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Hot Rods sbc -pcv location.

Discussion in 'The Hokey Ass Message Board' started by 51Hg, Nov 28, 2009.

  1. 51Hg
    Joined: Aug 12, 2004
    Posts: 212

    51Hg
    Member

    Has anyone added a shroud and put a pcv in a block off plate for the fuel pump on a small block chevy? If you did how did it work? Any pros or cons? Show some pics if it works?
     
  2. Spity
    Joined: Dec 20, 2008
    Posts: 438

    Spity
    Member

    I think you would want the PCV as high as possible, typically they were on vavle cover, or on the oil fill tube. You would still need a breather, where were you thinking of putting that at?
     
  3. Hyway Hauler
    Joined: Aug 31, 2009
    Posts: 670

    Hyway Hauler
    Member

    That sounds like a dumb place to put a pcv, it wouldn't even work right...it would probably fill itself with oil...
     
  4. 51Hg
    Joined: Aug 12, 2004
    Posts: 212

    51Hg
    Member

    I got some finned valve covers with no holes, and an intake with no oil fill tube. I was wanting to use the valve covers. wondering if i can make it work? was going to add breathers on the side of the vale covers but don't know what to do with the pcv?
     

  5. How were you planning on putting oil in it ?
     
  6. 51Hg
    Joined: Aug 12, 2004
    Posts: 212

    51Hg
    Member

    through the mooneyes style added side breathers?
     
  7. If you're using breathers you don't need a pcv valve.
     
  8. 51Hg
    Joined: Aug 12, 2004
    Posts: 212

    51Hg
    Member

    so finned no hole valve covers with added mooneyes style breathers equals no pcv? Just block it off at the carb?
     
  9. If your engine is fairly fresh and dosn't have alot of blowby yes. It will vent through the breathers. Funny story that happened many years ago. We had an old dirt track late model racecar and blew up the "good" engine one Friday night. Had a race on Saturday at another track that we really needed to make to keep our place in the points. Stayed up all night Friday night and pulled a tired 350 out of a Chevy station wagon and stuck it in the car and made it to the track just in time on Saturday. Every time we went into the turns the car would smoke like hell out the exhaust but would clear up going down the straights. Ended up finishing third in the feature and keeping our spot in the points and figured out later that the PCV (in the right side valve cover) was sucking oil into the intake when the oil puddled in the valve cover and burning off going down the straights. This is why you'll only see breathers on the left side on a circle track car and no PCV valve.
     
    Last edited: Nov 28, 2009
  10. Spity
    Joined: Dec 20, 2008
    Posts: 438

    Spity
    Member

    I disagree.
    Someone can probably explain this alot better than me, but you need the system to circulate, and having just breathers does not effectively clear out the motor. It would "work" but it wouldnt work as good as it could.
     
  11. 51Hg
    Joined: Aug 12, 2004
    Posts: 212

    51Hg
    Member

    interesting..
     
    Last edited: Nov 28, 2009
  12. scottybaccus
    Joined: Mar 13, 2006
    Posts: 4,109

    scottybaccus
    Member

    I suggest you read this article: http://en.wikipedia.org/wiki/Pcv_valve

    It was the one emmisions control that really made a difference. It also helps engines live happy lives by lowering pressure in the crankcase just enough to aid ring seal.

    Breathers and road draft tubes are a big waste. No vent at all is just plain bad.

    I have the same situation. If you don't want to see the pcv valve sticking out of the cover, you can use an add-on breather as a cover to camoflage things, or you can pt it some place discrete. Some have put a hole in the rear of the lifter valley on the block. I plan to put it in the center of the valley pan on an air-gap intake. You can use a rubber grommet to mount it and keep it easy, but it will look more like a vac hose or oil plumbing if you use a screw in valve. Go by the parts store and grab one of every valve that looks like you could use it, then look each one up in the application book to see where it is used on a similar engine. Look for a V8 application of similar displacement so the valve will agree with your vacumme characteristics.
     
