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Technical Buying a Flathead - What to look for?

Discussion in 'Traditional Hot Rods' started by Pontiac787, Jun 9, 2019.

  1. Pontiac787
    Joined: Jun 8, 2019
    Posts: 3


    Hi All,

    I'm looking to buy a flathead as the basis for a looooong term Hot Rod project. Can you offer any tips on what I should look for when checking out a complete engine? I've found a few complete 8BA engines in my area that appear to be well cared for and stored in-doors. I'm thinking it will be more cost effective to buy a complete engine (providing the price is right) and upgrading as I go as opposed from starting from a bare block.

    I tried the search function but couldn't find the right combination of key words to find what I was looking for. If this has been covered before feel free to point me in that direction.

  2. Dirty Dug
    Joined: Jan 11, 2003
    Posts: 3,549

    Dirty Dug

    Don't buy it without pulling the heads to assure there are no cracks in the decks between the water passages and the valves and check the bores for excess wear. That also gives you a chance to measure the stroke and look for any indications of a rebuild.
    Flathead Dave likes this.
  3. Correct, don't buy without pulling the heads, you don't want to see water in the cylinders or any cracks. HRP
  4. 51504bat
    Joined: May 22, 2010
    Posts: 1,108


    Check the pan rail for cracks as well. Cracks around the head bolt holes are pretty common, so much that some say they came with a Ford part number. Not all cracks in the valve area are fatal but the cost to repair depends on the extent of the crack(s) and the number. Start with a complete engine if at all possible so you have all the needed parts to start with. You can always up grade as your build progresses.
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  5. You will want to Magnaflux any block before you put much money into it. It may require that you purchase several engines before you find a good block. Try to get a money back deal with the seller if the block has cracks which cannot be easily repaired.
    alanp561 likes this.
  6. Let's jump ahead a little. What vehicle are you going to put the engine into? Some combinations are easier than others.

    Charlie Stephens
    Flathead Dave likes this.
  7. leon bee
    Joined: Mar 15, 2017
    Posts: 299

    leon bee
    from Arkansas!

    The reason everyone has said what they did is because so many of the blocks are cracked. Even if the engine has been running those cracks can be there. At this point, the block is about your only real concern because everything else is easily available. If you find a seller who is knowledgeable about these engines, he should expect you to want some disassembly prior to sale.
  8. acme30
    Joined: Jun 13, 2011
    Posts: 136

    from Australia

    The other area to look for cracks is between the centre crankshaft web / support and the cam. This area is usually very dirty and oily so you often can't see cracks there until the block is cleaned and the crankshaft removed. I am led to believe if there is a crack there your block is toast and not suitable for any performance applications.
  9. 41rodderz
    Joined: Sep 27, 2010
    Posts: 2,739

    from Oregon

    In other words , it may not be all cracked up to be what you are hoping for.
    clem likes this.
  10. belair
    Joined: Jul 10, 2006
    Posts: 8,018


    Probably another flathead.
    kidcampbell71 likes this.
  11. 1pickup
    Joined: Feb 20, 2011
    Posts: 818


    The first thing to look for, is the other 42 threads asking this same question...
    kidcampbell71 likes this.
  12. 19Fordy
    Joined: May 17, 2003
    Posts: 6,339


    I don't recommend the loooooong term build approach as the cost for building a flatty
    will only keep going up.
    Texas Webb likes this.
  13. clem
    Joined: Dec 20, 2006
    Posts: 2,341


    and yet no help in directing him there........ even though he politely asked.
    Last edited: Jun 10, 2019
  14. clem
    Joined: Dec 20, 2006
    Posts: 2,341


    Doesn’t always show up what you are looking for.
    Do a google search and include the word HAMB in your search, seems to be more effective at times.
    Flathead Dave, lake_harley and i.rant like this.
  15. Pontiac787
    Joined: Jun 8, 2019
    Posts: 3


    Thank you all for the info and the help with the search function. When I said long term I meant the overall project, hopefully not the engine. I want the engine to go into a steal bodied A but I’m on a budget so there is no hurry.
  16. banjorear
    Joined: Jul 30, 2004
    Posts: 3,745


    This. Recently, it took me 5 blocks to find one good one. Bottom line, unless it's running and driving, do not pay more than $100-$200 ($300 at max) for a complete engine. Even a running engine can be cracked, so running, driving isn't always the best indicator either.

