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Top Dead Center on Ty w/4.3

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  • Top Dead Center on Ty w/4.3

    I am intstalling a new distributor, timing chain, water pump and main seal.

    As I was removing the crankshaft pulley, I determined the harmonic balancer is broken. The outer shell just came off.

    I want to ensure the engine is at TDC, however the Chilton's manual suggest that I use #4 as a reference. My mind and everywhere suggest using #1 with the rotor button pointing at the #1 spark plug wire.

    I understand the following:
    -remove the #1 spark plug
    -turn the engine over until I hear the air escaping on the compression stroke and #1 plug is at it's highest point.
    -the rotor should be point at the #1 spark plug wire
    -the Two demples on the crank/cam shaft should line up close with crankshaft demple being at 12 oçlock position and the camshaft demply being at the 6 o'clock position

    If what I think I know isn't correct can someone steer me in the correct direction?
    Justoyz Racing
    808-542-2496

  • #2
    Re: Top Dead Center on Ty w/4.3

    If you have the valve covers off (duh) and if you understand what is meant by "valve overlap" then put #4 on overlap and # 1 will be at or very close to TDC. This with cam timing properly set to begin with of course. IOW the dimples should line up virtually perfectly.

    HTH
    If you can't fix it with a hammer you've got an electrical problem.

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    • #3
      Re: Top Dead Center on Ty w/4.3

      the new balancer will also verify tdc with the timing marks. just like don said .Can tell with valve timing at the same time .
      92 TY#1473 blk/blk single turbo ls 411 pcm / 4l80e



      92 ty #1517 wht / silver srp's ,eagles ,pte 51, mild vortecs , 412 comp , 4l80e swapped w/2600 tcs .

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      • #4
        Re: Top Dead Center on Ty w/4.3

        Your on the right track ..

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        • #5
          Re: Top Dead Center on Ty w/4.3

          I think you all are missing what I am doing:
          -vavle cover doesn't have to be removed to install a dist and timing chain
          -the harmonic balancer is broken; the outer weight is no longer connected to the balancer.. can't be used to determine TDC with tick marks...

          Question is this: do I use #4 or #1? Chilton's manual suggest I use #4. Videos on youtube suggest I use #1, which do I use?
          Justoyz Racing
          808-542-2496

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          • #6
            Re: Top Dead Center on Ty w/4.3

            That's what you get with a Shilton's manual. I'd suggest getting a hold of a set of factory service manuals, they are invaluable on a stock truck. Use #1 for your timing.
            1991 Syclone Best 10.95@122.5 Tuned by Nolan
            2002 GMC 2500HD 8.1L
            2002 Subaru WRX(sold)
            1974 Scout II Runnin' on 38's

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            • #7
              Re: Top Dead Center on Ty w/4.3

              If you have the timing cover on. Install your balancer. Rotate your engine until you feel the compression stroke. Which is the air exiting no.1 plug hole. The exhaust stroke will push air also but it will not be as strong as the compression stroke. When you feel the strong compression stroke air escape. The line on the balancer will be close to zero on the timing tap. Go ahead and align the balancer mark with the zero on the timing tab. You will be at top dead center.

              To install your distributor it will not drop all the way in because the rod that turns your oil pump will not be lined up with were it needs to engage the bottom on the distributor. You will either have to take a long screwdriver and turn the oil pump shaft until it lines up with the distributor while the rotor pointing at number one cylinder. Or you can drop the distributor in as far as it will drop. Point the rotor towards no. 1 cylinder and snug the dist. clamp down just enough to keep the dist. from popping out. Then bump the starter. The dist. will turn and engage the oil pump shaft. The dist. has to be held down enough the keep the gear engaged with the cam when the starter is bumped. But not tight so it can turn to engage the oil pump shaft.
              Last edited by wildphil; 02-18-2013, 09:51 PM.
              Phil
              91 Syclone 2097
              92 Typhoon 0042 Black/Black
              93 Typhoon 1955 Royal Blue

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              • #8
                Re: Top Dead Center on Ty w/4.3

                All of the above. Once the dist is installed (all the way down) initial timing can be done using either 1 OR 4. The mark will be correct with both. You just have to use which cyl in on compression or you'll be 180* out and it won't start. The rotor can point anywhere. Set the "star" points on the reluctor so they line up with the points on the stator for your initial positioning. Just call that spot # 1 and install the wires clockwise from there in the correct firing order. 165432 Number 1 is "supposed" to be the the connector straight ahead towards the manifold but it actually doesn't matter. Your wires should all reach.
                If you can't fix it with a hammer you've got an electrical problem.

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