Adjustable cam gear
  • Help
Results 1 to 9 of 9
  1. #1
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default Adjustable cam gear

    This is the Cat Cams adjustable cam gear for an 8v douvrin motor.
    Its pretty sexy, and far too nice to hide under a cover.



    I'm getting a bit ahead of myself here but have started thinking about the challenges I might find ahead of me.
    I'm not worried about dialing in the cam the first time and locking it down. I'm pondering the bits that come after that.

    Advertisement



    All the timing information for the ecu gets generated on the other end of the cam.
    I was planning ahead when I gutted the dizzy and built my sensors, as the sensor locations relative to rotation are infinitely variable within the housing, and the whole dizzy housing can rotate too, giving global adjustment once the sensors are locked down.
    With a bit of luck, I should be able to effect a change on the cam gear and recalibrate the dizzy back to the the flywheel with a timing light.
    On that note, I'm going to need to make up a more accurate pointer on the flywheel.


    Once it is timed to OE spec and locked down, marking it somehow would be good.
    Can anyone offer any advice how to mark it up??
    The blue middle is anodised alloy, and the outer gear is .....steel? ...has a bit of surface rust.
    I'm guessing its going to be easier to mark the alloy rather than the steel, but how do I mark it accurately??
    Would it be good to set it up in a mill and use some type of stylus to mark it and achieve angular accuracy using the degree counter on the mill bed???

    Or is there a heaps easier way, like buying/making a vinyl self adhesive protractor of the right size and sticking it onto the front face of the cam gear and gluing a needle onto the outer ring.

    Jo

  2. #2
    VIP Sponsor
    Join Date
    Aug 2000
    Posts
    9,548

    Default

    Quote Originally Posted by jo proffi View Post
    This is the Cat Cams adjustable cam gear for an 8v douvrin motor.
    Its pretty sexy, and far too nice to hide under a cover.



    I'm getting a bit ahead of myself here but have started thinking about the challenges I might find ahead of me.
    I'm not worried about dialing in the cam the first time and locking it down. I'm pondering the bits that come after that.


    All the timing information for the ecu gets generated on the other end of the cam.
    I was planning ahead when I gutted the dizzy and built my sensors, as the sensor locations relative to rotation are infinitely variable within the housing, and the whole dizzy housing can rotate too, giving global adjustment once the sensors are locked down.
    With a bit of luck, I should be able to effect a change on the cam gear and recalibrate the dizzy back to the the flywheel with a timing light.
    On that note, I'm going to need to make up a more accurate pointer on the flywheel.


    Once it is timed to OE spec and locked down, marking it somehow would be good.
    Can anyone offer any advice how to mark it up??
    The blue middle is anodised alloy, and the outer gear is .....steel? ...has a bit of surface rust.
    I'm guessing its going to be easier to mark the alloy rather than the steel, but how do I mark it accurately??
    Would it be good to set it up in a mill and use some type of stylus to mark it and achieve angular accuracy using the degree counter on the mill bed???

    Or is there a heaps easier way, like buying/making a vinyl self adhesive protractor of the right size and sticking it onto the front face of the cam gear and gluing a needle onto the outer ring.

    Jo
    What cam are you using?
    I'm looking for something better when I build a good motor from scratch.

  3. #3
    1000+ Posts Fordman's Avatar
    Join Date
    May 2004
    Location
    Perth/West Australia
    Posts
    1,549

    Default

    I can't see the picture on this computer (the old red cross thing), but if it is the sprocket with multiple pin holes to allow vernier adjustment by one degree each hole, I would be inclined to mark the final decision pin hole with a white paint pen after all your checks are completed. I guess that if the same pin/hole combination is used later then the alignment is still exactly correct. If the two parts of the sprocket can be assembled in any of the four main bolt holes, then a paint mark on both parts at one point would ensure same location next time. But the pin hole is the accurate marker IMO.

    A permanent mark (eg, engraving) may not be correct the next time if chain is worn or through head surface machining, and you may want to erase the mark.

    2004 Scenic I 2.0 auto (Hers)
    2016 Ford Territory (His)
    2004 WRX (Sunday car)

  4. #4
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default

    Quote Originally Posted by GRAHAM WALLIS View Post
    What cam are you using?
    I'm looking for something better when I build a good motor from scratch.
    For now, a standard R21 cam.

    Fordman, you have described the function of the cam wheel well.

    I still have not got my head around how that 'hole method' works.




    Jo

  5. #5
    1000+ Posts Fordman's Avatar
    Join Date
    May 2004
    Location
    Perth/West Australia
    Posts
    1,549

    Default

    Quote Originally Posted by jo proffi View Post
    I still have not got my head around how that 'hole method' works.
    Jo
    My way of thinking is you only need vernier (fine) adjustment for a half a tooth each way - and thats about the adjustment they have on the sprocket (10 degrees?). If it was a 36 tooth gear then each tooth is 10 degrees so thats all you need before you just use the next tooth.
    I believe you are probably using this just to get the OE timing exactly correct? Because it does just look wrong when you line up the OE timing marks but you are a half a tooth out, and nothing you can do about it. The wheel you have will allow this to be spot-on.
    I reckon the instructions will show maybe a central pin hole to begin with, then using a degree plate on the crankshaft you would set up the cam as close as possible at this setting, using dial gauge on valve or rocker or cam lobe. Noting the number of degrees out at this point, then loosening off the 4 bolts and selecting another pin hole as directed by the instructions for that number of degrees correction, then nip up the 4 bolts and recheck the timing until you get it correct. Remembering that for 2 degrees crank movement only 1 degree cam movement.
    I cant myself see why they have 4 sets of vernier pin holes, but the instructions should cover that (I would hope). But I guess there must be at least 10 combinations of pin holes to get one degree increments. Have you just sat down and played with the adjustments to see how it works?

