Mi16 Cam Timing and Vernier Pulleys
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  1. #1
    1000+ Posts PeterT's Avatar
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    Default Mi16 Cam Timing and Vernier Pulleys

    WRX2PUG recently had dramas finding this info, so we thought it might be usefull to post it here for future reference.

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    When vernier pulleys are fitted to an Mi16, the reference(s) are lost for locking the pulleys to the cylinder head, in order to fit a cam belt and time the engine correctly. Normally a dowel locks each pulley with the head, and a third dowel locks the crank with the block. It's very hard to get the standard cam timing wrong if the dowels are used.

    To further complicate matters, the Mi16 engine has no external timing marks. So to proceed further, TDC needs to found accurately, then marked on the harmonic balancer, or the flywheel, if you wish to change to verniers. Beware that the inner and outer of the balancer can move.

    Once TDC is established, the easiest way to set the cam timing is with a dial indicator, measuring the valve lift at TDC. These are the std. values:

    XU9J4: #2 inlet pulley - 0.033" @ TDC
    XU9J4Z: #3 inlet pulley - 0.045" @ TDC
    XU9J4 (and Z): #2 exhaust pulley - 0.033" @ TDC

    You can see from the above values that the inlet and exhaust on the XU9J4 have equal lift at TDC, whilst the XU9J4Z has the inlet advanced a tad, to help compensate for its lower CR. The std. cam timing is in fact very mild:

    XU9J4:
    inlet duration 214 deg. @ 0.050"
    lift 0.360" 114 deg ATDC

    exhaust duration 214 deg. @ 0.050"
    lift 0.360" 114 deg BTDC

    XU9J4Z
    inlet duration 214 deg. @ 0.050"
    lift 0.360" 111 deg ATDC (difference due to #3 pulley)

    The best std. performance from the XU9J4Z can be found by advancing the inlet cam timing a tad further. The easiest way to do this is with an offset key. Owen Wuillemin sells them for $30 from memory. If you want more performance after that, a bigger inlet cam is needed.
    Last edited by PeterT; 14th October 2004 at 05:41 PM.

    '92 205 Mi16
    '90 Mi16x4

  2. #2
    Fellow Frogger! Kyle's Avatar
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    Very useful information there peter

    So where can I take my s16 to in sydney to get this work done and supply the nessecary parts?

  3. #3
    1000+ Posts brenno's Avatar
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    Try Paul Vassallo at Gladesville Prestige Cars. He has just fitted Peter's cam to my BX.

    You can call him on 98172134.

  4. #4
    Fellow Frogger! Kyle's Avatar
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    Tx Macquered! So do they do much work to pugs or not generally?

  5. #5
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by Kyle
    Very useful information there peter

    So where can I take my s16 to in sydney to get this work done and supply the nessecary parts?

    I can supply a Stage I cam if required. You won't need verniers with that.
    Last edited by PeterT; 14th October 2004 at 05:36 PM.

    '92 205 Mi16
    '90 Mi16x4

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    1000+ Posts brenno's Avatar
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    Paul specialises in Peugeots, so he should be able to set you straight.

  7. #7
    Fellow Frogger! Kyle's Avatar
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    I'd like to learn more about this peter, like prices and stuff.

    What sort of performance gains can be had?

  8. #8
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by jester_fu
    Peter, does my memory serve me correctly in saying the Harmonic Balancer dowl position is center stroke, and not TDC?
    That's correct. The dowel locks the pistons half way up, half way down, so there's no chance of hitting a valve while you change the belt.

    I charge $250 exchange for the Stage I cam grind. It still has a smooth idle, works with all std. engine parts and ECU. Maximum hp increase is approx. 15%.

    I sold one recently to DooshDoosh for his S16 but I haven't had any feedback.
    Last edited by PeterT; 14th October 2004 at 05:46 PM.

    '92 205 Mi16
    '90 Mi16x4

  9. #9
    1000+ Posts cam85's Avatar
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    Peter.

