New 336° cam from BMW

Discussion in 'Airheads' started by RGregor, Dec 24, 2012.

  1. RGregor

    RGregor Been here awhile

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    According to MS the lobes of the right hand cylinders are ground without taper.
    Read the original thread (link in the first post).
    #21
  2. supershaft

    supershaft because I can

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    yes
    #22
  3. chasbmw

    chasbmw Long timer

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    Given that Moorespeed does this for a living, his reputation is very important to the long term success of his business, this is why his is unlikely to risk his rep by making claims that cannot be supported. In the Internet world, reputations can be easily shredded
    #23
  4. Rob Farmer

    Rob Farmer Long timer

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    I'm probably showing my ignoroance of cam design here but since the cam followers are off set from the centre of the cams wouldn't the followers spin anyway? I'm not sure why you'd need a taper on the cam face. I've just had a look on three used cams I have laying about and all three have a larger worn contact area marked on the exhaust valves than the inlets but all four lobes on all of them have wear marks supporting the cam followers spinning.
    #24
  5. Rob Farmer

    Rob Farmer Long timer

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    I trust Richie completely, we've had many long conversations on the phone as well as him carrying out head work for me. The quality of his work is superb.On top of that, out of all the tuners available to them, BMW choose Richie to tune their airhead powered race car, that says a lot on it's own.
    #25
  6. moorespeed

    moorespeed Adventurer

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    Thanks Rob, the follower will only spin if the cam has an angle on it and the follower has a big radius approx half a meter to one meter. then they will spin and you can see that with the ware pattern over the lobe, it is sort of S shaped. as for S/S and me making it up, when he has a little more knowlege on cams, and remember he has no idea what compression ratio he is runing,always a sign of a good engine builder, and he can find over 120 hp out of an airhead I will have a debate with him, up until that point I sugest he crawls back under his stone.
    #26
  7. jbcaddy

    jbcaddy Long timer

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    I sure wish all the personal attacks and name calling would stop :deal
    #27
  8. Voltaire

    Voltaire Bored Of The Rings

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    I've been reading this thread as my R90 racebike has a copy of the 336 cam made by a local reputable cam company.
    It goes well for a bike with a motor that cost $250 that although has been pulled apart, new rings/bearings fitted, guides relined and a few minor mods is still running the original 1973 pistons and valves..... had a good season on it, 20 odd races and only one DNF.
    I don't know what power it turns out or what the compression ratio is .....hey SS is there any room under your rock.....:rofl

    I did a build thread on it ..... http://advrider.com/forums/showthread.php?t=790873
    #28
  9. supershaft

    supershaft because I can

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    +1!
    #29
  10. chasbmw

    chasbmw Long timer

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    This is what started it. "just about everything Moorespeed has said about the 336 newly produced or otherwise sounded like he made it up to me based on my experience with them and other inmates experience with them as well. Can't see why .........
    #30
  11. supershaft

    supershaft because I can

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    At least we are in good company. I called a German piston manufacturer direct once to find out what CR one of their pistons was since they were advertising the same piston having the same CR for two differently shaped combustion chambers. On the phone in perfect English they told me they were guessing the CR since they didn't have the wherewithall to actually measure all the different models. I have told this story many times over but now is a good time to tell it again.

    It seems a lot of us need to get more cam knowledge since everyone I mentioned and then some are all getting very different results from a 336 than what Moorespeed reports. It would be great if what he reports added up with what we have experienced but . . . .
    #31
  12. supershaft

    supershaft because I can

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    That isn't personal other than mentioning sources. That comment is about what Moorespeed said he experienced with 336 CAMS versus what some of us here have said we experienced with 336 CAMS and a direct response to a comment RG made.
    #32
  13. mattcfish

    mattcfish R90X

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    Yeah, that's what I thought, offset lifters create spin, that's why they're offset....right? Same with the rocker on the top of the valve. You want it a little offset to make the valve spin.

    I think my cam had the "butterfly". looked like a stock 308 except for the 247, 336 stamped on the nose and the square pump drive. I'm using the later style cam made for bean cans.
    #33
  14. supershaft

    supershaft because I can

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    Apparently they need a little help since all those cams Rob was looking at have a slightly higher on one side cam lobe? So far every cam I have looked at does. Whatever works.
    #34
  15. mattcfish

    mattcfish R90X

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    Any way to tell on an assembled motor? Will the pushrods spin? Put my cam in over 2 years ago. The used 336 had at least 30,000 on it.
    Probably a good one I would imagine. The bearing was completely warn out and had to be replaced. I'm guessing it was at least 10 years old. The ware paterns on the lobes were all the same.
    #35
  16. supershaft

    supershaft because I can

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    Monitor valve lash. That's how I caught a lifter wearing into my 308. I think the push rods do spin.
    #36
  17. RGregor

    RGregor Been here awhile

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    Yes they do. The lifters rotate and the rods, too.

    But I believe they will always do, even with no taper.
    I had used a regrind cam once, it had no taper but, the lifters had been spinning. You could clearly see this on the side (the tube) of the lifters.

    Combining convex lifters with a cam with no taper IMHO will result in a point-wise (not line-wise) contact between lifter and cam and thus too much stress for the material.

    Tomorrow I'll measure the 336.
    #37
  18. mattcfish

    mattcfish R90X

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    Oh, so the lifters are tapered? Always thought they were flat. Now everything makes since.
    #38
  19. bmwrench

    bmwrench Long timer

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    The lifter faces have a very mild radius to ensure rotation. You can monitor rotation of the pushrods by drawing a line on the pushrods and runnng the motor with the valve cover off. It's kind of fun to watch, and you also get to watch the the oil delivery.
    #39
  20. Bill Harris

    Bill Harris Confirmed Curmudgeon

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    I don't know for sure, but I've always assumed that the "wavy", "undulating" contact pattern on the cam lobe is a sign that the lobe has the proper taper ground on it and that the lifter is rotating. (???) And is visible when the oil pan is removed.

    Or so it was explained to me many years ago. Am I correct?

    --Bill
    #40