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Thread: Pcv catch can

  1. #1
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    Default Pcv catch can

    I've done a top end rebuild on my LT1. I had multiple sources of oil contamination in this thing,(intake gaskets, rocker studs, etc.) I covered some of the rebuild in another thread. After the rebuild I eliminated the PCV system all together. I've got both valve covers tied together with Moroso breather caps(the type used for pan evac systems) through a 5/8" hose routed down to the air filter. It's basically venting similar to the setup on boat engines.
    Fast forward..... I do have a bit of blowby, it doesn't smoke out the breather tube but there is some crankcase pressure. It has pistons with the thin low tension ring package. It's a drag motor build. I think I may benefit the ring package by putting some vacuum on the crankcase. BUT, I don't want any oil contamination whatsoever in my intake track.
    My options are an electric vacuum pump that would produce vacuum on the crankcase at all times with a catch tank on the pump discharge. This is the expensive option.
    Or using the engine vacuum (9") and tie the PCV system back together using a catch can. This would be a less expensive option.
    But, my thinking was that under wide open throttle the engine vacuum would be 0" and allow the crankcase pressure to blow back into the intake tract through the breather line thus contaminating the intake and being right back at square one.
    What are you guys doing with drag style engines?
    Recommendations?
    Discussion?
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

  2. #2

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    Mightymouse draft can.

    What you described is how I have mine setup. When in vac the can pulls from one valve cover (other side has a breather) and when in boost the can seals and allows for whatever blow by to vent out the can.
    Correlation does not imply causation.

    Una salus victis nullam sperare salutem

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  4. #3
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    Default

    Hey Man , Thanks for the tip on the MightyMouse can. I looked at them and like the design. A bit different from the other stuff out there. Appreciate the feedback.
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

  5. #4
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    Default

    Why not a crank case evac kit since it's a drag motor?
    93 SRZ

    02 MY Z06, LG pro LT headers, catted X-pipe, Borla stingers, CC 224/228, CC918's, CAI, CCW's just your basic C5Z

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  7. #5
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    Default

    The reason I'm not using a pan-evac system is because the car is run on the street through a full exhaust system(true dual). I understand that the pan evac systems don't work well through full exhaust. I'm calling it a drag motor because thats the way it was built.(thin ring package pistons, loose clearances, long duration cam, etc.) I bought it with this engine and have been slowly improving it as time and funds allow. If I would have originally built the short block, it would have been done differently but I'm just working with what I have.
    I didn't think it had much blowby until I put my thumb over the breather hose for a short period of time and the oil dip stick popped up. Thats when I decided to work on putting some vacuum on the crankcase. I think the MightyMouse can will improve things.
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

  8. #6
    The Nitrous Outlet Junkie


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    Default

    Interesting.... i have lots of blow by on my car too ... i have been looking catch cans too and maybe a pair of those breathers that you mount in the headers... any one have experience with those?

    Sent from my SM-N950U using Tapatalk
    94 Formula; sleeper/budget build - total invested so far $5700,
    best pass on motor: 12.398 @109.4
    best pass on SPRAY:
    350, LT1, carb, LE grind cam, th400, 3800 stall, ford 8.8 w/ 4.10s


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  10. #7
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    Default

    Zooman, I don't have any experience with the evac type systems first hand. I have read about them on a few occasions and it seems like they were less effective on a car with full exhaust versus an open header drag car. The venturi tube that is welded into the header collector pipe is what creates the vacuum. When the flow is slowed down by a full exhaust system creating a restriction, the vacuum created by the venturi is lower. I suppose that it doesn't mean it won't work, its just a lower vacuum on the crankcase. From everything I've looked at, the evac type setup is a cost effective method though.
    '94 Z28 Bone stock,4l60e
    '97 SS SLP,T56,385 stroker,AFR210,XFI292,NO traction til top of 3rd gear.
    '57 Chevy 3100 p/u LT1/T56

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