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3/4 cam???

Discussion in 'The Hokey Ass Message Board' started by Dan, Nov 8, 2013.

  1. Dan
    Joined: Mar 13, 2001
    Posts: 2,384

    Dan
    Member

    See this term kicked around a lot...obviously its in reference to the fact that it is a performance grind, not quite stock... i.e. "3/4 race"...
    What I don't get is, its 3/4's of what?? At what point is a cam a 1/4, 1/2, 3/4, full etc.? I am sure I am overthinking this and it was obviously just an early marketing ploy...a way for the early guys to puff up and say "Well my engine has a 3/4 race cam..." I just constantly find myself wanting to ask someone when they say they have a 3/4 cam "3/4's of what??" Any insight into the origination of this term??? Thanks-
     
  2. hendo0601
    Joined: Aug 24, 2013
    Posts: 288

    hendo0601
    Member
    from Tacoma, WA

    I too take issue with people saying "3/4 cam" because I am just not sure what the hell it is 3/4 of? I haven't heard this term get used in a few years, but most of the people I heard use it also referred to them as an RV cam. How do you quantify what 3/4 of a race cam profile is? It probably originated with the guy whos brother's uncle's sister's cousin's best friend had a "67 Dodge Challenger with that "440 Hemi" 3/4 race cam and 4.56:1 rear gears from the factory".
     
  3. I haven't heard that term since I was a teenager. Many many many years ago. Lol
     
  4. Bert Kollar
    Joined: Jan 10, 2007
    Posts: 1,232

    Bert Kollar
    Member

    I think it started in the 50's with the flatheads. Cam grinders use to sell them as street grind, 3/4 or full race
     

  5. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
    ALLIANCE MEMBER

    I had a 3/4 cam once. Ran really rough with the back two cylinders out.
     
  6. scrappybunch
    Joined: Nov 16, 2011
    Posts: 412

    scrappybunch
    Member
    from nj

    Van Idersteins speed shop here, had a 3/4 grind mounted up on the wall. Yep the 4 rear lobes were sawed off.
     
  7. Thumper
    Joined: Mar 7, 2005
    Posts: 1,610

    Thumper
    Member

    Oh geeze.....not this shit again....:rolleyes:
     
  8. BillWallace
    Joined: May 6, 2011
    Posts: 132

    BillWallace
    Member

    This is pretty simple really. After ww2 when speed parts were something you could buy from adds in magazines etc cam grinders used the term to identify cams that did not provide the lift & duration of the race grinds thus were 3/4s ( or less than) of the grind of the full race cams.
     
  9. Dan
    Joined: Mar 13, 2001
    Posts: 2,384

    Dan
    Member

    I thought I saw in the latest Speedway they had a new line of cams they were marketing as "3/4"? Sorry if this has been beat to death, I just don't remember ever seeing the topic come up...
    A cam with a 1/4 of it missing...that's funny shit right there-
     
  10. models916
    Joined: Apr 19, 2012
    Posts: 379

    models916
    Member

    Back in my days it meant 300 dur with 400 lift at the cam lobe. 3/4
     
    22rdstrguy likes this.
  11. Hdonlybob
    Joined: Feb 1, 2005
    Posts: 4,115

    Hdonlybob
    Member

    Good question. I have often wondered the same thing...
    This answer seems to make sense..
     
  12. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,564

    HEATHEN
    Member
    from SIDNEY, NY

    It was just the terminology of the day.....it was hotter than stock, but not really up to the "race" cam specs, so it was "3/4 race". I picked up a few N.O.S. Wolverine cams at a swap meet last sunday, and one of them is a solid lifter cam for Pontiac V8s with "super full race" printed on the box, so I guess that it trumps both of them!
     
  13. Dan
    Joined: Mar 13, 2001
    Posts: 2,384

    Dan
    Member

    "super full race", that's good...reminds me of "Do not taunt Super Happy Fun Ball!"

    300 duration, 400 lift would be an interesting definition as it refers to actual specs...
     
  14. If this is true, what is "full race" derived from?

    I remember "street grind", "3/4 race", and "full race", The names were just comparative names for us idiots that didn't understand all the cam spec numbers.
    A street grind was a little hotter than stock, a 3/4 cam had a lope at idle but was able to be driven on the street and a full race cam was meant for the track, not really something you would want to put up with on the street.
     
  15. The Isky Max 1 camshaft for Flathead Ford, is refered by Isky as a 3/4 race cam.
    The specs are .364 lift 249 adv. duration.
     
    Sharpone likes this.
  16. 40FordGuy
    Joined: Mar 24, 2008
    Posts: 2,907

    40FordGuy
    Member

    What 40FORDPU said.

