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Timming problems 1.4 8v Roller rocker

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  • Timming problems 1.4 8v Roller rocker

    Looking for some advice jst recenlt started rebuilding my engine in a 1.4 rally car, I have been tryin to time my engine using a guide that i found on Burtons website

    http://www.burtonpower.com/technical...ng_timing.aspx

    I havent had any problems finding the exact TDC using my dial gauge its when i come to set the cam at 108 degrees after TDC. I use the dial gauge to find the exact point where the inlet lobe on cylinder one is at its maximum lift. At this point i then turn the crank clockwise 108 after TDC using the timeing disc on the crank at this point i then fit the timing belt and adjust the pulley so that the cam is at max lift when the crank is 1 108 degrees after TDC. I then set the valve clearnced as noted in the spec and attempt to turn the engine about 3/4 of the way round there is conact between the valves and pistons and i cant seem to understand why?? I have tried timing it a few time and them same thing happens.
    One thing am not sure about what side of the engine is cylinder 1 gearbox or timing side if im taking the reading for the lobe at the wrong side then it will b completly wrong!! (im using the timimg side t the moment)

    I need help dose anyone have any advice or a better guide please contact me Thanks

  • #2
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    • #3
      Cylinder one is the gearbox end. You're better off setting up the cam with lift at top dead centre, check the cam specs on the manufacturers website - they should give you those details.

      what cam are you using?

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      • #4
        Newman cam

        Its a Newman cam with a 280° duration, I got the cam from Andy at Hi flow Heads he told me it was a rally/sprint cam.

        If cly 1 is at the gearbox side then dose this mean that when am looking for maximum lift on the cam it will be on the inlet lobe of this cylinder.

        Could you explain what you mean by setting the cam at TDC? (Sorry bit slow )

        Thanks

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        • #5
          I had a ago at timing my engine have try my best to describe how i went about it, i anybody in the know has a spare five minis to have a look and let me know what they think. Thanks

          Firstly found the exact TDC using a dial gauge and timing disc.

          Then fitted camshaft and roller rocker arms, set my dial gauge on inlet arm No 1 (gearbox side) rotated to camshaft until the dial gauge reached dwell period where the valve is full open. I then turned the crank 109° after TDC (clockwise) at this point I refitted the cam belt ensuring that the cam did not move. I then turned the engine until the rocker arm was 0.2mm after max lift, and noted the reading on the timing disc I repeated this process 0.2mm before max lift and noted the reading. By adding the two readings together and dividing by 2 I then had a reading to set the timing disc to on the crank at this point the cam would be at maximum lift. At this point I marked the cam on the gearbox side using a pencil so that when the cam belt was removed I still had an accurate mark where that cam was at max lift. I then removed the cam belt set the cam as close to the pencil mark as possible without putting any pressure on any of the valve springs ( Which was causing the cam to jump when the belt was removed) I then set the crank to 109° after TDC and refitted the cam belt using a flat bar on the end of the cam to move it against the springs until it was as close to the mark as possible. (This was very hard) After setting the cam belt to the nearest tooth I slacked the veriner pulley off and without moving the crank turned the cam shaft until it lined up with the pencil mark, tightened the pulley.

          Set valve clearances to 0.2mm of the inlet and 0.25mm on the exhaust.

          Engine timed, I think :-%

          When the engine is at 109° after TDC the rocker arm on CYL 1 (Gearbox side) is at max lift (Valve fully open)


          After timing the engine I removed the head and placed play dough on the top of piston 1 rebuilt the engine and set the timing exactly as I had it at before, turned the engine over once and removed the head. The indents on the dough showed there is approx 1mm clearance on the inlet and 1.5mm on the exhaust so I’m guessing might need to remove a small notch from the piston to allow me to rev that wee bit higher.

          What you think bad, good, terrible?

          Also can any one tell me the what size of bearing head is on a 1999 Quiksilver

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          • #6
            Thats quite an elaborate method lol.

            If you know what the lift should be at TDC you can quite simply use a DTI to set the inlet valve lift on cyl 1 to that figure whilst the bottom end is at TDC and then put the belt on. This is the most accurate method of setting the cam timing. I tend to loosen off the vernier pulley when i put the belt on as it makes it less likely to move the cam and ensures the belt is tensioned correctly, then after the tensioner is tight you can tighten up the vernier pulley again.

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            • #7
              Sounds like i good method, Pity my cam isn’t stamped and did mot come with a grate data sheet. I was told is was a one off cam from Newman similar to a ph4 rally/sprint cam. I only have readings from max lift, camshaft degree at TDC and valve clearances very poor. Hence the elaborate method of timing my engine! Do you think my method ok though?? Thanks

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              • #8
                PH4's can be tight on piston to valve clearance, so chances are it's not a million miles off... I was advised to try and keep a minimum of 1.6mm clearance so you will need some small cutouts.

                Basically as long as you're confident nothing it going to touch and the engine runs ok I wouldnt worry too much because the cam timing can be optimised on a rolling road later. Just make sure you make your cutouts a little deeper than they need to be so you can advance it a bit more later if need be. Make a mark on the pulley where maximum advance is during a dry build to save you time later.

                You can use a light spring in place of a valve spring to measure the valve to piston clearance as well... just push down on top of the valve and watch the DTI... no need to use play-doh ;-)

                Oh and by the way this is all stuff I've learnt from the forum - It's all there if you search a little for it!

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