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Thread: PCV Question

  1. #1

    Default PCV Question

    I've been doing as much reading as I can, since I'm still somewhat new to EFI. I was reading up on IAC tuning a came across a thread that also discussed PCV. On the engine I just put in my truck with a Terminator X system, I used the Sniper valve covers (PART# 890013B) with no vents due to the Ford truck intake. The one cover has the oil fill and a small vent tub on that. My thought was to connect this to a port on the intake. There is no valve in there just a screen if you will and no vents on the other valve cover. The more I read I'm thinking this is not going to work properly. Will this work as described or am I going to have issues? If I need to add a PCV valve what would be the best location and way to do it with these valve covers?

  2. #2
    Join Date
    Dec 2009
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    Yes, you still need a PCV valve. Aftermarket EFI doesn't change any of that.
    If your new valve covers don't have a provision for a PCV valve,
    drill the appropriate hole and install a PCV valve rubber grommet.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  3. #3

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    OK, so to do it right the tube on the oil fill would go to the air cleaner in front of the throttle body and I need to put a PCV in the other valve cover and connect to the intake behind the throttle body?

  4. #4
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    A picture of the top of your engine would be helpful. Open element air cleaner, valve cover port options, etc.
    http://www.460ford.com/forum/42-gene...cv-system.html (Closed PCV System)
    https://forums.holley.com/showthread...1540#post51540 (Related Forum Post)
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  5. #5
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    I used to run a conventional PCV system. This type of system does nothing to create vacuum in the crankcase. I have a MAP sensor on the crankcase and I was getting positive pressure in the crankcase with a conventional PCV system. And I was always getting oil leaks. No mater how many times I sealed it up, it would always leak oil. I had to keep mats under the car to sock up all the oil.

    So, this is what I did to fix the problem. I got a fixed orifice PCV valve. I then put a one way check valve in the line between the PCV and the manifold so it could only pull vacuum in the direction of the manifold. I then put a restriction in the vent line going from the breather in the other valve cover to the TB. I then played with the sizes of the PVC valve and the restriction in the vent line until I got about 7" of vacuum in the crankcase at idle. Then I Teed off the vent line and connected an electric smog pump. And then I put an one way check valve before the pump. As I am driving around the crankcase gets its vacuum from manifold vacuum and when the vacuum in the crankcase drops below 3.5" of vacuum or I go to WOT the ECU turns the smog pump on and it keeps the crankcase vacuum at around 5" of vacuum. Since doing this all my oil leaks have stopped and the mats are now gone. And as a bonus the vacuum in the crankcase helps ring seal.
    https://www.amazon.ca/Return-Check-V...gateway&sr=8-5
    https://www.summitracing.com/int/par...iew/?rrec=true
    Last edited by 81 TransAm; 12-31-2019 at 08:54 AM.

  6. #6

    Default

    I pulled the valve cover and put a PCV valve in.

  7. #7
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    Quote Originally Posted by 81 TransAm View Post
    I used to run a conventional PCV system. This type of system does nothing to create vacuum in the crankcase. I have a MAP sensor on the crankcase and I was getting positive pressure in the crankcase with a conventional PCV system. And I was always getting oil leaks. No mater how many times I sealed it up, it would always leak oil. I had to keep mats under the car to sock up all the oil.

    So, this is what I did to fix the problem. I got a fixed orifice PCV valve. I then put a one way check valve in the line between the PCV and the manifold so it could only pull vacuum in the direction of the manifold. I then put a restriction in the vent line going from the breather in the other valve cover to the TB. I then played with the sizes of the PVC valve and the restriction in the vent line until I got about 7" of vacuum in the crankcase at idle. Then I Teed off the vent line and connected an electric smog pump. And then I put an one way check valve before the pump. As I am driving around the crankcase gets its vacuum from manifold vacuum and when the vacuum in the crankcase drops below 3.5" of vacuum or I go to WOT the ECU turns the smog pump on and it keeps the crankcase vacuum at around 5" of vacuum. Since doing this all my oil leaks have stopped and the mats are now gone. And as a bonus the vacuum in the crankcase helps ring seal.
    https://www.amazon.ca/Return-Check-V...gateway&sr=8-5
    https://www.summitracing.com/int/par...iew/?rrec=true
    A conventional PCV system does not create a vacuum in the crankcase. Was never designed to. Impossible to create a vacuum since the other side of a typical V configuration engine is plumbed with a large hose to a filtered air source. Any engine that has oil leaks has insufficient air flow for blowby, either by a push-in breather filter, or hose too small to the base of a carb air filter. I run a AN16 hose on the breather side, AN6 on the PCV valve side. PCV valve is sized for the engine. Reliable system for a street car. Yes, your vacuum system has merit, but if it ever fails, you will have instant oil leaks, including pushing seals out of the engine. Gary
    Regards, Gary

  8. #8
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    Quote Originally Posted by Gaz64 View Post
    A conventional PCV system does not create a vacuum in the crankcase. Was never designed to.
    Exactly, it's only designed to positively vent the crankcase, hence the name PCV - Positive Crankcase Ventilation.
    May God's grace bless you in the Lord Jesus Christ.
    '92 Ford Mustang GT: 385" SBF, Dart SHP 8.2 block, TFS TW 11R 205 heads, 11.8:1 comp, TFS R-Series intake, Dominator MPFI & DIS, 36-1 crank trigger/1x cam sync, 200A 3G alternator, Optima Red battery, A/C, 100HP progressive dry direct-port NOS, Spal dual 12" fans/3-core Frostbite aluminum radiator, Pypes dual 2.5" exhaust/off-road X-pipe/shorty headers, S&W subframe connectors, LenTech Strip Terminator wide-ratio AOD/3000 RPM converter, FPP aluminum driveshaft, FPP 3.31 gears, Cobra Trac-Lok differential, Moser 31 spline axles, '04 Cobra 4-disc brakes, '93 Cobra booster & M/C, 5-lug Bullitt wheels & 245/45R17 MT tires.

  9. #9
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    Quote Originally Posted by Gaz64 View Post
    A conventional PCV system does not create a vacuum in the crankcase. Was never designed to. Impossible to create a vacuum since the other side of a typical V configuration engine is plumbed with a large hose to a filtered air source. Any engine that has oil leaks has insufficient air flow for blowby, either by a push-in breather filter, or hose too small to the base of a carb air filter. I run a AN16 hose on the breather side, AN6 on the PCV valve side. PCV valve is sized for the engine. Reliable system for a street car. Yes, your vacuum system has merit, but if it ever fails, you will have instant oil leaks, including pushing seals out of the engine. Gary
    I agree, but my problem was I was getting a slight positive pressure in the crankcase at heavy loads were a PCV system will have zero affect on it because there is zero vacuum to vent the crankcase. My initial plan was to only use the vacuum pump at WOT, but then I decided to put the crankcase under vacuum at all times. So this is where I ended up. The only thing that can fail in my system is the electric vacuum pump, and I have a MAP on the crankcase that will turn the pump on and also activate a LED light when vacuum in the crankcase is low alerting me to a problem.

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