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Technical Rebuilding a flat head motor

Discussion in 'The Hokey Ass Message Board' started by iceteacharlie, Oct 23, 2018.

  1. I know enough about rebuilding a small block Chevy to be dangerous and have rebuilt a small block Ford with some oversight a gazillion years ago.

    There is just something about looking at a flat head motor that really makes me want to rebuild one for a future project (which I don't have just yet). Don't know what the pull is to do so- maybe it's simply in the DNA/roots? of my love for old cars.:confused:

    How does a flat head rebuild compare to a modern V-8? Basically the same? Simpler? More complex?
     
    Truck64 likes this.
  2. khead47
    Joined: Mar 29, 2010
    Posts: 1,789

    khead47
    Member

    Look at it as 8 Briggs & Stattons.
     
    stillrunners and alanp561 like this.
  3. Thanks Chappy! Those links did 2 very important things for me...
    1) It makes me feel good about sticking with SBC's :D
    2) It gives me an even greater appreciation when I see them in someone else's rod! :)
     

  4. Don't give up on the flathead.
     
  5. alchemy
    Joined: Sep 27, 2002
    Posts: 20,404

    alchemy
    Member

    Buy a good book and pay attention to the crank's sideways offset, and the two sides of the valve angles don't match. Lots of weird angles on a flathead.

    And don't deck it unless it absolutely needs it. And don't use a regular cutting tap on the head stud holes, or you WILL have leaky studs.
     
  6. MARKDTN
    Joined: Feb 16, 2016
    Posts: 147

    MARKDTN

    I had a good local machine shop with a guy who really knows them. I had him install the cam and valves since I didn't want to buy the tools for them. I built the rest of it, after the valves, it's not much different than a SB. Just torquing bolts. Mine is the later 8BA so I did not deal with babbited bearings, that would have been much more difficult. Finding a good block is probably the hardest part. My original block would have had to go .125 over plus 2 sleeves and a couple cracks. He found me one that went .030 over, no sleeves, and fixed 1 crack. I deal mostly with non-HAMB cars, but there is something about a flathead that is quite nostalgic (mine is in a 1942 Ford 2N tractor). If you want to do one and you can build a SB, then go for it, but I would stick with an 8BA or French engine.
     
    Texas Webb likes this.
  7. Well, they're the same only different. They use less parts but take the same 3 things to get the same results out the end of the Crankshaft as a S.B.C. My outlook is this, Fun costs $$$$ and often lots of it. Building a Kool ride should be a personal thing, not to please the onlookers. You can't build your Vision of Fun on a budget. A Budget built Hot Rod is a disappointment. If you want a Flat Head dive in and do it. It's only $$$. Any of that you leave behind will get spent fast by someone else for what ever they think is Fun. We can't have that! Go find yourself a Core and while your building it you will decide on something to put it in.
    The Wizzard
     
  8. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    I guess that depends on the vision...there a whole bunch of fun things you can do on a budget.

    I haven't built a flathead Ford, but I did a budget overhaul on a Caddy flathead V8 for a couple hundred bucks. It runs great.
     
  9. Cut costs where you can. I too felt a need in my DNA to rebuild a Flathead. At the end of the day, and after a few grand $$$, I've never really been happy with it. That is not to say it's a bad motor; in fact, it's impressive- it's castings are amazing, the sound is unbeatable, etc.

    If I had it to do again, I would have just freshened up my tired flathead with a cam and a dingleball hone and some bolt ons. Aluminum heads and some of the bling weren't really necessary. It's easy to get carried away and spend a small fortune.

    Head to the Fordbarn and look for Walt Dupont and Ol' Ron. There's is Flathead gospel.
     
  10. I think it also depends on how you describe "Budget". I have heard to many people say I have X number of dollars saved up and I'm build a - - - - without having anything to start with and making poor choices when they do find parts. Soon they are half way in and the Budget is gone. That is not saying everything needs to be New inside a Motor. There is a wide margin between used and used up. You my friend,, are one of the Few that gets a lot of miles out of his dollars spent with good hands on application and good knowledge.
    I followed that Caddy overhaul. You didn't cut any corners but didn't build a brand new motor, just made and old motor run well again. Had that motor needed more done I think you would have done what ever it was and not just stopped because of a Budget.
    I always admire your work and pay close attention to your advice.
    The Wizzard
     
    GreenMonster48 likes this.
  11. squirrel
    Joined: Sep 23, 2004
    Posts: 55,931

    squirrel
    Member

    "doing a valve job the old way" or something is the name of the thread.

    but yeah, I cheated, the engine had been rebuilt several decades before.
     
    cactus1 likes this.
  12. Smiffy
    Joined: Dec 30, 2014
    Posts: 150

    Smiffy

    Unless you score an engine that is a good runner for a reasonable price and you can dress up a bit be prepared to spend big $$$, also finding someone who knows them. If you are budget conscious and want bang for buck stay with OHV I have built flatheads in the past and in a weak moment recently priced one to fully rebuild with race cam, heads etc. Cost twice as much as an OHV to build and OHV produced three times more HP. After all that I still have a soft spot for them but my budget hates them.
     
  13. 51504bat
    Joined: May 22, 2010
    Posts: 4,754

    51504bat
    ALLIANCE MEMBER

    When it was all said and done I had over 4 grand in my 8ba build but that included a new Brassworks radiator. Engine is completely stock and didn't require any crack repairs. It was Sonic tested and magnafluxed prior to boring. EAB heads and a Merc cam and new French rods from SoCal. Crank only needed a polish. Installed used adjustable lifters from a friend. Not a powerhouse but wouldn't trade it for a newer overhead.
     
    Texas Webb likes this.
  14. dan c
    Joined: Jan 30, 2012
    Posts: 2,520

    dan c
    ALLIANCE MEMBER

    i got hooked in the '70s because i was a shade-tree mechanic and people gave 'em away back then. nice and torquey and a sound like no other!
     
  15. Garpo
    Joined: Jul 16, 2016
    Posts: 292

    Garpo

    Some love 'em, some hate 'em, but the flatty lives on. Best advice I can give is to buy several of the "How to build a flathead" books that are available. All have their own take on the how to, but the different opinions are all worth considering. Not quite a 'how to' is John Lawson's "Flathead Facts", but it does provide lots to think about.
    Remember when rebuilding something from the 30s 40s or 50s that has been touched up a few times, there are no short cuts. Do it right. Do it once.
    Then drive it.
    Garpo
     
  16. Lots of cool things to think about. I appreciate all the input.
    Rod On!
     

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