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Customs Flathead 6 or Slant 6 Swap for 55 Dodge Truck

Discussion in 'The Hokey Ass Message Board' started by Flat Six Fix, Apr 4, 2018.

?
  1. 265 Flattie

    44 vote(s)
    67.7%
  2. 225 Slant 6

    21 vote(s)
    32.3%
  1. paintman27
    Joined: Apr 23, 2011
    Posts: 248

    paintman27
    Member
    from new jersey

    For my build I am still considering the slant six. Unfortunately the shop I want to use does not have a torque plate. For $600 I could have them machine one for me, but thats alot of danero for a one time use. Problem is I already have three /6's sittin in the garage for parts, so if I decide to go the V8 route I will have 3 paper weights sittin around waiting for a trip to the junkyard I guess. UGH!
     
  2. You do know spending money ay a machime shop doesn't guarantee perfect results. Expecially on old engines that the machinist doesn't work in very often. Your results are only as good as the machinist and his equiptment. Ive learned to avoid machine shops. If a engine needs rebored I set it aside and find one that will take a ring job. parts cost a couple of hundred at best. Now if I need a block bored. I take that block and the pistons to RHS in Memphis and wait and pay for a compentent machinist to do a perfect job.
     
  3. RodStRace
    Joined: Dec 7, 2007
    Posts: 2,149

    RodStRace
    Member

    I've got a 47 Chrysler with a flathead 6 and an A-100 with a slant.
    I don't know what your truck weighs, but did a quick search and it looked like you asked about that too and got ~3500 pounds answer.
    In something light (3K or less), I'd go slant. In a heavier, less nimble package (truck), that has a flatty OE, I'd lean :D toward the flatty.
    Torque rules on the street, especially in a heavier vehicle. I'd rather adopt a nice 5 speed to have more range than adopt a smaller, roughly similar output engine. Swapping to the slant is going to give up torque for more top end and probably a bit better mpg. It's more work for little to no pay back. If this was going the other direction (78 D-100 /6 swap to flathead), I'd also say no. I enjoy tinkering with things and making changes, but won't spend weeks making a lot of changes and getting issues resolved to achieve the same result. You mentioned no V8 and I understand and respect that. I also would not suggest a modern DOHC 4 turbo that has even better MPG and more high RPM HP. That just ain't right! Pull that 265 down, get it measured and price out the parts and machine work.
     
    Flat Six Fix likes this.
  4. mkebaird
    Joined: Jan 21, 2014
    Posts: 274

    mkebaird
    Member

    My vote's for the flattie. The 201" in my 39 is a jewel. Saved this truck from the crusher, never took the head or oil pan off!

    1939TC.JPG
     
    Hnstray and exterminator like this.
  5. dumprat
    Joined: Dec 27, 2006
    Posts: 2,169

    dumprat
    Member
    from b.c.

    I had a slant six in 61 1ton flat deck and a 251 flatty in an M37. The flatty was better hands down. And a lot better after I switched to dual carbs and a header.

    The slant six might be fine in a car.
     
    Flat Six Fix likes this.
  6. never had much experience with a slant six. Only one time I was coming down the hill by the ford garage with a load of hickory on my ford bob truck. theres a sharp left at the bottom . but you can go straight across and down to a garage attached to a house. The Thatch brothers had a 1ton dodge with a slant six. and had twenty fresh sawn RR ties loaded on it. they where up against a power pole rather than crashing into that house. no real damage but the dodge wouldn't back up. not enough power. I stopped at the bottom and backed down to them and pulled the dodge out backwards. later they decided to put a brick on the gas pedal and blow it up. And it never blew up just smoked and rattled until it ran out of oil and died. they added oil and it started up! they swapped a 318 into the truck.
     
    Flat Six Fix likes this.
  7. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    Thanx Rod yes the truck is near 3500 lbs and well as aerodynamic as a grain bin.
    Even with the tired 228 she will chug along in 4th gear at slower speeds and only a 1000 rpm now thats the torque factor.
    I'm patiently awaiting word on 2 other 265s and 1 is a low hour runner.
    If that falls through gonna finish the tear down and get some measurements.
    The shop im.using does a lot of old stuff including Chrysler flathead 6s. They did 5 this winter.
    Thanks for your comments.
    Heres a pic of my 47 Chrysler Royal.
    It had a long block Canadian 218 and 3 spd trans and no fluid drive coupler witha 3.73 rearend.
    Unfortunately had to sell in 2013 due to finances. I bought the car as a shell in 1988.