    4TTRUK
     
  17. This term has bugged me since the 70s. I pissed off anyone saying ( what ever amount of race they said ) that by asking what kind of race is it for,road race drag off roar etc etc and then explain why they are not the same. The term was used a lot in New Zealand back in the day. JW
     
  18. HEATHEN
    Joined: Nov 22, 2005
    Posts: 8,564

    HEATHEN
    Member
    from SIDNEY, NY

    Some people couldn't even go with "3/4 race".....when I worked in a parts store in the '80s, a guy walked in one day and wanted a 3/4 INCH cam. I told him that, at .750 valve lift, he'd probably run into valve to piston clearance issues.
     
  19. A 3/4 cam has @ 270 degrees of duration or 3/4 of 360 degrees of rotation. A circle is 360 degrees. A quarter of that is 90, correct?

    It does not describe lift just duration of the cam shaft. Now here is where we stray anything in the 280+ range is considered a full race cam, obviously you cannot have your valves open for the full duration of a cam rotation.
     
  20. hendo0601
    Joined: Aug 24, 2013
    Posts: 288

    hendo0601
    Member
    from Tacoma, WA

  21. 'Mo
    Joined: Sep 26, 2007
    Posts: 7,432

    'Mo
    Member

    This is correct.

    Isky had no problem with the term.
    Note how similar his 3/4 and full-race cams are in both lift and duration.
    Sometimes it was more a matter of lobe profile (i.e., steeper ramps).

    [​IMG]

    Same for McGurk. (Also 'D.P.' cams, with in./ex. differences in both duration and lift).
    [​IMG]

    Likewise for Howard, Herbert, Spalding...This was standard terminology of the day, among the cam grinding pioneers. Old Timers still use the term.

    Incidentally, The 'D.P.' designation is for 'Dual Pattern', because the in./ex. grinds are not the same. (Old Chevy sixes made good use of additional ex. duration, without losing street-ability.)
     
    Last edited: Nov 9, 2013
  22. gkgeiger
    Joined: Nov 28, 2007
    Posts: 767

    gkgeiger
    Member

    I've never heard this term used in anything but a flathead, but at 70 I've heard it for years. I use it because that's the way my cam was advertised.
     
  23. 1971BB427
    Joined: Mar 6, 2010
    Posts: 8,720

    1971BB427
    Member
    from Oregon

    Ditto! I used to hear and read the term used in advertising a lot in the 60's. I can't say I've heard that terminology used in a couple decades or more. Never made sense to me back then, and still doesn't today.
     
  24. 1971BB427
    Joined: Mar 6, 2010
    Posts: 8,720

    1971BB427
    Member
    from Oregon

    Or maybe lobe separation? Often the shorter LSA was used on strip cams, and longer LSA was used for more streetable cams, so they idled better, and had more vacuum.
     
  25. 'Mo
    Joined: Sep 26, 2007
    Posts: 7,432

    'Mo
    Member

    BIG factor! Good point.
     
    Last edited: Nov 10, 2013
  26. s55mercury66
    Joined: Jul 6, 2009
    Posts: 4,335

    s55mercury66
    Member
    from SW Wyoming

    Athough I imagine the term dates back farther than 1956, my dad had my uncle (service manager at Ogg Ford, Glouster, Ohio) install a "3/4 cam" in his 312 in his new '56 Sunliner.
     
  27. Scumdog
    Joined: Mar 3, 2010
    Posts: 630

    Scumdog
    Member

    Yep, bored out Zody motor with Bedford pistons, 1/2 race cam, flows and tripple SU's:D

    Any of you Yanks understand this??
     
  28. colinsmithson
    Joined: Jan 27, 2013
    Posts: 383

    colinsmithson
    Member

    Us Aussie understand
     
  29. colinsmithson
    Joined: Jan 27, 2013
    Posts: 383

    colinsmithson
    Member

    A cam guy once told me you have stock and full racing 1/2 way between the 2 is 1/2 race
    And is easy parts sell to remember instead of lots of numbers most do not understand
     
  30. volvobrynk
    Joined: Jan 30, 2011
    Posts: 3,587

    volvobrynk
    Member
    from Denmark

    I'm not an American, so the things that makes sanse to you is odd to me, and odd too you is really weird me.

    We use to just list cams as: stock, fast road, rally/track (hardcore road) or full race.
    3/4 must be a rally/track, bad idleling, but gets better with more RPM. But no screamer.

    I get the "zody w/Bedford pistons 1/2 race, flows and triple su".
    And around here we would say:"that is one that really could put flaps down". :-D

    Around here, people calls a hotter cam for sharp cam.
    And we only puts up Duration/lift, in adds.
    I see on here you list other kinds of stuff. Sometimes other stuff, and even put different values for in and out lobes.
     

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