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Technical Buddy of mine has a smok'in 383 Shivel-lay...

Discussion in 'Traditional Hot Rods' started by 6sally6, Dec 25, 2021.

  1. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,894


    Big cam... gear drive....10:1 CR...Eddy heads. He has a problem with oil seeping out of valve covers around the hold down bolt HOLES. We put O-rings under the bolts and that helped but after hard running he get small amount dripping out of holes AND smoke coming from VC breather.
    NO smoke from exhaust so I was think'in (usually a bad thing!) maybe the PCV is not working enough with this modified engine to keep the oil vapors sucked out of the engine.
    Pretty sure it has a standard pressure oil pump but.....VC's may be over flowing with oil after some high RPM runs. Our next step IF new VC gaskets don't work is to go with NO gaskets and use thick beads of RTV under the VC.

    Question is about he PCV..........Anybody recommend a GM high performance PCV to use instead of the standard 283-327-302-305-350 PCV? (He's too poor for one of the adjustable PCV units so don't even go there.)
    Does the Corvette HP engines use a better PVC??!
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 19,925


    What PCV valve is in there now?

    How is fresh air drawn in?

    BigDogSS, Deuces, Tim and 1 other person like this.
  3. 427 sleeper
    Joined: Mar 8, 2017
    Posts: 1,708

    427 sleeper

    If he's running a big cam, something on the order of a 327/365 PCV system might be optimal, a fresh air intake at the carb and a restricted orifice in the valve cover or oil fill tube hooked to a vacuum source. Like Gimpy say's... Picture's? ;)
    Last edited: Dec 25, 2021
    Deuces and gimpyshotrods like this.
  4. PotvinV8
    Joined: Mar 30, 2009
    Posts: 209


    That setup doesn't lead me to believe there's excessive crankcase pressure being built up. I have a 383 with similar compression that's seeing 6-8lbs boost and has an oil filler/breather in the intake and two foam inserts acting as breathers in the valve covers. No problem with any oil blow by.

    I don't like PCV valves as I don't like putting all that crap air back into the intake stream. Seems counterproductive to me, but I see the point in using one to "draw" the vapors out. But I would think a decent set of breathers would allow the engine to vent whatever pressure it was building up without the need to try to suck it out with a PCV.

    A catch can equipped with a breather and plumbed to both valve covers has worked well for me in the past to keep the crankcase ventilated and eliminate the oily blow by that can sometimes happen.

    Make sure the bottom of the valve covers are not contacting the heads or intake before the gasket is being crushed and use a good silicone rubber gasket. Shouldn't require o-rings or RTV.
    Deuces, rod1 and loudbang like this.

  5. el Scotto
    Joined: Mar 3, 2004
    Posts: 4,496

    el Scotto
    from Tracy, CA

    That’s not an oil leak, that’s the horsepower sweating!

    Seriously though… what kind of valve covers? Over tightened and damaged gaskets? If steel do they have the little spreader chinguses on them?
    MAD MIKE, Deuces and Tutashen like this.
  6. DDDenny
    Joined: Feb 6, 2015
    Posts: 16,059

    from oregon

    We don't need no stinking PCV!

  7. TA DAD
    Joined: Mar 2, 2014
    Posts: 624

    TA DAD
    from NC

    6sally6, if running it hard means WOT . The motor has no vacuum or very little at that point so the PCV will not be working. That is why you run some other type of vent system.
  8. When the Valve covers are off, check the oil return holes to make sure they are not partially obstructed by the head gasket. Oil may not be draining fast enough at high RPM.
  9. sunbeam
    Joined: Oct 22, 2010
    Posts: 5,607


    corvair valve cover clips
    Deuces likes this.
  10. jaw22w
    Joined: Mar 2, 2013
    Posts: 1,464

    from Indiana

    Are you talking about perimeter bolt valve covers or the newer center bolt covers?
    Deuces likes this.
  11. Tickety Boo
    Joined: Feb 2, 2015
    Posts: 1,479

    Tickety Boo
    from Wisconsin

    I like running a header crankcase evacuation system like Mr Gasket #6002, really helps the gaskets and seals live and might save some H.P. by helping the rings seal, works real well on a drag car, can feel the suction off the hose at idle.;)
    I also get a little misting out of the breathers when winding up the street car, so been thinking about installing this kit by putting the header fittings after the mufflers, near the end of the tail pipes where there is no back pressure, hoses would be long but thinking it will work.
  12. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,894


    Deuces likes this.
  13. mikhett
    Joined: Jan 22, 2005
    Posts: 1,413

    from jackson nj

  14. NoelC
    Joined: Mar 21, 2018
    Posts: 95


    It could just be me, but what we have here is a failure to communicate.