    Great engines and think of a well built 265 it has a lot of punch compared to the smaller displacement versions.
    Later 230s pack a lot more punch too.
     

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    Last edited: May 13, 2018
  8. RodStRace
    Joined: Dec 7, 2007
    Posts: 2,149

    RodStRace
    Member

    Nice!
    Mine has been sitting in the garage for a few years now. Fluid drive...
    Here's a pic from when I had just cleaned it up. More in my profile...

    [​IMG]

    If you want to talk aero, let's discuss the A-100! It's the shipping box your truck was stuffed in!
    Note this one is a V8, the 108 is the /6.
    [​IMG]
     
    chop job and Flat Six Fix like this.
  9. You already know my opinion on your engine swap! ;)
     
    Flat Six Fix likes this.
  10. treb11
    Joined: Jan 21, 2006
    Posts: 3,149

    treb11
    ALLIANCE MEMBER

  11. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    Massey Harris, White, and Cockshutt. Canadian built stuff had 250 or 265s, USA built could be the smaller 230 Industrial or a 250/265
     
  12. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    I know Brother I know...LOL
     
    59Bisquik likes this.
  13. I'll admit I don't know much about slant sixes so I really don't have an informed opinion on them one way or the other. I have owned a couple of the Mopar flathead sixes though and they seemed to be really stout. One time, unbeknownst to me, I lost a freeze plug in one. Puked out all the coolant. Heated that little flathead up so much that it seized. I let it cool off, replaced the freeze plug, and fired it back up. It continued running for years and never had any problems with it and never used any oil or knocked, and apparently nothing cracked from overheating. I have a lot of respect for those little flatties. So, you know which way I voted. :) That being said, don't let us decide for you. It's your truck and you need to determine what's best for you.
     
    Last edited: May 19, 2018
    Flat Six Fix likes this.
  14. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    Yes they are rugged old brutes.
    Slants ard near bullet proof tough too.
    In fact it ranks #6 of 10 all time best engines in the world.
    Gonna stick with a 265 flattie.
    Thanx for your post, story and vote.
    Alto or Tenor?
     
    Saxman likes this.
  15. Both. :)
     
  16. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    28 votes 265 flattie and 17 225 Slanty.
    Hmmm
     
  17. One more for the 265!
     
  18. paintman27
    Joined: Apr 23, 2011
    Posts: 248

    paintman27
    Member
    from new jersey

    I guess my only question is how hard is it to get parts for the 265 compared to the slant6? My concern would be stuff like the dizzy, water pump, etc. I know with the slants some stuff is hard to find, much less the Flathead.
     
  19. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    Not hard in the least bit.
    Waterpumps, fuel pumps, gaskets, you name it buy at local parts store or Rock Auto.
    Distributor I have lots of them and 1 already converted to electronic ignition using a Slant 6 distributor.
     

    Attached Files:

  20. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    The Slant 6 was if bourse a modern improved OHV engine.
    6 intake ports
    OHV
    Steel crank and rods
    Full flow oil filtration
    225 is fairly long stroke
    This engine ranked #6 all tyme best engines in the world.
     
  21. sunbeam
    Joined: Oct 22, 2010
    Posts: 3,959

    sunbeam
    Member

    If I remember right 27 and 92 Masseys used 230 super 92s used the larger engine.
     
  22. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    In Canada no shorter 230 INDs all 250 or 265.
     
  23. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    So 36 votes for a 265 flattie and 18 for a Slant 6.
    Thats 2 to 1..
    So how many of you voters have experienced both engine choices?
    Or those who did not post share why you chose which engine....
     
  24. Flat Six Fix
    Joined: Feb 6, 2010
    Posts: 879

    Flat Six Fix
    Member

    Hey all,
    Still have not built an engine yet.
    Still have a 265 candidate which would be coupled with truck 4spd and 3.23 diff.
    Or a 225 Slant 6, A833 Overdrive.
    I installed into an off topic import car but just yanked it out.
    Flatheads are kool, but Slants are bullet proof types and also can made to perform too.
     

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