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  1. #1
    Join Date
    Apr 2010
    Posts
    628

    Default Oil blowing from valve covers

    I was just wondering if anybody has any ideas, ive got a mild all steel wet sump motor. All star fabricated valve covers. We turn about 6500 and itíll blow oil out of my breathers. We do all our machine work and I know the cylinders are straight and good finish, this is the 2nd set of rings Iíve put in thinking maybe the first set didnít get seated right but hasnít made any difference. So now Iím leaning towards the top of the head is not draining back fast enough and itís causing it. I was just wondering if anybody else has ran across this and found a solution. Thanks

  2. #2
    Join Date
    May 2007
    Location
    Kansas
    Posts
    1,641

    Default

    Swap valve covers with a set you know didn't blow oil. If those covers have too small an air way or baffled too much, it makes the air come out at high velocity and carries oil vapor with it. The oil then puddles in the breather and drips out. Also put breather at the top of tube so any oil that does make it there can run back down tube, I see many people but the breather too low so the tube sticks up in the breather making it catch oil and has to drain out of the breather.

    Also check if no baffles or just a large hole that it isn't directly over a rocker push rod hole or something that is squirting oil up the hole/tube
    Last edited by billetbirdcage; 03-14-2021 at 08:08 PM.

  3. #3
    Join Date
    Apr 2010
    Posts
    628

    Default

    Quote Originally Posted by billetbirdcage View Post
    Swap valve covers with a set you know didn't blow oil. If those covers have too small an air way or baffled too much, it makes the air come out at high velocity and carries oil vapor with it. The oil then puddles in the breather and drips out. Also put breather at the top of tube so any oil that does make it there can run back down tube, I see many people but the breather too low so the tube sticks up in the breather making it catch oil and has to drain out of the breather.

    Also check if no baffles or just a large hole that it isn't directly over a rocker push rod hole or something that is squirting oil up the hole/tube
    thanks billet ill try that. after hot laps it was completely dry and after the heat race it had some drips. i figured its a fine line between having the tubes too restricted vs not enough

  4. #4
    Join Date
    Sep 2009
    Posts
    723

    Default

    I have run both cover without breathers at all. Closed covers and move one breather to the middle of the intake and vent the case in the valley instead. There is usually engough room between the carb and dist for a 1.5 NPT or O-ring fitting and 2" long hose to connect a breather. OR run that hose to elsewhere like behind the Midplate. There is more room in there, slower moving air-oil, and no worries about the stupid hole location being right on top of the rocker so oil is sent right up the tube.
    Its works great.

  5. #5
    Join Date
    Aug 2018
    Posts
    3,972

    Default

    We had a valve cover issue similar to what billet described. We couldnt figure it out, so we loosely folded a blue shop towel and stuck one in each breather. We changed them out every week, but it was a very mild issue. Problem solved.....cheap!

  6. #6
    Join Date
    May 2007
    Location
    in a van down by the river
    Posts
    1,822

    Default

    00 steel wool. Cut in, and pull it apart a bit so air will vent through. Insert it down the valve cover tube. The steel wool will keep the oil droplets low in the tube and not letting it flow up and out of the breather
    Just something that I done when I was pulling my hair out at certain race tracks that I would have an issue with oil out the breathers.
    I think there should be lifeguards in the genepool.

  7. #7
    Join Date
    Apr 2010
    Posts
    628

    Default

    just wanted to update, i took the old baffles out and bought some rubber ones that had bigger holes and it was completely dry saturday

  8. #8
    Join Date
    Sep 2009
    Posts
    723

    Default

    Are these rubber baffles designed to go into the tube of the valve cover or do they bolt into inside it?
    Picture or link?
    I'd never heard of rubber ones so I'm just curious.

  9. #9
    Join Date
    Apr 2010
    Posts
    628

    Default

    i run the fabricated all star valve covers, the baffle that comes in them is basically just a flared freeze plug. i drove the freeze plug out and push these down in the tube

    https://www.summitracing.com/parts/chp-jr149

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