Timing marks on the timing set....help.

Discussion in 'Engine Topic' started by shawntmartin, Apr 17, 2006.

  1. shawntmartin

    shawntmartin Veteran Member

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    Dec 29, 2005
    Sorry guys, I deleted the other post and replaced it with this one because the other post started off with another topic and ended with the topic in this post. I figure more people will reply with this new title...

    My only question right now is... is the #1 piston ever at TDC when the crank dot is 12:00 and the cam gear dot is at 6?

    I installed my timing set (crank 12/ cam 6) but I didn't think about the fact that the crank goes around 2 full revolutions in 1 cycle, which means it will hit 12:00 twice during its cycle... when lining up the dots (crank12/ cam6) does it matter which one of these revolutions is taking place when stopping the crank at 12? Please tell me it doesn't matter because if I have to change things then this will be the 3rd time tearing the engine apart..
     
  2. manicmechanic

    manicmechanic Veteran Member Lifetime Gold Member

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    Oct 24, 2000
    Tulsa, Oklahoma
    If I understand your post you should be good to go. You can either set it up the way you described 12/6 dots directly across from each other or you can set it up as Crank 6 cam 12 dots in line but at oppsite ends of each other.
     
  3. shawntmartin

    shawntmartin Veteran Member

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    Dec 29, 2005
    Sorry, I don't to be confusing... the crank gear stops @ the 12:00 position twice during its 2-360degree revolutions (1 cycle). I'm using one of these 12:00 positions to line up with my cam gear (6'oclock). Does it matter if i use the the cranks first 12oclock rotation (which would be 1/2 way through a complete cycle/ 360degrees) or does it matter if I use the second 12oclock position (the end of a complete cycle /720degrees)
     
  4. manicmechanic

    manicmechanic Veteran Member Lifetime Gold Member

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    Oct 24, 2000
    Tulsa, Oklahoma
    As long as the #1 piston is at the top of it's stroke, that will become TDC when you install the cam. The crank doesn't know if it's on compression or exhaust stroke until you install the cam. As long as you align the marks as outlined you will be OK. Make sure to rotate the assembly after you install the cam and hook up the chain to make sure the marks come around and line up again.
     
  5. shawntmartin

    shawntmartin Veteran Member

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    Dec 29, 2005
    I already have everything buttoned back up except for the cylinder head on the #1 piston side. Is there a way to check the timing mark, piston position, and / or lifter positions...to see if these dots line up when spinning it around? If the timing set is installed right, wouldn't I have both lifters all of the way down in their bore when at TDC?
     
  6. manicmechanic

    manicmechanic Veteran Member Lifetime Gold Member

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    Oct 24, 2000
    Tulsa, Oklahoma
  7. Marv D

    Marv D Veteran Member Lifetime Gold Member

    Ohhhh, boy, we are going to drive everyone nuts with this. ;)

    Look let's make this simple. Install the timing set dot to dot! Then after the heads and intake are on, pull #1 plug, put your thumb over the hole and and rotate the motor till you feel compression building in #1 cylinder. Bring the timing mark to 10-12° before TDC and put the stinking distributor in and point the rotor towards #1!
    Once the cam is in, and the timing set is installed, you don't care where the dots are.

    It is just a FYI that when the timing set is dot to dot, your not at TDC ready to fire #1, you are on the exhaust stroke. If you installed the timing set dot-to-dot, or both dots at 12 o'clock, it doesn't matter, you are still accomplishing the exact same thing. The crank doesn't care, the order that the pistons come to TDC are the same. It's just easier to visually line up the dots when they are dot to dot.

    Look, not trying to belittle anyone, it's just that this issue is of no significance by the time your ready for the distributor.
     
  8. Damon

    Damon Veteran Member

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    Nov 16, 2000
    Philly area
    The pistons for both 1 & 6 always hit TDC at the exact same time. It's just that one is at TDC COMPRESSION and one is at TDC EXHAUST. Whether you installed the cam dot-to-dot or 12 o'clock-to-12 o'clock will just determine which of those cylinders happens to be TDC on Compression.

    Dot-to-dot = TDC compression on #6
    12-to-12 = TDC compression on #1 (ready to drop distributor in for firing #1 plug)
     

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