    More than likely, the only things that can be re-used will be rods, crank, block, starter, generator. Heads and intake if wanting to run stock stuff.

    8BA style can be a little easier to tear down since they have bolts instead of studs. Even bolts can break off and cause a headache. Go slow and use heat and a lot of Kroil or 50/50 mix of ATF & acetone.

    Once torn down, the block must be cleaned first and then magnafluxed. If it checks out to be good, I would also suggest getting it baked and blasted to get all the crud out of the water jackets.

    You can help the process by prodding all sorts of pokers, etc. into the water jackets, but this is an crucial step in order to get a cool running flathead.
    Flathead Dave likes this.
  17. fullhouse296
    Joined: Jan 30, 2009
    Posts: 355

    from Australia

    No cheap way to rebuild a flathead ,and thats way before you start getting speed gear (price just trippled) .I dont even drag a free one home without pulling the heads in the paddock ,.Take acetone ,rags ,120 grit sandpaper ,some wet chalk and a torch .
  18. Torana68
    Joined: Jan 28, 2008
    Posts: 1,074

    from Australia

  19. Some good suggestions here. One of the first things I'd be thinking about is WHAT year/type of flathead will best fit your project? There are trade-offs related to water pump belt locations, distributor location and overall fitment into Model A's. It is usually easier to fit a 39-48 flathead (with the fan belt close to the block) and the front-mount distributor, than a 49-53 with the side-mount distributor and a crank pulley and belt setup that moves the belt out a couple inches from the block. You can 'retrofit' a 49-53 block to use the earlier heads, earlier water pumps, timing cover, etc -- but you need to know where you're headed with this stuff when you make purchase decisions.

    If you're trying to buy complete engines, then it is super important to pull the heads and inspect the block as best as your can. Some sellers want nothing to do with this . . . others will work with you. Some sellers are willing to "guarantee the block is good" - or maybe refund some of your money if it doesn't pass a mag test. There are plenty of cracked flatheads out there . . . and truth be told, I seem to see more cracked 49-53 blocks than 59A-B blocks (just my own experience).

    If I'm thinking of buying a engine or block, I take an assortment of wire brushes and lacquer thinner with me such that I can clean the heck out of the "transfer area" between the valves and the bores - looking for cracks (very common). In many cases this was due to severe overheating of the engine - causing cracks to generate around the valves, sometimes INTO the ports and into the cylinder bores. Personally, I don't build engines from cracked blocks - though many people do. I put way too much time into porting, valve work and performance block work to justify the gamble of fixing cracks and praying that they hold. (Many guys do fix cracked blocks - me, I try to start with non-cracked blocks on performance builds).

    I also clean the heck out of the oil pan rails and look for cracks down there. Many flathead block were cracked because there are no freeze plugs and engines that froze (in the car or not) can easily crack the thin pan rail areas as a result. You usually can't tell there is an issue unless you pull the pan.

    So, what this all means is that you need to be prepared to go through a few engines, tear them apart, potentially find a few cracked ones and ultimately get to a good one. This is why if you can find a good, cleaned and magged block (with a guarantee) for $750 - $1000 just buy it! Then build a great engine around a great starting point . . .

    If you have any questions related to the above, just PM me - be happy to point you the right direction in relation to "what works with what" . . . and all the gory flathead details involved.

    Take care,
    kidcampbell71 likes this.
  20. good advise Dale...................
  21. 5window
    Joined: Jan 29, 2005
    Posts: 6,728


    Flathead Dave likes this.
  22. The advice of finding somebody who really knows their stuff - is spot on. Now whether they'd be "ahead" or not - depends on the size of their wallet and associated expectations! :)
  23. tubman
    Joined: May 16, 2007
    Posts: 4,190


    You said it all right there.
  24. Pete1
    Joined: Aug 23, 2004
    Posts: 1,642

    from Wa.

    "I would also suggest getting it baked and blasted to get all the crud out of the water jackets."

    ONCE AGAIN, I have to comment on this.
    Baking and shot blasting will NOT get rust and scale out of the bottom of the water jackets.
    The ONLY thing that will is acid stripping.

    Ultra sonic testing with comparison readings to a stripped block is the best way to know what is in the areas that can't be seen.

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