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54 331caddy vs.55 331 caddy

Discussion in 'The Hokey Ass Message Board' started by studillac tom, Apr 1, 2013.

  1. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
    Member

    Anyone help me out with the reason why a 54 331cu in caddy has 230hp and the 55 331cu in caddy has 250hp I have a 54 Bill Frick Studillac rebuilding the eng. and would like the extra 20 hp. I also have tri power so maybe I'd wind up with 260hp Could it be heads and if so could my heads be modified to 55 specs.?
     
  2. dangulo
    Joined: Feb 11, 2012
    Posts: 52

    dangulo
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  3. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
    Member

    Thanks skidmarks This is a period piece (54 motor 54 car) the 390 heads may fit but my value covers won't fit the 390 heads
     
  4. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,585

    HEATHEN
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    from SIDNEY, NY

    ???????? '54 valve covers will fit heads through 1962.
     
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  5. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
    Member

    It's kinda like a numbers matching eng. There are only a few know Bill Fricks Studillacs maybe 3 or 4 I have one of them and really don't want to change the engine However while doing the rebuild if I can get 20 or 30 more horsepower without changing the cu.in. and cam This is what I am trying to do
     
  6. 73RR
    Joined: Jan 29, 2007
    Posts: 5,060

    73RR
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    Basic rules of hot-rod engine building is that if you want more hp then you need to raise the compression and/or change the cam grind and if you are keeping the somewhat-low oem compression then your cam profile choices will be limited.


    .
     
  7. Isn't there an increase in compression ratio over the two years from 8.25:1 - 9:1 that accounts for the hp increase?
     
  8. 73RR
    Joined: Jan 29, 2007
    Posts: 5,060

    73RR
    Member

    As Speedy notes, the oem c/r jumps from 54 to 55, and thus the 20 hp difference. As someone mentioned, more compression means more hp......

    Carbs do not change hp, they do change how the hp is used and what you 'feel' in the throttle...good or bad.

    .
     
  9. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,585

    HEATHEN
    Member
    from SIDNEY, NY

    I know that Eldorados had them in '55-'56-'57; in '58, they went with tripower.
     
  10. '54Caddy
    Joined: Sep 11, 2009
    Posts: 758

    '54Caddy
    Member

    Speedy Canuck is right. They did boost the comp ratio from 8.25:1 in 1954 up to 9:1 in 1955
     
  11. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
    Member

    KO Thank you all for your help and I'm learning things here. I am aware the 55 has more c/r than the 54. And I learned c/r makes HP So how what gives the extra c/r to the 55?
     
  12. hoop98
    Joined: Jan 23, 2013
    Posts: 1,368

    hoop98
    Member
    from Texas

  13. I believe its different from 55 onwards due to the loss of the built in bell housing.
     
  14. Well I know it doesn't have the in built bell housing, I believe most parts are still interchangeable as the main block is the same.
    I seem to remember that post 55 flywheels are the same (manual anyway) - I guess it could have something to do with balance...
    I know my NOS shciefer flywheel was only listed for 331 to 54.


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  15. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,586

    Dale Fairfax
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    According to Motor's Manual, this would appear to be the correct if not the toal answer. Compression was bumped but they also raised the R.P.M. for rated H.P. from 4400 to 4600. Suggests a slight cam change as well???
    (Havent done the torque to H.P. calc but I don't think a simple raise in R.P.M. will result in that much H.P. difference.)



     
  16. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
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    OK So how do I get mt 54 eng. to the 55 specs The cam is the same and i think the carb is also (wcfb) could it be the head on the 55 is milled?
     
  17. Believe the 54/55 heads are the same, probably higher CR pistons. Why not just rebuild it with a better cam, the 54 heads and 3x2 - that would give you a nice bump over the 55 spec


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  18. hoop98
    Joined: Jan 23, 2013
    Posts: 1,368

    hoop98
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    from Texas

    The changes are documented here; 1955 Cadillac

    Over view on page 93
    1.65 Rockers, new Carb, New intake, new combustion chambers, dual exhaust, changed lobe centers, 3/4 point more compression.

    Specs are about 2/3 down.
     
  19. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
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    I don't get it The manual stats are the same I guess the heads are milled so the combustion chamber is smaller? causing a higher c/r.
     
  20. d2_willys
    Joined: Sep 8, 2007
    Posts: 3,458

    d2_willys
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    from Kansas

    In a 1956 Hot Rod magazine, an article on the 56 Cadillac 365 mentioned that in 55 Cadillac had redesigned the heads for better breathing and performance. They called them TURBULENT WEDGE heads. These heads were then used on 365 and 390 engines.
     
  21. studillac tom
    Joined: Apr 20, 2011
    Posts: 12

    studillac tom
    Member

    O K I still need to know what I have to do to my 54 331 caddy eng to make it a 55 with 250 hp Are the heads the same?
     
  22. hoop98
    Joined: Jan 23, 2013
    Posts: 1,368

    hoop98
    Member
    from Texas

    The heads, cam timing, rocker ratio/valve lift, compression, and carb were changed

    The heads are NOT the same.,

    [​IMG]
     
  23. vetteson
    Joined: Oct 7, 2010
    Posts: 37

    vetteson
    Member

    In 55 Cadillac raised the height of the pistons to increase the C/R. However, the cam was retarded somewhat to avoid detonation. The cam was otherwise unchanged from previous years. Actually, all Caddy cam's had the same lift and duration from '49 to '62. The '55 heads have a slightly redesigned combustion chamber, but the volume is the same as previous years and all 331 heads will interchange. Also in '55 they increased the rocker arm ratio to achieve more lift with the stock cam. Thus the increase in hp from '54 to '55 was accomplished by raising the C/R and adding more lift to the cam. The increase of hp from '53 to '54 was a numbers game, they simply increased the rpm a bit. The '55 Caddy block was the first to have a flat rear (no sub-housing) and the last to have a pilot bearing provision. If you want to make your '54 develop '55 power, mill the heads about .030 and get '55 rockers. You'll probably need '55 push rods (or adjustable studde's).

    I'd like to find an authentic Bill Frick Studillac.
     
  24. Hyfire
    Joined: Jun 18, 2004
    Posts: 1,172

    Hyfire
    ALLIANCE MEMBER

    I'd take year to year HP gains with a grain of salt. While they typically would bump HP with small revisions.... Cadillac employees are on record saying they had under rated numbers to start with in order to show larger HP increases year to year.

    Obviously things like increases in compression ratio and cubic inches are big worthwhile changes. Pick a year that has those.
     
  25. HEATHEN
    Joined: Nov 22, 2005
    Posts: 7,585

    HEATHEN
    Member
    from SIDNEY, NY

    What he says......and the same goes for factory CR ratings. The old 327s that were rated at 10.5:1 were really more like 9.7-9.8:1.
     

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