A VW 16v camshaft study.

Discussion in '16-valve' started by Toyotec, Feb 9, 2008.

  1. ben87 Forum Member

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    The thought did enter my mind, as did the exhaust cam mod, although i'm not sure how the 933 stamp would be relevant to the exhaust cam. I can't see any other markings on the cam, and i've also looked on each end where i believe Piper and Kent stamp them.

    The car made 131bhp at JKM down in Portsmouth a year or so ago and they seemed happy with it's fueling and general health, so I guess that would go against the idea of regrinds?

    I'm tempted to bung the standard cams that i have sat in the garage into the golf. I guess that way it would make it easier to analyse this "933" one....
     
  2. danster Forum Addict

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    The std base circle of the cams is 38mm, if you can check / measure this with a vernier and than check / measure the top of the lobe to the bottom of the base circle you will get the cam lift.
    It does look like the sort of mod you would get when a shop regrinds the cams.
    Post up results for both cams and we will be able to help more.:thumbup:
     
  3. Nellis Forum Member

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    It would be safe to assume they still have the std BCD of 38 as the peripheral bevelled edges on the lobe is still intact. After a regrind the bevel on the heel will be gone but the nose's bevel will be visible as most material is removed from the base. I hope this pic from a Schrick catalogue explains.

    [​IMG]
     
    Last edited by a moderator: Jan 29, 2018
  4. azur Forum Member

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    is the ABF exhaust lift at TDC of 1.1 mm a factory figure? Going to use lift at TDC as an initial method to time my cams seeing as i have bugger all timing marks to go on!
     
  5. azur Forum Member

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    anyone? closest i can get it too is 0.8mm. another tooth and it goes way over at nearly 3.0mm. 1.1 mm too me seems alot for a standard cam seeing as the catcams i have are 1.05mm...

    hmm
     
  6. danster Forum Addict

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    What cams? ABF or Catcams you refer too in above posts.
    The hydro tappets maybe compressing slightly and making it hard to get an accurate lift at tdc.

    The usual way to time aftermarket cams is at full valve lift. eg Something like 108deg of crank rotation from TDC is when full inlet valve lift should occur.
    Alternatively just set them to equal overlap at tdc then play around with the vernier till a good spot is found.
    The vag 16v is pants for this as it involves whipping cam cover off to get to inter cam chain wheels and readjusting the ignition timing with every change of the exhaust cam.
     
  7. azur Forum Member

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    im doing standard ABF exhaust with catcams inlet. The only factory timing marks i have to go on is the circle on the ABF internal gear as i seem to have a duff pulley!

    the last time i timed them i used the centerline method... but ive been reading that it isn't highly accurate due to most modern aftermarket cams having asymetrical lobes.

    Was trying the TDC method as its simpler.... but might have to bite the bullet and get a timing wheel on and use valve opening times at 1.0mm valve lift which is meant to be the most accurate.

    If i had a adjustable cam pulley i wouldn't have this problem. want to get it right first time as like you say... its a pita taking all the gubbins off each time you want to make an adjustment
     
  8. danster Forum Addict

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    Hmm. OK. That is a bit awkward for you then. As you are running the internal chain wheel vernier on the inlet cam, I presume. Could you not just line up the std cam timing belt pulley and exhaust cam chain wheel to their respective marks, then set the inlet cam using the full inlet valve lift method?
     
  9. azur Forum Member

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    the std cam timing belt pulley doesn't have the timing marks in the right place from the factory... as i didn't take it of the cam when i removed them (unscrewed a bearing cap stud instead). Thinking about it... it looks like it might have been put on back to front when new. might see if i can flip it on the keyway and see if they line up.

    the best i can do with the internal gear mark is put it at 3 o'clock as i have an adjustable one on the inlet.

    the exhaust timing needs to be done first because any change in the exhaust position will throw the inlet out.
     
  10. azur Forum Member

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    Solved!pulley keyway had sheared off in the cam recess... probably when the cambelt went.
    it must have been rotating slightly on the cam each time it was turned!
     
  11. G60Dub

    G60Dub Forum Member

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    :thumbup: Good news bud! Get your thread updated when you get a new key in there and get the cams timed back up... Watching with interest.
     
  12. azur Forum Member

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    will do! Did an impulse buy and brought an catcams true lock vernier pulley [:$] will let you know how it goes...
     
  13. ben87 Forum Member

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    Here are my results for the "933" cam:

    Base circle of 37.98mm

    Peak lift of 8.94mm

    The closest that I can see to that in this thread is the pre-94 9a at 8.8mm peak lift

    KR cams will be going in tomorrow :lol:
     
  14. danster Forum Addict

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    It could be that the cams have been checked for motorsport scrutineering purposes. Possibly to prove they were std. The 933 may be a technical scrutineer's stamp or something. Do you know where the engine or head came from?
    As Nellis pointed out though, the cam still has it's slight radius at the base of the lobe suggesting it has not been altered.
     
  15. gti16 New Member

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    Hello, I'm from Spain and I read a lot of information at this forum I am passionate about these cars. My level of English is not very good but I'll try.
    I wanted to ask why the camshaft exhaust you put 226 degrees in my technical handbook says "43BBDC - 3 BTDC", thus the 3 degrees would be subtracted leaving an opening to 1mm total of 220 and 6 degrees negative overlap . Is this correct, a salute and thank you very much everyone for sharing so much information.

    16v camshaft (Nockenwelle) for ABF, 9A and PL and KR engines.
    All Measurements at 1mm valve lift
    IVO= inlet opens
    IVC= inlet closes
    EVO= exhaust opens
    EVC= exhaust closes
    PL= peak lift.

    KR
    Inlet # 027 109 021 AH
    IVO 3 ATDC
    IVC 35 ABDC
    Duration -3 +180 +35 = 212
    PL 9.6mm

    Exhaust cams for 027/051 103 373E/NC NC =* Not classified or No letter
    Exhaust # 027 109 022 G
    EVO 43 BBDC
    EVC 3 BTDC
    Duration 43+180-3 = 220
    PL 10.2mm
     
  16. arnau Forum Member

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    hasn't anyone used two ABF exhaust cams in a kr? It looks as if it was going to be better than two kr ones...?


    edit: I forgot to mention that I was refering to ABF exhaust cams!
     
    Last edited: Aug 17, 2010
  17. Ess Three Forum Member

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    There can be only one Nellis from Sportcam in that part of the world!
    Hello again sir...how are you? [:D]
     
  18. arnau Forum Member

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    :p
     
  19. chrismc Forum Junkie

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    I have a pair of ABF cams in my KR.

    A cheap and alternative way of going for a setup akin to twin KR exhaust cams.

    Very difficult to quantify the difference without before/after rr plots
     
  20. arnau Forum Member

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    what spec is your engine? Is it all stock kr with just abf cams? If so, was the change from kr to abf cams noticeable all over the rev range, or you got only top-end gains?

    :thumbup:
     

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