    Pretty typical of these kind of questions when they are asked. Not enough information given, and a few questions left unanswered.
    I have to say however, while we could get to the bottom of this, it's solid entertainment reading the replies.

    But if I had to's an older sbc, recently rebuilt, the PCV valve is connected off the back of the block, the under the manifold baffle is missing, drain back casting hole flashing weren't opened up as block prep, and there is no windage screen in the pan. That's my guess.
    Tickety Boo, Deuces and Tutashen like this.
  15. deathrowdave
    Joined: May 27, 2014
    Posts: 2,830

    from NKy

    Venting the crankcase is flow through process and any type of venting can only vent as much as system will pass . Meaning if more pressure is induced than the system will flow out , you have pressure in the crankcase . My old OT Power Wagon is diesel powered , no vacuum to evacuate the crankcase , with 25 psi of boost at load , it has a 1 in slumber tube to vent pressure and it drips upon shut down . My old Harley’s are the same , they are dry sump oil system , which is a bit different over a normal car engine. They fire really strange and yes they have blow by pressure build up as a normal part of the process , leaks . Nothing is 100 % seal , the engine could be fresh or loose and rings not seating causing pressure issues . A hot compression test would be in order for me next . I know 6 , you don’t want to hear this , I would not either . There are lots of issues that could cause this , problem , just need more info . Maybe restrictors need to be installed in the oil galleys to limit oil flow to the top end . Just need more info and help to find the answer is here with one of us .
    BradinNC likes this.
  16. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


  17. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


    Yeps there's flash most times around the drains should be ground out when the heads are off an the valve train is fed back to front so oil pools at the back of the heads but leaking at the bolt holes geesh got me there
  18. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


    o if the valve seals weren't put in right maybe the exhaust valves are smoking up the covers would expect to see at least some exhaust smoke though but who knows at wot at the track might not see it
  19. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 702

    from 94577

    ^Asking the real questions.
    Always check, without gaskets or goo, your VC to head fitment.
    Even with new heads(cast or machined) and VCs(stamped or cast) they may not be square to each other. Spend time on making sure the tin fits the head/block without gasket, goo, or forced flat with a fastener first. VC should sit flush on the head. Fix the pooching in the flanges
    Smoke/mist can be normal depending on hot/hard the engine is being run. You are always going to get a bit of oil vapor. If it is chugging smoke from the breather, verify that it is not being inundated with oil and has a proper filter to keep mist from getting past. Some breathers are not filtered and are merely liquid separators.
    Placement and height is critical.
    Too low, too small(surface area), and at the extreme ends of the VCs will cause unwanted flooding and excess misting.
    Circle track guys use a crossover at the front with two breathers. Crossover allows for pressure balance between the two banks, the added height prevents flooding. It's not the most elegant and may not be period correct, but it is simple/cheap/works.

    If it is just a breather setup on both covers and no fresh air for the crankcase ventilation, if the oil is filling the VCs then blowby can pressurize the crankcase. Which in turn does not allow for quick drainage of the heads. Exacerbating the problem.
    In a street engine with a PCV and PCV valve system one side acts as the fresh air intake and the other side is a controlled vacuum source to keep air circulating.
    With just two breathers, there isn't any way to keep air moving. Just relying on the pressure differential from crankcase up to the heads to allow excess buildup to vent out. This works fine under normal conditions but under higher rpms the higher pressures in the crank case and oil flooding will just work against each other.
    OEMs on newer cars spend quite a bit of engineering on the PCV system to get the oil into the crankcase. Fords mod V8 uses dedicated drain ports from head to block that bypass the crank to prevent windage and expedite oil drainage.
    Not to mention the baffling used throughout...

    Your friend is using baffles... right?
    Not really a bad thing, oil keeps the valvetrain alive.
    Is there enough capacity in the system to allow oil drain and ventilation.
    Every step in modifying the engine will need an equal response in maintaining an equilibrium with engine subsystems. A breather system that works fine on a stock 327 is probably going to have some issues on a high rpm 383. It's simply a question of capacity.
    That's not going to fix the problem. If it's leaking now, it will still leak with some of the compliance(gaskets) of the mating surfaces removed.
    Factory PCV systems are for factory type engines.
    A valve is not going to be the end all fix, it's a system. Need to address the short comings.

