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Flathead Tech

Discussion in 'The Hokey Ass Message Board' started by Flatdog, Mar 4, 2008.

  1. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    I an posting some pics showing the difference side to side in late flathead .
     

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  2. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    More
     

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  3. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    (the basic valve angles dictating side differences would be as shown 1946-53, all the commonly used engines. Earlier engines are spread a bit more.)
     
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  4. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    I am going to try to explain some stuff .I doin't think difference in port shape means much after you port.Some of these pics are stock ports some are modified.If you study them you will see that stock ports need to be opened around valve guide.IMO. None of what your seeing it cutting edge stuff but it will help you very much to build a nice running flatmotor.This info is only part of the whole picture you must have all other parts of the motor working together.Hope this helps.
     
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  5. Casey
    Joined: Nov 8, 2005
    Posts: 3,293

    Casey
    Member Emeritus

    man you guys from jersey sure know how to blow up a motor ! :)
    great info , and great talking with again this afternoon .
     
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  6. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    I was trying to figgerout how to measure or otherwise describe those differences (see Thickstun offset discussion!)...now I can see the utter hopelessness of describing them even more clearly!
    Thanks for the great pictures!
     
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  7. R Pope
    Joined: Jan 23, 2006
    Posts: 3,309

    R Pope
    Member

    Has anybody ever come up with a good explanation of why Henry did that? There must have been a logical reason.
     
  8. jetmek
    Joined: Jan 12, 2006
    Posts: 1,846

    jetmek
    Member

    could you please explain your reasons? some feel that simply matching the bowls to get consistancy in the volumes and actually adding some to the floor of the runners to keep velocity up is a significant improvement
     
  9. Vergil
    Joined: Dec 10, 2005
    Posts: 785

    Vergil
    Member

    Thanks Flatdog, love those cut aways, shows it well

    Vergil
     
  10. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Who does some refer to? I think adding to port floor in what I am gonna call the belly area would be a benefit.I have also seen many porting jobs that have been opened up in that belly area which I think is wrong.
     
  11. blown49
    Joined: Jul 25, 2004
    Posts: 2,212

    blown49
    Member Emeritus

    Flatdog, the tape picture for the short port is kinda fuzzy but the long dimension appears to be about 2.500 from the deck, what is the short dimension??

    And thanks for the pics!

    Jim
     
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  12. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Short runner I got 2 inch. Thinking again you also have to take transfer area when fidgering port length.I wouldn't make a big deal about all of this .Think it wrong place to spend a lot of time .
     
  13. Digger_Dave
    Joined: Apr 10, 2001
    Posts: 2,517

    Digger_Dave
    Member

    Wow! That must have taken a whole bunch of band saw blades to cut those up!!
    Those are the first ACTUAL cross section pictures I have ever seen, of the "air/fuel path" in a flat head.

    It's interesting to see how the two cooling passages come close to the the runners.
    With those pictures in hand; it will be easier to avoid grinding into them.
    It's kinda like having an x-ray of them.

    Shaping (tapering from top to runner) the tops of the valve guides - for good flow - would appear to be different from one side to the other. (left to right)
    Most information I have, treats both sides the same

    Any words of wisdom on how you have been doing them??
     
  14. blown49
    Joined: Jul 25, 2004
    Posts: 2,212

    blown49
    Member Emeritus

    Thanks Flatdog just trying to verify the approxamate length difference.
     
  15. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Dig,Broke them apart with sledge hammer till I could lift and hold on chop saw.Yes lot of work and danger. Yes you need to see where water dwells to port. I treat both side the same.A couple of the pics are of good ports.But I think last job done with keyed guides is probbally better.
     
  16. sodbuster
    Joined: Oct 15, 2001
    Posts: 4,957

    sodbuster
    Member
    from Kansas

    Neat info............thanks.
     
  17. no bux rod
    Joined: Mar 26, 2007
    Posts: 123

    no bux rod
    Member

    Flatdog,

    I need to do the same with a Chrysler flathead 6. Thanks for the cutting tips. Did you use a chisel at all to score the blocks before you used the sledge? That seems like a better plan than finding a 5 HP industrial bandsaw, two guys and a hoist.

    N B R
     
  18. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Nope just whacked away .The voivces in my head told me where to hit.
     
  19. A picture is worth a thousand words! Thanks for a lot of hard work!!

    What would you recommend to fill the belly area, any block repair epoxy?

    Does the porting in front of the guide and tapering the guide help in any way to smooth the flow on the backside of the guide and port? Looks like a virtual 90* dead end turn there, and that some sort of radius would make the transition cleaner. Maybe build up the back top on the guide, or radius it concave front to back? Would it stay in position? Or would it matter? Just thinking out loud.
     
  20. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    What would you recommend to fill the belly area, any block repair epoxy? # 1 Yup. #2 If I told you to much more I have to wack you .Good thinking but hard to do...... But not impossible.
     
  21. hmmmmm...so that's (#2) do-able? Ha, c'mon, spill the beans. Modify the guide or the wall or both? Leave the guide high on the back, slopeing to the front? Don't want to steal any "speed secrets"
     
  22. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    Yes you do. Everyone does.
     
  23. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    I think this answers a lot, actually.

    One clarification request & one question - when you say "belly" I assume you're referring to the bottom (as shown in your pics) - yes?

    Question - how did you key your guides?
     
  24. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,440

    Kevin Lee
    Super Moderator
    Staff Member

    Looks like you could do it right through the lifter valley - sort of like drilling holes for the punch on an adjustable lifter? Might take a pretty creative tap wrench but maybe you drill and tap to 10/32 allin one shot with the guide in place? All guess work here - just looking a running on at the mouth.

    A crazy person with access to a machine shop with an affinity for small interesting jobs could even come up with custom guides. Pre-shaped to fill in the majority of the port belly? Fill in the rest with block repair epoxy.
     
  25. Ernie/Kevin, you're right! I missed that one sentence on the earlier post. Doesn't say that it has to be a "square" key, does it? Maybe drill/mill a vertical hole with the guide in place, centered on the guide/wall mating surface and pin it from the top? The old 8d nail trick. Build up the back of the guide to make the radius.
    Voila.

    Kevin's idea sounds easier from a machining standpoint; sort of a set screw into the valley side of the guide, right?
     
  26. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    Kevin - you'd be drilling up if I'm following you...short, compact right-angle drill maybe?

    Almost seems easier to drill straight down from the valve bowl. A true masochist would broach in a square key though! ;)
     
  27. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    There are clues in an early 1960's flathead racecar feature involving a famous old builder in HRM...
     
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  28. Sooooo, what issue might that be in?;) Mine only go back to '64.

    Pay-pal, money order or Nigerian bank cheque?:D
     
  29. gas pumper
    Joined: Aug 13, 2007
    Posts: 2,956

    gas pumper
    Member

    A square key could fall out? I think.
    I'd drill a round hole, split between the block and quide. ream for a press fit on a dowel or a spring roll pin. Used to call this operation a "Dutch Pin"

    Frank
     
  30. Flatdog
    Joined: Jan 31, 2003
    Posts: 1,285

    Flatdog
    Member Emeritus

    Maybe if enought of you guys speak up I can come up with some new ideas to try.
     

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