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21 stud question?

Discussion in 'The Hokey Ass Message Board' started by Johnyeyeball, Mar 22, 2013.

  1. Are the ford made aluminum heads any higher in compresion than the steel ones? The chambers are very diffrant
     
  2. Carter
    Joined: Mar 18, 2006
    Posts: 1,405

    Carter
    Member

    Johnny, the heads on those engines can be either for the dome top pistons or flat top pistons. I believe dome top pistons were only used in 35 and later engines. What is the part number on your aluminum heads?
     
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  4. ukgav
    Joined: Jun 16, 2008
    Posts: 301

    ukgav
    Member

    Just had a look at the Ron Bishop book.
    States that stock heads give 5.5:1 CR and 65bhp and aluminium give 6.3:1 CR and 75bhp.
    Also says dome pistons were introduced in 37 along with the water outlets being moved to centre of the heads.
    Vanpelts has the same info.
    http://www.vanpeltsales.com/FH_web/flathead_specs-85early.htm
     
  5. 40- i belive means its a 1934
     
  6. thank you soo much
     
  7. ukgav
    Joined: Jun 16, 2008
    Posts: 301

    ukgav
    Member

    Of course if you are feeling spendy then Don Orosco can fit you out with a set of heads that give around 8.25:1 CR. ;)
    [​IMG]

    These are fitted to my motor although I bought heads meant for dome pistons by mistake as I have flat tops. They still bump CR up to around 7.25:1 and give me the option of fitting dome slugs at a later date.
    Have fun with the motor, I love mine.
     
  8. Carter
    Joined: Mar 18, 2006
    Posts: 1,405

    Carter
    Member

    40 prefix indicates first year used being 33. Those heads were used 33-6 for flat top pistons.

    48-6049 and 48-6050 are the 35-6 aluminum heads for dome top pistons.

    What are the iron heads you were comparing those to?

    Sent from my DROID device using the TJJ mobile app
     
  9. the motor is a 34 and has flat top pistions so i think im in the ball park.
     

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