    We need pictures of the current system to better help you.
  20. Subscribed. My 10,000 mile 355 may need some more crankcase ventilation. The stamped valve covers leaked, they sucked in the gaskets at the ends, and I had good gaskets on it. It does leak from a few places, cast valve covers and better gaskets were put on, so that leak is fixed.
    Deuces likes this.
  21. jaracer
    Joined: Oct 4, 2008
    Posts: 1,476


    On the race car I ran Corvette cast aluminum valve covers and never had any seepage of any kind. I also had the covers off about once a week to check valve lash. I used cork gaskets glued to the valve covers with trim adhesive. The gaskets lasted a long, long time.

    Ran with a lot of guys who had valve cover leaks all the time with the stamped and/or aftermarket valve covers.
  22. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


    Most chrome valve covers don't match either the cheap chinese gaskets or the rim on the head an that might not be cast very well either so there are three things don't match , safety people call that an accident waiting to happen lol , chrome ones aside from holding heat are mostly cheap bend easy so hammer away , i heat the rubber gaskets in oven on low while waiting for glue to get sticky on the covers so they stretch to fit the covers that don't fit , best thing is to use stock covers an paint anyway you want or cast covers an when heads are off put straight edge on them an fix them so they seal , done right you can do your valves for yrs without changing gaskets , the leaking around the holes is something going on so stupid you will hit yourself when you figure it out an i don't think it's some making 3000 horse sucking the oil out of the motor thing , my daily driver is a 283 stroked to 354 ish 11.5 cp with stock pvc an breather on the other cover an if it doesnt have lots of crankcase pressure no engine does um just a tip :)
  23. My OG covers were from Dart and didn't lock the gasket in like some cast covers. I have been tying the gaskets to the covers for years with heavy sewing thread, also glue the gaskets to the covers with gorilla snot. Now I'm using either Mr. Gasket or Moroso cork gaskets. I have plans to pop-rivet some stops on the Dart covers so the gasket ends don't get sucked in.
  24. Summit Racing sells a really good store branded rubber rocker cover gasket. I run a high volumn pump on my 355 (I set it up loose) and after a 7K pull it would leak. The rubber gaskets cure it.

    I cannot help with your blow by, I may ask a ton of questions concerning that but most of them ate not likely going to be answered here. If the engine is not pulling enough vaccum for the PCV to work, you may need to go to a vacuum pump to evacuate he crank case. I do not normally run into that on a naturely aspirated motor but it is something we have had to do on our turbo charged motors. A cheap solution and the most viable for a street motor is to use a smog pump off of a Ford. They are made to last the life of the motor on a street driven vehicle. Most of the race model vac pumps do not have much longevity.
    raven likes this.
  25. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


    Came to me this morning , what's the oil pan like , if it's really winding out an there are no baffles or crank scrapers the oil could be turning to foam , just a thought seeing as how nothing is known about the build
  26. bchctybob
    Joined: Sep 18, 2011
    Posts: 3,620


    I had a similar problem when I ditched the Pep Boys valve covers on my coupe and installed the older style Edelbrocks. A significant amount of oil was coming out of the valve cover hold down bolts and getting on the hot headers. Lotta smoke. I bought some good Fel-Pro gaskets and some studs, I put a fillet of silicone around each stud before installing the gaskets and a little more on the valve cover side of the gasket. No more leaks.
    My heads are the Blueprint aluminum heads that came on the 430 hp 383 crate engine that was in the car when I bought it. They have some very strange milled slots running through the hold down bolt boss that I don't understand and they may have contributed to the leaking.
    IMG_E2881 (2).JPG
  27. Tutashen
    Joined: Aug 8, 2015
    Posts: 86


    Nice heads i'm jealous lol , almost looks like somebody cut those slots after they got the heads hey
  28. blowby
    Joined: Dec 27, 2012
    Posts: 8,307

    from Nicasio Ca

    Never heard 'Shivel-Lay' before, anyone else? What's a Shivel? If you mean to be derogatory, try Shrivel-Lay. :)

  29. DDDenny
    Joined: Feb 6, 2015
    Posts: 16,059

    from oregon

    Anything but "Chebby"........Cripes!
  30. Jacksmith
    Joined: Sep 24, 2009
    Posts: 865


    I'm missing what block's in there... If it's older with the rear breather, this is what stopped mine from leaking, if that helps.
    IMG_0237.JPG IMG_0238.JPG IMG_0240.JPG

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