    With the higher compression MI16 motor. Will the stage 1 cam you do still have the 15% increase. Is there anything you know of to produce more power with the Higher CR engine. Is it the regrind that owen has on his race car the best way to go. Do you know the specs of it. Also is there anything you can do to the exhaust cam to gain more. Also Head work??

    Cam
    98 Xantia CT
    94 205 Gti Classic #9
    92 405 Mi16
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    http://www.aussiefrogs.com/forum/res...-race-car.html

  10. #10
    Fellow Frogger! KRISKARRERA's Avatar
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    Quote Originally Posted by PeterT
    The best std. performance from the XU9J4Z can be found by advancing the inlet cam timing a tad further. The easiest way to do this is with an offset key. Owen Wuillemin sells them for $30 from memory. If you want more performance after that, a bigger inlet cam is needed.
    Any benefit to doing this to the XU9J4 then?
    405 MI16
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    Le lion va de la force la force!

  11. #11
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by KRISKARRERA
    Any benefit to doing this to the XU9J4 then?

    Yes. It achieves the same end result as fitting verniers, at a fraction of the cost

    Cam,
    I haven't dynoed a 160hp engine yet with the cam, but I'd imagine it would see a similar increase. Owen has the Stage II grind. One of the secrets to the success is leaving the std. exhaust cam in place. The exhaust port is very efficient and thus doesn't need to be altered for a Stage I or II cam. The exhaust needs to flow approx. 80% of the inlet. If the cams are the same, this figure is over 100% some of the time. ie over exhausting. As for head work, just a good 3 angle grind will yeild the best.

    '92 205 Mi16
    '90 Mi16x4

  12. #12
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    "The easiest way to do this is with an offset key. Owen Wuillemin sells them for $30 from memory."
    What's an offset key? And how many degrees does that advance the cam if u know?
    405 MI16
    170bhp
    Le lion va de la force la force!

  13. #13
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by KRISKARRERA
    "The easiest way to do this is with an offset key. Owen Wuillemin sells them for $30 from memory."
    What's an offset key? And how many degrees does that advance the cam if u know?
    A woodruff key is used to locate the cam pulley with the camshaft. It doesn't actually transmit power, this is done by the bolt and larger flat washer. An offset woodruff key is "stepped". You can only step so far until the key is severly weakened. The keys that Owen sells advance the inlet cam 4 crank degrees.

    '92 205 Mi16
    '90 Mi16x4

  14. #14
    Fellow Frogger! KRISKARRERA's Avatar
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    I was gonna say just move the inlet pulley by one tooth but I suppose that puts the timing out for the dizzy cap??
    In fact, if u move the inlet cam how the hell do u retain the same timing for the dizzy cap on the mi16?
    Last edited by KRISKARRERA; 17th October 2004 at 02:04 AM.
    405 MI16
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    Le lion va de la force la force!

  15. #15
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by KRISKARRERA
    I was gonna say just move the inlet pulley by one tooth but I suppose that puts the timing out for the dizzy cap??
    In fact, if u move the inlet cam how the hell do u retain the same timing for the dizzy cap on the mi16?
    One tooth is approx. 16 degrees. I personally haven't tried it, but I'd say it would be just about disaster.

    Moving the high tension a few degrees won't effect the ignition timing. If the Mi16 had low tension via points, reluctor, hall effect, etc. in the distributor, then yes, you'd have to re-time the ignition.

    '92 205 Mi16
    '90 Mi16x4

  16. #16
    Fellow Frogger! KRISKARRERA's Avatar
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    Crikey 16 degrees, didn't realise it was that much!

    Am I correct in saying that by advancing the cam slightly it closes the inlet valves slightly before normal and seeing as this happens after bottom dead centre you get less air shooting back pass the closing valve, especially at low revs?
    I also wonder if the makes the torque peak at lower revs.
    Last edited by KRISKARRERA; 18th October 2004 at 01:44 AM.
    405 MI16
    170bhp
    Le lion va de la force la force!