    Last edited by Fordman; 7th July 2012 at 06:13 PM.
    2004 Scenic I 2.0 auto (Hers)
    2016 Ford Territory (His)
    2004 WRX (Sunday car)

  6. #6
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default

    Quote Originally Posted by Fordman View Post
    ... Have you just sat down and played with the adjustments to see how it works?

    Not yet, but now that I have some instructions (yours) I will later tonight.
    I could not find any instructions on the web, so your set is probably as good as it gets for me.

    The mate who gave me this cam gear just set his up and reports that an almost imperceivable movement in the cam translated to about 2 degrees crank.

    I guess looking at a 7.2mm circumference protractor, one degree is a rather small distance.


    Jo

  7. #7
    1000+ Posts Fordman's Avatar
    Join Date
    May 2004
    Location
    Perth/West Australia
    Posts
    1,549

    Default

    I notice that Cat Cam call it the Nonius method of adjustment - good word - I thought I would look it up:

    "Nonius
    , is a name also erroneously given to the method of graduation now generally used in the division of the scales of various instruments, and which should be called Vernier, from its real inventor."

    Non-helpful, but interesting!

    Although, come to think of it - the true nonius definiton was something about a sytem of ever decreasing diameters, and that may be exactly how these gears are drilled to gain a micro change in angle relationship. Ie, if you measure the radius from the centre of the wheel to each pin hole it is probably just that small amount less for each set of holes.

    More food for thought.

    I think, in the absence of instructions, that you will find a pattern between the sets of holes to find your 1 degree increments, it won't just be random. For a start, some picture I have seen of Cat Cam gears, there is one pin hole by itself - my guess this would be the starting point - and there would be an equal number of adjustments each way by 1 degree increments.
    2004 Scenic I 2.0 auto (Hers)
    2016 Ford Territory (His)
    2004 WRX (Sunday car)

  8. #8
    1000+ Posts
    Join Date
    Nov 2010
    Location
    Newcastle
    Posts
    2,878

    Default Adjustable pulley

    Hi JO,
    Your link or attatchment did not appear on the AF thread when I looked.
    Here are some quotes from Cat Cams site. Current items of course.
    “Cat Cams adjustable pulleys are made of top quality 7075 aluminum. In addition, the outer wheel is hard anodised for wear resistance.”
    From list of available items;
    RENAULT CTRE008 R20 / R25 4 cyl- 8v Mot.J6,J7. sohc rp. 42 / circular. 126,00mm. 24,00mm
    Meaning; 42 tooth sprocket, 126mm OD, belt 24 wide, round teeth.


    From another suppliers site;
    "Cat Cam’s True Lock adjustable cam pulleys offer a number of advantages over the traditional ‘vernier’ style items offered by rival companies. Primarily they are vastly more user friendly and accurate than traditional vernier pulleys. That’s because while rival designs rely on a sliding vernier scale to indicate how much cam advance or retard has been dialled in, the True Lock pulleys use a unique, fool proof and considerably easier ‘pin and hole’ system.
    The system is simple in operation – around the face of the True Lock pulley is a series of drilled holes representing one degree of cam advance or retard. Users simply have to undo the securing bolts, then rotate the two parts of the pulley until the supplied alignment pin slides into the desired hole. The pulley is then bolted back together, the locking pin is removed and the user can be confident that the cam timing is set accurately, without the need to align hard to see vernier scales. And with plus or minus ten degrees of advance and retard available, there is plenty of scope for serious adjustment."


    My suggestion of how they adjust; I think that the single hole is the standard position as shown with the bots in the center of their slots. If you move the outer part, retarding it, to the right 1 deg, the first hole around to the right will line up with an inner one. Move it 2deg and the second hole will line up etc etc. There are 10 holes in two groups to give the 10 degs. The same but opposite applies if you go the other way to the left, the cam is advanced.


    So only one hole lines up at any position from -10deg to +10 deg. 21 holes.
    Cheers Jaahn

  9. #9
    1000+ Posts jo proffi's Avatar
    Join Date
    May 2003
    Location
    sydney
    Posts
    8,496

    Default

    Thanks Fordman and Jaahn.

    You have both given me a great deal of clarity, and saved me a heck of a lot of work.

    By the sounds of things, Fordman has nailed it in his first post regarding marking up the wheel.
    Paint a spot for 0 degrees, and maybe a felt tip pen to label the holes just to make it easier for Ron.
    Nothing permanent, and re calibrate the spot each time a new cam-crank distance is used.

    Easy peasy. One spot of paint is within my skill set.

    Here is the hole in the cam cover , with a hole cut for the new gear
    I can already see murphy hiding behind the centre bit, and he'll make sure every adjuster hole needed is the one under the cover.

    Jo
    Attached Thumbnails Attached Thumbnails Adjustable cam gear-cam-cover.jpg  
    Last edited by jo proffi; 8th July 2012 at 01:51 AM.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •