Easy Way To Find TDC

Discussion in 'Tips 'n' Tricks Topic' started by danthern, Jan 22, 2016.

  1. danthern

    danthern Veteran Member

    Aug 24, 2011
    opelika, al
    I'm sure I'm not the first to think of this but it came to me today as I was adjusting the valves after a lifter and PR change on my 79 350. With my finger over the plug hole I bumped the starter with a remote switch until I felt the air blowing, signifying the compression stroke. At that point I inserted my inspection camera into the plug hole and visualized the piston's rise. Had to go around a couple of times on some of them but it seemed to take some of the guesswork out. Any reason this isn't an effective method?
  2. COPO

    COPO Veteran Member Lifetime Gold Member

    Sep 15, 1999
    Ontario, Canada
    That's one way. Once it reaches the top it'll start to go down pretty quick. When you get close I would turn it by hand with a socket on the crank bolt with all the plugs removed and the trans in neutral if you have a 4-spd.
  3. sparkyboy

    sparkyboy Veteran Member

    Feb 4, 2015
    aurora, co
    That's actually the classic way to find tdc on any engine! That's cool that you figured that out yourself :)
    My favorite way when adjusting the valves on my 250 CI inline six is to simply pop the distributior cap off and rotate the engine -starter is ok until the rotor is at #1.
    Easy and no need to remove spark plugs! Only works on an old engine that has proper timing though haha!
  4. onovakind67

    onovakind67 Veteran Member

    Jul 8, 2001
    Fairfield, CA
    I just use the ICEO method.
  5. Z28zz383

    Z28zz383 Veteran Member

    May 11, 2012
    Saw on another 4x4 truck forum where a guy had hollowed out an old sparkplug and put a balloon over the end. It inflates on the up stroke and deflates on the down. Fairly trick way to do it when by yourself, shade tree style.......
    Cardinal likes this.
  6. badazz81z28

    badazz81z28 Veteran Member

    May 4, 2001
    Las Vegas, NV
    The best way is to use a piston stop. You thread it into the spark plug hole. Rotate the engine (by hand) until it stops by touching the piston. Reference the mark on the balancer. Rotate it the other way until it hits the piston. Reference the mark on the balancer again. The middle between those two marks is true TDC.
  7. Scott51

    Scott51 Veteran Member

    Jan 2, 2012
    New Zealand
    yep make your own piston stop out of an old sparkplug.

    Twist/break out the porcelain centre with a set of vice grips and punch then run a suitably sized tap down the now hollow centre. Cut the head off a corresponding bolt, slot one end to accept a screw driver the radius the other so it doesn't gauge the top of your piston.

    All of 5mins work out of some common leftovers, google DIY or homemade piston stop or top dead centre tool for a bunch of tutorials.

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