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Technical Tapping in GoodWrench cylinder head

Discussion in 'The Hokey Ass Message Board' started by 1great40, Jul 10, 2021.

  1. 1great40
    Joined: Jan 1, 2008
    Posts: 471

    1great40
    Member
    from Walpole MA

    Hi all,

    I finally got to the point of firing off my new to me SBC 350 in my 40 Ford. After a short run, I let it cool and went to top off the coolant. That's when I saw a puddle forming on the floor under the right front of the engine. It turns out there's a tapping (I hope its a tapping) on the front of the cylinder head and the coolant is dribbling out from there. Is anyone familiar with this opening? What was it for and what size are the threads? I can't see directly into it because it's obscured by the serpentine belt bracketry.

    Thanks in advance
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 50,186

    squirrel
    Member

    there isn't anything there that touches water....unless you're lucky, and you got a head that someone drilled a hole into, so they could mount the wrong accessory drive system on it.

    Through 68 they heads didn't have any bolt holes. Starting in 69 they did. Check the back of the heads, if there are not holes, then someone drilled the front, and hit water.

    Or it's possible that the head had holes already, and someone bottomed out a bolt, or something.
     
    Tim, flatford39, fauj and 1 other person like this.
  3. 1great40
    Joined: Jan 1, 2008
    Posts: 471

    1great40
    Member
    from Walpole MA

    That may be the case, the hole is not in a faced(machined) area of the head, it just goes into the casting. in any event, it doesn't look like i've got a shot at it without removing the accessory drive
     
  4. Once you have access to it, put a pipe plug cap into the hole... hopefully it is threaded. Use a good sealer on the threads and you should be okay.
     

  5. Fordors
    Joined: Sep 22, 2016
    Posts: 3,943

    Fordors
    Member

    When you get everything out of the way can you post a photo of where the leak is?
     
    Blue One, Johnny Gee and squirrel like this.
  6. 1great40
    Joined: Jan 1, 2008
    Posts: 471

    1great40
    Member
    from Walpole MA

    Good morning!

    I messed around with trying to guess at the thread size and I finally took off part of the serpentine system. There are 2 tappings into the wet side of the head, probably for mounting some sort of belt driven gimmick. I can just barely get at the upper tapping, as I guessed, it's 3/8-16. Even with part of the serpentine system out of the way, I'll need to drill an access hole through the bracket to get an extension in there to tighten a bolt using a recently sacrificed 9/16 socket (don't worry, it wasn't Snap On). I'm going to have to inquire of the guy who originally installed this engine in a 48 Chevy.
     
  7. squirrel
    Joined: Sep 23, 2004
    Posts: 50,186

    squirrel
    Member

    You could get rid of all that serpentine crap, and run normal old brackets and belts, eh?

    I'm just speaking from the experience of a friend who bought a similar used belt setup, and ended up getting a new pair of heads to make it work...
     
    Desoto291Hemi likes this.
  8. I’m not quite certain what you mean by a “belt driven gimmick “,,,,,maybe,,,,,a serpentine belt drive ?,,,,,,Lol .
    Sorry,,, I couldn’t resist,,,,and besides,,,this is the Hamb !
    Those systems will always be the object of ridicule here .

    Take the parts off,,,,plug the hole with the correct size bolt,,,,with sealer of course .
    No more leak.
    It sounds like some genius got a hold of it before you bought it !

    Tommy
     
  9. 1great40
    Joined: Jan 1, 2008
    Posts: 471

    1great40
    Member
    from Walpole MA

    I took a picture but can't get it to my computer. There were 2 holes drilled into the head, both 3/8-16 both into water. Obviously used to mount something. I got 2 bolts with Permatex #2 into the holes and made up the bolts. Going back together now!

    I know folks don't like Serpentine drives here but that's what I have.If anyone is interested in why, I can post but it's pretty boring.
    Thanks to everyone!

    Tom
     
  10. Sorry Tom,,,,
    That’s the rules here,,,,,and I wouldn’t post too many pics of it,,,,or this thread will be locked .
    These guys let a few posts go by,,,but eventually they “call the ball “,,,.

    Tommy
     
  11. Budget36
    Joined: Nov 29, 2014
    Posts: 7,497

    Budget36
    Member

    A Goodwrench engine would have had all the necessary accessory holes already in the heads. Have you checked the head casting number to see what you have?
    I know some people “have a better idea” but I don’t see a reason to drill and tap them if they are “modern” heads.
     
    olscrounger likes this.
  12. 1great40
    Joined: Jan 1, 2008
    Posts: 471

    1great40
    Member
    from Walpole MA

    Everything is fixed! Thanks to everyone who helped out. Like Squirrel mentioned, the back of the drivers side head should be the same as the front of the passenger side, and it's not. I'm told the engine has never been apart and its got 25 K on it, it's over 20 years old. Obviously the holes were put in at some point after the engine was manufactured. Another giveaway that the holes were added is that the surface of the casting where the holes are, hasn't been machined, or spot faced to give a square smooth surface for a bolt to tighten on. That sort of bugged me when I installed the bolts but they're not leaking. My only alternative would be to drill them out and tap them with a pipe thread and use a pipe plug as BobSS396 mentioned.
    On to the next hurdle!
     
    dirty old man and Tim like this.
  13. Good deal man,,,glad it worked .
    I started to mention earlier,,,you could have used a set screw,,,,,that would have screwed in flush .
    But bolts work fine,,,,and I’m sure the bolt head will not be visible to the casual observer .

    Tommy
     

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