  17. #17
    1000+ Posts PeterT's Avatar
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    The compression stroke doesn't start until the inlet valve closes. So closing the inlet valve earlier (by advancing the inlet) gives a longer compression stroke. This increases the cylinder pressure increasing low end torque (at the expense of top end power).

    '92 205 Mi16
    '90 Mi16x4

  18. #18
    Fellow Frogger! KRISKARRERA's Avatar
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    Any idea what kind of changes a 4 degree advance would make? How much further down will torque peak? 500rpm? 50? lol. A before and after rolling road graph would be good.
    405 MI16
    170bhp
    Le lion va de la force la force!

  19. #19
    Member DanS16's Avatar
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    Peter,

    Regarding the Stage 1 cam for an S16, you say you'd expext and 15% increase in power, is this generally at the top end?
    i.e: If fitted, is it still possible to return good fuel economy providing revs are kept below 3500rpm? Im getting about 8.8L/100km at the moment, would you expect this to drop off drastically? (assuming same driving stylye before after)
    Be nice to have some more power on top for when required , but not at the cost of reduced economy during 'normal' driving conditions.

    Cheers.
    C4 Hdi - Pierre, Suby BRZ - Fuji and Wren the FRB Clio IV

  20. #20
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by KRISKARRERA
    Any idea what kind of changes a 4 degree advance would make? How much further down will torque peak? 500rpm? 50? lol. A before and after rolling road graph would be good.

    about 300rpm.

    DanS16,
    the 15% was measured on a 1.9L Mi16, so I couldn't quote numbers for a 2.0L. Ask DooshDoosh. He's just put one in his S16. At cruise, fuel economy will be the same, as the O2 sensor will control that. If you start to use the extra hp, you'll naturally use more fuel.

    Here's a URL of the dyno figures for the 1.9L.

    http://www.users.bigpond.net.au/tayl...cam_change.htm

    '92 205 Mi16
    '90 Mi16x4

  21. #21
    Member DanS16's Avatar
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    Cheers Peter,

    Ill put it on the Xmas list..

    Will PM dooshDoosh for some feedback.

    I notice you said it was on an exchange basis. Im in Adelaide, so would it be a case of getting the new cam sent over, fitting it, and sending the old one back? Or do you need the old one first? (thinking of cars time off road)

    Ta.
    C4 Hdi - Pierre, Suby BRZ - Fuji and Wren the FRB Clio IV

  22. #22
    1000+ Posts PeterT's Avatar
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    Quote Originally Posted by DanS16
    Cheers Peter,

    Ill put it on the Xmas list..

    Will PM dooshDoosh for some feedback.

    I notice you said it was on an exchange basis. Im in Adelaide, so would it be a case of getting the new cam sent over, fitting it, and sending the old one back? Or do you need the old one first? (thinking of cars time off road)

    Ta.
    If it's S16 or 2L Mi16 you'll need to send me your cam as I don't have any spares. The drive for the vacuum pump is different to the distributor drive on the 1.9L cams. Turn around with express post should only be 4-5 working days.

    '92 205 Mi16
    '90 Mi16x4

  23. #23
    1000+ Posts cam85's Avatar
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    How much will it cost me to get you to do the 3 angle grind on the head.

    Cam
    98 Xantia CT
    94 205 Gti Classic #9
    92 405 Mi16
    87 205 GTi Race Car
    http://www.aussiefrogs.com/forum/res...-race-car.html

  24. #24
    1000+ Posts PeterT's Avatar
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    Approx. $12/valve. That assumes you've got good guides.

    '92 205 Mi16
    '90 Mi16x4

  25. #25
    1000+ Posts cam85's Avatar
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    SO if i were to get bronze guides and the grind. all new???
    98 Xantia CT
    94 205 Gti Classic #9
    92 405 Mi16
    87 205 GTi Race Car
    http://www.aussiefrogs.com/forum/res...-race-car.html

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