  13. cvstl
    Joined: Apr 15, 2009
    Posts: 1,469

    cvstl
    Member
    from StL MO
    1. H.A.M.B. Chapel

  14. dannyego
    Joined: Mar 12, 2008
    Posts: 1,387

    dannyego
    Member

    Put the mooneyes breathers on the side like you were talking about. Then bite the bullet and drill a whole in your valve cover for the pvc. THats what I did after going through the same thing you did. Its functional and not real noticeable. sorry I didnt have a better pick. The pcv is on the leftside towards the back of the valve cover
     

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  15. studebaker46
    Joined: Nov 14, 2007
    Posts: 682

    studebaker46
    Member

    they make a plate that goes under carb to use a screw in type any engine shop should be able to tell you how and where tom
     
  16. oj
    Joined: Jul 27, 2008
    Posts: 6,263

    oj
    Member

    Yes, the pcv can go in the fuel pump block-off plate, on the race cars thats where we connect the vacuum pump and does the same thing. You would still have to let air into the engine somewhere to complete the circuit, the pcv is a breathing device, perhaps drilling a hole into the lifter galley (ie, thru the exposed floor of the intake) and either putting a smallish K&N filter on it or running it into the base of the air cleaner. It'll be tight drilling if you have a stock-type dual plane intake.
     
  17. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus

    I hate it when guys tell a newcomer to do a search...but do a search!:D:D

    This has to be one of the most popular and misunderstood questions. There is a wealth of information here on the HAMB. A lot of misinformation too. Like all you need is a breather.

    No, a PCV valve is not a pollution control. There are probably 5 or 6 long threads with lots of solutions to the finned VC/PCV problem. Some of them explain what it's main purpose is and how it works. Those who think all you need is a breather should do a search also. Your engine will thank you for it.

    There is too much information that has been typed out over the years to retype it every time the question comes up.
     
  18. MarkzRodz
    Joined: Sep 12, 2009
    Posts: 533

    MarkzRodz
    BANNED

    Your also to run a pvc for the vacuum it creates in the crankcase.
    It helps the rings stay seated and also pulls loosened carbon particles past the pistons. If you ran a pvc with the open breathers,,well,, it defeats the purpose and causes a big vaccuum leak. You'll lose (reduce) the carburetor's air metering signals too. The pvc also burns crankcase fumes that can leak out (environment) and smell up the interior. The pvc burns those fumes by directing them back into the combustion cycle process. The correctly placed opperating pvc reduces gasket (oil) leaks at the valve covers, timing chain and oil pan. It makes sense to run only a pvc ,,the old valve cover breathers and road drafts were old technology and were for the track until they got smart and started running Vaccuum Pumps. I understand persuing the old look though.
     
  19. dirty old man
    Joined: Feb 2, 2008
    Posts: 8,912

    dirty old man
    ALLIANCE MEMBER

    X2
    Dave
     
  20. man-a-fre
    Joined: Apr 13, 2005
    Posts: 1,311

    man-a-fre
    Member

  21. Here's what I did on my "too new 350" with old style non-vented valvecovers.
    I used an older Edelbrock manifold that had an oil fill tube in the front with a
    60's vented/filtered cap. You can't see the filler neck because I shortened
    it and it's behind the air cleaner snout but it's just stock Chevy.

    [​IMG]

    I drilled through to the lifter galley on the intake manifold's inboard coil
    mounting boss, behind the carb. Then tapped it for pipe thread. Using this
    boss will raise the inlet up away from the floor of the manifold a little.

    Installed a 90* fitting in the new hole. (I had to trim 3/8" off the top of
    the manifold mounting boss as the 90* elbow hit the base of the
    distributor.

    [​IMG]

    On the underside of the intake where the new hole is, I made a sheet
    metal pan to cover the hole so oil wouldn't get sucked up. The metal pan
    was rivited to the bottom of the intake and fit fairly close. It was about 3"
    square and trimmed to fit the contours.

    Used a "Corvette style" screw-in PCV valve at the base of the carb. Make
    sure your PCV flows the correct direction and make sure it works in the
    horizontal position. I already had the PCV in my spare plumbing parts so I
    don't know exactly what it's from, probably a 1960's Chevelle.

