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timing advance

Discussion in '1969-1972 K5 Blazer | Truck | Suburban' started by 69K5, Apr 21, 2002.

  1. 69K5

    69K5 1/2 ton status

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    why would you advance timing?my new timing set has 3 marks standarad +4 and -4

    nathan
     
  2. chevyracing

    chevyracing 1/2 ton status

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    The marks on the timing set are for Degreeing a cam more than likely. If you are not running a very radical cam forget about them and zero it up.

    John
     
  3. skyblazer

    skyblazer 1/2 ton status

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    The marks are for customizing your valve timing. The specs on your cam card are for straight up timing (marks lined up). In some circumstances you may want to advance or retard timing (for example, advancing timing allows the intake valve to close earlier and increases compression for more torque). Just depends on your engine and parts combination.
     
  4. 69K5

    69K5 1/2 ton status

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    . I do want more torque but dont have the cam and everything else is stock rock. So i will just zero it up .

    thanks for the help

    nathan
     
  5. Steve_Chin

    Steve_Chin 1/2 ton status

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    There are a lot of reasons to use the non-zero keyway, but in most cases, you will want to use the zero keyway. Advancing the camshaft timing will lower the RPM band in which you make peak torque, lowering the power band. This is useful to some guys who run big cams and need a little more bottom end oomph. Retarding the cam will increase the RPM of the torque curve, increasing the power band. This is useful to guys who have so much lowe end torque that they blow off their tires or break drivetrain parts. On DOHC engines, you can alter the lobe separation angle by moving one cam in respect to the other, changing the operating characteristics of the engine still further. Increasing LSA tends to widen the power band at the expense of peak torque and power, while narrowing the LSA tends to narrow the power band and add to midrange power. In a 4x4, we generally want a wide LSA, especailly if we're running wide-ratio manual trannies. Automatics with high stall torque converters are more forgiving of narrow LSAs in a heavy vehicle.
     
  6. 69K5

    69K5 1/2 ton status

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    Steve

    I think i understood all of what you said. It always amazes me how much you know and can explain. A while back you corrected me on some bopdy mount bolt torques. you were write. i read the wrong book. i was looking in the 74 fsm.

    thanks for the help

    nathan
     

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