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Technical Olds Valve Cover gasket quandary

Discussion in 'The Hokey Ass Message Board' started by Humboldt Cat, Jul 12, 2020.

  1. Humboldt Cat
    Joined: Feb 20, 2003
    Posts: 2,231

    Humboldt Cat
    Member
    from Eureka, CA

    Been hard pressed to find the correct 5-bolt hole gasket for the 70's Olds 350 in my kustom... have had to settle for more common multi-bolt hole gasket, eventually leaking.
    Anyone recognize the particular year/model of this? Was it just a unique 5-hole model they ran?
    Have googled w/o success. Tryin to recover stamp ID info of years past.
    Thanks for any help.
    IMG_20190330_091704_819.jpeg

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  2. onetrickpony
    Joined: Sep 21, 2010
    Posts: 456

    onetrickpony
    Member
    from Texas

    They eliminated the extra bolt holes and glued them on with RTV from the factory, no gasket. They were bad about leaking even then.
     
  3. ^^^^^^^^^^^^^^^ what he said
     
  4. You can see the xtra dimples/bosses for the other bolt holes that are not there, If the heads are drilled for the holes find valve covers to fit
     

  5. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    It's what we call "late model junk"
     
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  6. Humboldt Cat
    Joined: Feb 20, 2003
    Posts: 2,231

    Humboldt Cat
    Member
    from Eureka, CA

    Heads have same # of holes.
    Before this mill, I had a '72 Olds in it, had the several bolt holes in it.

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  7. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,423

    OLDSMAN
    BANNED

    IMHO I would use a valve cover gasket as a pattern and drill the remaining holes into the valve cover. That should correct your leakage problems. As far as I know all the heads have all the holes drilled and tapped in them from the factory.
     
    Last edited: Jul 12, 2020
  8. Humboldt Cat
    Joined: Feb 20, 2003
    Posts: 2,231

    Humboldt Cat
    Member
    from Eureka, CA

    Went back to the shop to recover stamped ID info... a source online had 3A stampings for 1979 heads, 3rd pic is the engine ID stamp on the flange near cylinder #1 at front left, I believe it's from 1977. Tried a combo of years n models through Summit & Rock Auto, no match for the 5-hole pattern in the heads. Will have to try again for a good seal.
    Oldsman's suggestion is interesting, is it to just screw/fasten gasket to flange/blank 'ear', when it's not over any head metal? 20200712_124855.jpeg 20200712_125248.jpeg 20200712_131051.jpeg

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  9. AHotRod
    Joined: Jul 27, 2001
    Posts: 11,149

    AHotRod
    Member

    This is the only sealant that we have found that will keep things sealed up, and we work on Hot Rods and Muscle cars all day long. We use this to seal the new gasket to the surface and to the head.

    s-l500.jpg
     
    Last edited: Jul 13, 2020
    5window and egads like this.
  10. CA383A23-A914-4095-B625-C5F66E4C7E3D.jpeg You may also consider using Corvair valve cover hold downs.
     
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    I'm not really sure what you were looking for, but if you are looking for pictures of heads with 5 valve cover bolt holes, just go to google and search images for

    olds 307 head

    and you should find plenty...I did...

    head.jpg

    If you were searching for gaskets with only 5 bolt holes, you probably won't find any.

    The "right stuff" suggestion above is probably where you'll end up. Sorry. Although I'd see about trying some Fel Pro cork 10 bolt gaskets, if you can get them. rockauto lists them, 5 bucks a pair, plus postage.
     
  12. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,423

    OLDSMAN
    BANNED

    Like I said get a valve cover gasket for a 1973 year engine and use it as a pattern to drill the holes in the later valve cover. That will get you the holes in the correct places to match the threaded holes in the cylinder heads
     
  13. onetrickpony
    Joined: Sep 21, 2010
    Posts: 456

    onetrickpony
    Member
    from Texas

    Not only are there no bolt holes in the head, the bosses needed to drill and thread them are not there.

    Cat, your best bet is to just use Right Stuff. Make sure the cover gasket surface is as flat as you can get it, put a thin layer on both the cover and the head and let it tack up before installing. Don't over tighten it.

    If you use a 10 hole gasket, use cork and fill the extra bolt holes with RS. Thin layer of RS on each side.

    Some gaskets have metal rings around the bolt holes or inserts in the gasket to keep it from being squeezed out. Try to use those if you can find them.
     
  14. As stated above.. he does not have the xtra thread holes in the cylinders
     
  15. OLDSMAN
    Joined: Jul 20, 2006
    Posts: 2,423

    OLDSMAN
    BANNED

    I was under the impression that all Olds heads had the holes, just not in the valve cover
     
  16. squirrel
    Joined: Sep 23, 2004
    Posts: 47,441

    squirrel
    Member

    did you see that picture I posted above? late model junk heads....they quit putting the holes in them, and the bosses for the holes.
     

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