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1280 grind cam problems, install strait up?

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  • 1280 grind cam problems, install strait up?

    ok things arent looking right here... the #1 is at tdc and the intake and exhaust valves arent on thier base circle....am i supposed to degree this thing or does it install straight up?
    #4 is close to tdc and has both its lobes on the base circles....as if the firing order is 456123... whats the deal?

    the marks are ligned up on the crank and cam....this isnt my first cam and def not my first 60*v6 cam install....

    or maybe its just lack of sleep
    Last edited by merlot566jka; 12-07-2007, 09:23 PM.
    3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe ALL FOR SALE (minus the car)
    96 LT4 6spd corvette. 355, AI 215cc LT4 Comp CNC Heads, Prope SRS pistons, Ported intake, ARH long tubes, Corsa Indy Pace 4:10 gears
    2012 Chevy Sonic Turbo 6spd
    1970 M35A2 Deuce and a Half, Spin on filters, Turned up IP, HIDs, Flat Black, 11.00x20 singles.

  • #2
    you sure you dont have the engine 180 off?
    94 Grand Prix
    3400- NX 75 shot, Cammotion cam, S&S headers, and a few more toys

    Comment


    • #3
      how can that be? the timing mark on the crank points towards the cam and the cams timing mark toward the crank.... i dont see how it can be 180 off if the alignment marks are in place....

      you can make a dist 180 out, but not here
      3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe ALL FOR SALE (minus the car)
      96 LT4 6spd corvette. 355, AI 215cc LT4 Comp CNC Heads, Prope SRS pistons, Ported intake, ARH long tubes, Corsa Indy Pace 4:10 gears
      2012 Chevy Sonic Turbo 6spd
      1970 M35A2 Deuce and a Half, Spin on filters, Turned up IP, HIDs, Flat Black, 11.00x20 singles.

      Comment


      • #4
        I just looked at the bottom end of my 3500 and the crank dimple is at 12 o clock and my cam line is at 12 o clock making #1 and # 4 pistons at the top of their stroke.

        Comment


        • #5
          yes, thats how all of the 60* v6 engines are.

          my problem is that when #1 is at tdc the lobes on the cam are not on thier base circle for the #1 piston. the problem is not with the crank, or the timing....
          3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe ALL FOR SALE (minus the car)
          96 LT4 6spd corvette. 355, AI 215cc LT4 Comp CNC Heads, Prope SRS pistons, Ported intake, ARH long tubes, Corsa Indy Pace 4:10 gears
          2012 Chevy Sonic Turbo 6spd
          1970 M35A2 Deuce and a Half, Spin on filters, Turned up IP, HIDs, Flat Black, 11.00x20 singles.

          Comment


          • #6
            a cam turns half speed of the crank, so you can be 180 off.. you are not on the compression stroke like you are looking for. im not 100% because im not lookin at it. but yeah it can be off
            94 Grand Prix
            3400- NX 75 shot, Cammotion cam, S&S headers, and a few more toys

            Comment


            • #7
              sorry i didnt read your previous post.. I dont know what it could be then
              94 Grand Prix
              3400- NX 75 shot, Cammotion cam, S&S headers, and a few more toys

              Comment


              • #8
                if #1 is at TDC and both valves are open slightly, that the TDC of the exhaust/intake stroke. you can have the timing marks off 180. rotate the cranke one more turn without the cam and see what happens.
                Andy

                sigpic

                fastest 1/8: 10.19@ 67.17
                fastest 1/4: 16.16@ 82.70

                62mm TB, 1.6 roller tip rockers, Ostrich 2.0, UD pulley, TB heater bypass, K&N, 180* stat, No cat, 99Grand AM dual cooling fans. 4T65E swap FDR 3.69, EP LSD, F.A.S.T. transmission controller, TransGo shift kit.

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                • #9
                  The stock cam doesn't have either valve on its seat at TDC with the cam timed properly. Valve overlap from the intake opening and exhaust closing will be during TDC. Spring the crank around 360 and the cam is 180, putting both valves on the seat for the combustion/exhaust event.
                  Ben
                  60DegreeV6.com
                  WOT-Tech.com

                  Comment


                  • #10
                    so its right the way it is...maybe i should be sleeping
                    3500, 1280 cam and PR, ls6 valve springs, port and polished heads, ported lim, ported uim, 4.3 70mm tb, ported trueleo headers and y pipe ALL FOR SALE (minus the car)
                    96 LT4 6spd corvette. 355, AI 215cc LT4 Comp CNC Heads, Prope SRS pistons, Ported intake, ARH long tubes, Corsa Indy Pace 4:10 gears
                    2012 Chevy Sonic Turbo 6spd
                    1970 M35A2 Deuce and a Half, Spin on filters, Turned up IP, HIDs, Flat Black, 11.00x20 singles.

                    Comment

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