    I had an old 50's remote oil filter so I plumbed it between the new hole in
    the intake and the PCV with some copper tubing. I figured if any oil got
    sucked up, the canister would catch it.

    [​IMG]

    Works great, doesn't blow oil out the vented filler neck and doesn't suck oil
    into the PCV. Would probably work without the canister. I've opened it and
    there's been no oil inside.
     
  22. MarkzRodz
    Joined: Sep 12, 2009
    Posts: 533

    MarkzRodz
    BANNED

    You need to read more about engines. I've been building engines for 30 years. Also read drag race theory on engines(vacuum pumps/ring sealing). What exactly is bullshit? I'd expect some disgreement but not such panty waiving.
     
  23. tommy
    Joined: Mar 3, 2001
    Posts: 14,757

    tommy
    Member Emeritus


    The part about pulling a vacuum on a street driven car with a standard street PCV system. It's open to the atmosphere to get air flow through the crankcase so there can be no vacuum in the crankcase.
     
  24. Mr48chev
    Joined: Dec 28, 2007
    Posts: 29,813

    Mr48chev
    ALLIANCE MEMBER

    + 1, that's the same reason you often see engines with two breathers and no pcv with oil all around the breathers.

    It will work ok on a race engine but it really isn't the best on a street engine.

    Even road draft tubes are down in the airflow when the vehicle is moving to "draw" the fumes and pressure out of the engine.

    The pcv system draws those fumes through the intake instead of letting them fart out into the engine compartment.


    One suggestion on another board for a guy who didn't want to drill holes in top of his valve cover was to put the pcv valve at the back end of one valve cover. It would be pretty well out of sight but still work.

    If you don't have the mechanical fuel pump and want to vent the engine through that spot why not weld a tube/pipe to a fuel pump mount plate to raise the pcv valve up several inches? With a standard 1-1/8 rubber pvc plug to hold the pcv valve it might also work as an alternative oil fill.

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  25. Astrochimp
    Joined: Sep 15, 2009
    Posts: 191

    Astrochimp
    Member
    from NE Mo.

  26. MarkzRodz
    Joined: Sep 12, 2009
    Posts: 533

    MarkzRodz
    BANNED

    http://www.dragstuff.com/techarticles/vacuum-pumps.html.
    No problem,,I don't appreciate you saying bullshit.
    Hey! We're even. I'm old and have built hundreds of engines and tuned up hundreds more. The pvc works off the manifold vacuum. If the pvc is hooked up correctly then there will be a constant vacuum in the crankcase. If you pull the pvc off a healthy running small block it changes the idle several hundred rpm.It becomes a vacuum leak. If you have a breather or opening in the valve cover that will be a vacuum leak. Vacuum leaks cause carburetor problems, one is running lean and lower intake vacuum which kills the vacuum signal in the carburetor.
    I'll tell you another thing,,take off the pvc and plug it and any other breather and run the sealed engine,,you'll blow gaskets and/or have bad oil leaks from the pressure created in the crankcase (from the build up of pressure from the blowby off the rings).This article explains what I was trying to say.I have always run the "closed pvc system" on all my engines,,that Sir 440 aint bullshit .http://www.the-crankshaft.info/2009/09/crankcase-emission-control.html
     
    Last edited: Nov 29, 2009
  27. Dan57
    Joined: Nov 27, 2009
    Posts: 89

    Dan57
    Member

    i don't mean to be a smartass but it's pcv not "pvc". Positive crankcase ventilation.
     
  28. But you could run a piece of PVC in a PCV system :D
     
  29. bob308
    Joined: Nov 27, 2009
    Posts: 220

    bob308
    Member

    for a pcv system to work right the filtered air or air in has to be as far from the valve as you can get it. like in the 60's vette motors the air in is in the back of the block and the draw side with the valve is on the oil fill.

    on the dirt cars we used the pcv in one valve cover and the air in on the other. it helped to keep the motor cleaner.
     
  30. Special Ed
    Joined: Nov 1, 2007
    Posts: 6,934

    Special Ed
    Member

    Exactly...:)
     

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