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Hot Rods head gasket question

Discussion in 'The Hokey Ass Message Board' started by jaxx, Aug 1, 2020.

  1. jaxx
    Joined: Mar 22, 2008
    Posts: 385

    jaxx
    Member

    I have a 1986 - 318 that I am putting in my RPU - I'm fixing to have the heads done on it prior to install and was wondering if anyone would know if opening the hole in the head gasket that blocked the water from circulating between the head and block on this year model would cause any problem ? - I know that they blocked it with the head gasket to bring the heat up for all the smog crap in those years but did not prior to 72 I believe - I have all the smog crap off of the engine now -- any input would be helpful - jaxx
     
  2. Mike VV
    Joined: Sep 28, 2010
    Posts: 2,055

    Mike VV
    Member
    from SoCal

    Put it in place and don't worry about it.
    Most if not all head gaskets have holes blocked or mostly blocked vs. the size of the holes in the block and or heads. The small Chevy has about a 3/4 hole in the block, the gasket has one, sometimes two 1/8" dia, holes it the 3/4" location.

    If coolant flows too fast, it won't stay in the radiator long enough to transfer the heat out of the coolant to the radiator.

    Mike
     
  3. squirrel
    Joined: Sep 23, 2004
    Posts: 46,847

    squirrel
    Member

    If the hole is at the back of the engine, it needs to be open. If it's at the front, it needs to be closed. You want coolant to move from the water pump, through the block, then up to the head, then forward. If you open up a big hole at the front, it will take the path of least resistance, and just go to the head at the front, and never cool the rear of the engine.
     
  4. jaxx
    Joined: Mar 22, 2008
    Posts: 385

    jaxx
    Member

    the hole is at the front on the passenger side - so i will live it in place - thanks for the info - jaxx
     

  5. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 1,441

    ekimneirbo
    Member
    from Brooks Ky

    I'm not a Chrysler guy so I don't know specifics on them. If you look at the top of your block where the head sits, you will probably see that there are many open tops to the waterjacket that do not pass water to the heads. You may see some that are only blocked off by the head gasket as opposed to the head itself. The question is how to create flow that works, and I can't answer with a blanket comment for all engines. On some 500 Cadillacs guys are working to get temperatures lower because many of them run hotter than preferred when installed in other vehicles. On the Cad there is a rather small hole at the rear of the block. The hole allows water from the block to move up into the head. Some have experimented with enlarging this hole slightly and adding a couple of extra small holes. This seems to be sufficient for cooling the engine. I think the idea is that the water needs to circulate from the rear to the front rather than possibly circling up too much at each cylinder and the water in the rear never completes the cycle back to the front. Again, I "think" thats what is happening. The gasket manufacturers must have a reason for blocking passages.
    Cadillac Cooling Mod 1.jpg

    DSCN2261.JPG
    Drilling Cad 1.jpg
    Drilling Cad 2.jpg
    Drilling Cad 3.jpg

    Anyway, this is what some people are doing to 500 Cads if thats any help.
     
    Last edited: Aug 2, 2020
  6. squirrel
    Joined: Sep 23, 2004
    Posts: 46,847

    squirrel
    Member

    Different engines work different ways. Most Fords have holes at both ends of the block and heads, and you have to put the gasket with the word FRONT at the front, so the front holes are blocked. Chevy just puts the correct holes in the block, and you can put the gaskets on either way. Mopars and Caddys are strange...
     
    ekimneirbo likes this.

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