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Thread: Timing a VVT cam

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    Timing a VVT cam - Solved

    I'm measuring up the stock cams on this Suzuki M16A engine, which has a hydraulic VVT unit on the intake cam. I measured the intake as opening at 2 degrees ATDC, which sounds like the full retarded position.

    Is there some trick to putting the cam in to the full advance position, so I can time it as if the VVT was fully activated? Here's a few pics:








    Last edited by Sprinkles; 16-09-17 at 06:37 PM.

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    Are you planning to run the engine without VVT or are you trying to measure piston to valve clearance at maximum cam advance?

    Those cam phasors normally have an internal pin to lock them when there is no oil pressure so they won't clatter at cranking speed. So there is no easy way to partially / fully advance the cam other than jumping teeth on the chain. The degrees per phasor tooth is (720 / number of teeth).

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    Quote Originally Posted by elfturbomax View Post
    Are you planning to run the engine without VVT or are you trying to measure piston to valve clearance at maximum cam advance?

    Those cam phasors normally have an internal pin to lock them when there is no oil pressure so they won't clatter at cranking speed. So there is no easy way to partially / fully advance the cam other than jumping teeth on the chain. The degrees per phasor tooth is (720 / number of teeth).
    Initially I'm just trying to verify the stock cam timing, and measure the piston to valve clearance at full advance, with a view to figuring out how much I can increase the lift and duration while still running the stock bottom end. Ideally I would like to add some compression as well by milling a little bit off the head, this needs to be factored into the PTV clearance as well. If I could get a fixed adjustable inlet sprocket for a reasonable price, I would delete the cam phasor, performance parts for these engines are pretty expensive.

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    Quote Originally Posted by elfturbomax View Post
    Those cam phasors normally have an internal pin to lock them when there is no oil pressure so they won't clatter at cranking speed. So there is no easy way to partially / fully advance the cam other than jumping teeth on the chain. The degrees per phasor tooth is (720 / number of teeth).
    Hey Elf, do you know if these locking pins are typically designed to be able to lock the phaser at full revs? The reason I ask is that I think I'll lock the new inlet cam in the full retard position. It's possible to get aftermarket blocks for Ford phasers that sit in the oil galleries and hold the rotor thingies in place, I would have to make these blocks for the Suzuki. If I can just use the locking pin for this function, that would simplify things.

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    I think I've got it sorted.

    Having measured the cam timing and PTV clearance with the intake cam in full retard position, I proceeded to ignore the "DO NOT DISMANTLE" embossed on the phaser, and took it apart. Here it is in the full retard position:




    On closer inspection, we can see the locking pin that Elf describes, holding it in the full retard position:




    Blow some compressed air into the oil gallery that feeds the locking pin, hey presto, phaser unlocked:



    So it should be a simple matter of jamming something behind the rotor thingy to hold the phaser in the full advanced position, and measure the PTV clearance.

    At this point I'm undecided if I lock the phaser in the full retard position, or let the ECU control it. The locking pin looks pretty delicate, so I'll add something more substantial if I do decide to lock it. Might wait to see how the new cams measure up before deciding.

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    You don't need to lock the phasor fully retarded if you are not running the variable cam control. You only need to leave the solenoid de-energised. That means oil pressure is directed to retard the cam as well as the engine mechanically retarding the cam due to its normal rotation. The locking pin is only to hold the cam at cranking speeds when there is no oil pressure and the engine is rotating slow enough that a closing lobe ramp might be able to force the cam advanced a bit (until the next opening lobe ramp forces it back retarded).

    If you find the fully advanced clearance isn't sufficient for the new cam you can always fit some small blocks in the advance side of the chambers to limit the available advance.

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    Your over thinking this whole procedure. When i checked my ptv with plasticine, i just turned the crank and had a spanner on the intake cam at the same time and pulled the cam advanced. You can even crank the motor over from the intake cam, i just sort of shared the load.

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    Quote Originally Posted by Sprinkles View Post
    I think I've got it sorted.

    Having measured the cam timing and PTV clearance with the intake cam in full retard position, I proceeded to ignore the "DO NOT DISMANTLE" embossed on the phaser, and took it apart. Here it is in the full retard position:
    You know what they say...

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    Quote Originally Posted by Mc Juicy Hairy Balls View Post
    Your over thinking this whole procedure. When i checked my ptv with plasticine, i just turned the crank and had a spanner on the intake cam at the same time and pulled the cam advanced. You can even crank the motor over from the intake cam, i just sort of shared the load.
    If I did that it would snap the locking pin in the phaser

  10. #10
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    Must be a shit pin. You took the plugs out right?

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