What are these holes??????
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500, 472, 425, 368 Discussion, What are these holes?????? in Cadillac Engine Technical Discussion; I have a 75 500 that came out of a Sedan Calais and was replacing the gaskets. When I put ...
  1. #1
    lead sled is offline Cadillac Owners Member
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    What are these holes??????

    I have a 75 500 that came out of a Sedan Calais and was replacing the gaskets. When I put the heads back on I noticed that there was a hole that I didn't remember being there when I took the heads off. It's really strange. If I look in the hole it runs all the way through the head, like somebody put a pipe that runs the length of the head from front to back. Both heads have this same feature. I took alot of digital picutres but can't find a good picture that shows what was there to begin with. I also don't remember removing (4) plugs either.


    Anybody know what these are for or what to do about them now???

    Thanks Wayne

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  3. #2
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: What are these holes??????

    Sounds like the A.I.R. injection setup to me. Was the car equipped with an A.I.R. pump? They use a crossover tube between the front of the 2 heads. The tube is held in with a Crow's foot gizmo similar to that used on a distributor but smaller.

  4. #3
    caddydaddy's Avatar
    caddydaddy is offline Cadillac Owners Connoisseur
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    Re: What are these holes??????

    I'm sure all 500's of that era had AIR injection. You can just thread it for a pipe plug, or re-use the system.
    On my 1972 472 I had the holes in the valve ports filled and the intake on the end of the heads was plugged.

  5. #4
    The Ape Man's Avatar
    The Ape Man is offline Cadillac Owners Connoisseur
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    Re: What are these holes??????

    Quote Originally Posted by caddydaddy
    I'm sure all 500's of that era had AIR injection. You can just thread it for a pipe plug, or re-use the system.
    On my 1972 472 I had the holes in the valve ports filled and the intake on the end of the heads was plugged.
    Unless you happen to live in Kali-fornia.

  6. #5
    lead sled is offline Cadillac Owners Member
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    Re: What are these holes??????

    No there isn't an A.I.R. pump. There was a big diaphram on the passanger side exhaust with a tube running to the front of the engine, but nothing on the driver side.

  7. #6
    caddydaddy's Avatar
    caddydaddy is offline Cadillac Owners Connoisseur
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    Re: What are these holes??????

    The valve on the exhaust I believe is called the EFE valve. I think it runs off of engine vacuum, and that's the line you saw. The emmissions label should mention whether there was an AIR pump to begin with. Most likely it was removed.

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