr 8, 2009

68EFIvert said:
I could have asked the same question a week ago. I have been blowing pan gaskets and decided to do a little research on PCV's. I purchased a Motorcraft EV-111 and it took care of my problem. I haven't had a drip of oil since I replaced it. It was the best $5 I have spent. Give it a try or try a Supra PCV 10secondgoal mentioned. The nice thing about the EV-111 is it is a direct replacement. 30 seconds and I was done.

Thanks, I'll have to give it a try.

KreagerM · Apr 13, 2009

68EFIvert said:
I could have asked the same question a week ago. I have been blowing pan gaskets and decided to do a little research on PCV's. I purchased a Motorcraft EV-111 and it took care of my problem. I haven't had a drip of oil since I replaced it. It was the best $5 I have spent. Give it a try or try a Supra PCV 10secondgoal mentioned. The nice thing about the EV-111 is it is a direct replacement. 30 seconds and I was done.

I noticed there is a Motorcraft MIEV111 and an EV111. Anyone know the difference? I also read somewhere about someone using an EV153 (reverse flow PCV) anythoughts???

68EFIvert · Apr 13, 2009

I also came up with the same results on my research about the EV153 but went with the 111 because it seemed to be the more popular choice. I can't answer your first question, sorry.

D.Hearne · Apr 13, 2009

Shakin66 said:
I ordered a billet aluminum pvc valve but was under the impression that the one valve in them was to allow pressure in the engine to escape and then route it to the intake. Its beautiful but its valve operates the opposite way, creating enough pressure to evenually blow the oil fill cap off the other side. So my thought is since I have not just vac. but also boost at the intake should I just "gut" the valve? I know with the 9# pulley on the S/C it blows pretty hard so I may be right back to creating pressure when I rev it up? Any ideas would be greatly great!

From your description, it sounds to me like you're running the PCV valve with a closed, non-vented oil filler cap. If that's the case, that's where you've gone wrong. You have to use a vented filler cap to allow fresh air into the crankcase and allow the PCV valve to function. Without a fresh air supply the PCV valve diesn't function and that's how the crankcase pressure's building and blowing the filler cap off. You're just lucky it didn't blow the front and rear main seals too at the same time.

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