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Dumb question: How to use a TDC indicator??

Discussion in 'The Hokey Ass Message Board' started by Tugmaster, Dec 19, 2007.

  1. I just got a TDC indicator from Summit and I'm not exactly sure how to use it. I know you make sure #1 piston is coming up on the compression stroke and then screw the indicator into the #1 spark plug hole. Then what? I assume you screw the inner part all the way in and when the piston touches it back it out as you raise the piston until it no longer touches the piston?? Some one throw me a bone here.!!

    Thanks,
    Todd
     
    Deuces likes this.
  2. HotRodFreak
    Joined: Mar 25, 2005
    Posts: 1,935

    HotRodFreak
    Member

    The old simple method is to place thumb tightly against No. 1 hole with plug removed.
    Bump the starter slowly until max pressure is felt (you will know).
    That is TDC, or damn close.
     
    Deuces likes this.
  3. sdluck
    Joined: Sep 19, 2006
    Posts: 2,512

    sdluck
    Member

    Which kind do you have,Is this for with the head of or on? Give us some info if you don't have pictures.
     
    Deuces likes this.
  4. Ramblur
    Joined: Jun 15, 2005
    Posts: 2,101

    Ramblur
    Member

    By hand (well wrench actually) turn the engine till #1 piston hits the
    stop. Make a reference mark on the balancer or note reading on
    the degree wheel. Reverse the direction and turn motor till it hits
    the stop again from the opposite direction. Make another reference
    mark or note degree wheel reading. True TDC will be halfway
    between your two marks or degree readings. Hope this helps.
     

  5. The one I have is for with the head on. I do not have a harmonic balancer on the engine either.
     
  6. Ramblur
    Joined: Jun 15, 2005
    Posts: 2,101

    Ramblur
    Member

    What are you doing that you need to find TDC for? Could still mark
    the flexplate/flywheel to find it,but I'm not understanding the need
    too.
     
  7. Larry T
    Joined: Nov 24, 2004
    Posts: 7,659

    Larry T
    Member

    What's the Summit part number?
     
  8. I changed the cam and want to adjust the valves. the motor is on a stand. It is rebuilt and is basically a long block. not water pump, flywheel, harmonic balancer ect.
     
  9. SUM-900189
     
  10. Larry T
    Joined: Nov 24, 2004
    Posts: 7,659

    Larry T
    Member

    OK, if you don't have the balancer on the crank, you'll have to bolt a degree wheel on the front of the crank snout. Screw the TDC tool in the sparkplug hole. GENTLY rotate the crank counter clockwise until the piston touches the tool and stops. Set the degree wheel on 0. Then GENTLY turn the engine clockwise until it stops. Half way between where the degree wheel is now and 0 is TDC.
    Look at post 3 and 20 might help with the degree wheel.
    Larry T


    http://www.jalopyjournal.com/forum/showthread.php?t=215715&highlight=swirl+valves
     
    Deuces likes this.
  11. Ramblur
    Joined: Jun 15, 2005
    Posts: 2,101

    Ramblur
    Member

    If your just adjusting valves try IC,EO. Learned from an old time
    aircraft mechanic 25 yrs. ago and he swore it would work on any
    4-cycle engine. Always works for me. Works like this; while turning
    the engine in the direction of rotation as the "I"ntake valve is starting to "C"lose adjust the exhaust valve on that same cylinder. Continue your rotation and as the "E"xhaust valve starts to "O"pen adjust
    the intake valve on that cylinder. No problem remembering it,he
    taught us to remember IC as"internal combustion". The piston
    stop is mostly used to accurately determine TDC on a degree
    wheel when degreeing a cam,or verifying the TDC mark on the
    harmonic balancer lines up with the "0"on the timing tab.
     
  12. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    ...And on a Chevy it helps you avoid having to figure out if the timing tab you have is the correct one of the 43 available ones for your choice of the 16 different balancers, multiplied by random aftermarket parts mistakes!
     
  13. V4F
    Joined: Aug 8, 2008
    Posts: 4,114

    V4F
    Member
    from middle ca.

    if motor is apart (partially) , just put your finger on #1 intake lifter , rotate motor until the lifter is all the way down , roll the motor back & forth to be sure it is correct .............
     
  14. fastcar1953
    Joined: Oct 23, 2009
    Posts: 2,161

    fastcar1953
    Member

    13 year old thread.
     
  15. V4F
    Joined: Aug 8, 2008
    Posts: 4,114

    V4F
    Member
    from middle ca.

    did not read date ........... thanks
     

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