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Thread: How to Locate TDC and Reset Timing Scale

  1. #1

    How to Locate TDC and Reset Timing Scale

    Apparently a self proclaimed DeLorean guru is telling people on Talk to stick pencils in their cylinders to locate Top Dead Center. With all due respect, there is a much better way to locate TDC on a PRV:

    TDC1.jpg TDC2.jpg

    Bill Robertson
    #5939

  2. #2
    Here's a picture of what's going on inside the engine (5/16" rod/drill bit/etc locating the counterweight hole):

    TDC3.jpg

    Bill Robertson
    #5939

  3. #3
    On the 3.0L, the timing scale is fixed, but I *think* I tried that trick a few years ago, and it did work. There is only a single blanking plug (which can be used with the crossover plug that I mentioned in the other thread). Definitely make sure to use the puffy-style washer here.

  4. #4
    For real excitement you should try timing vintage domestic vehicles with the timing mark on the harmonic balancer. The outer ring slips with age. On my truck with 230,000 miles the mark doesn't even point at anything meaningful anymore (Cylinder 5 IIRC). I just time it by ear.

    Speaking of which: even though we have single piece crank pulleys, DeLorean owners should still exercise caution timing their engines. Do not blindly assume that the scale is correct (can I hear an "Amen" Louis?).

    Bill Robertson
    #5939

  5. #5
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    oh hey guys, whats going on here? lol.

    No writing utensils are going in my cylinders, haha.

    I just mounted my waterpump the other weekend. However I have yet to put antifreeze in and this method seems like it would yeild a result i can be confident in. Thanks for taking the time to upload the pictures Bill!

    Matt, I can confirm the timing scale is fixed on the 3.0. I saw your thread on the washer, ill stop by toyota and pick one up.

  6. #6
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    Just another thought, if one person does this measurement for a 3.0, would it not apply for every 3.0? Due to the fact that the timing scale is fixed?

  7. #7
    I would think the most accurate way to find TDC is to make or buy the tool that threads a bolt into a spark plug adaptor. Then you rotate the engine CAREFULLY both ways till it hits that bolt, mark the locations and you get TDC between those two marks. Even using a dial indicator the TDC has no indication change for a few degrees at TDC.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  8. #8
    The problem with sticking things through the spark plug hole is the cylinder and piston are at an angle to the spark plug. The pencil is not going to stay horizontally still as the piston moves up & down. It should get you in the ball park well enough to start the engine, but it's not going to be precise enough to position the timing scale.

    Bill Robertson
    #5939

  9. #9
    Quote Originally Posted by MattDavid View Post
    On the 3.0L, the timing scale is fixed
    The 3.0 uses onboard electronics to time ignition. The flywheel has an offset bolt pattern so it's impossible mislocate the crankshaft sensor hole.

    Bill Robertson
    #5939
    Last edited by Greasy DeLorean Mechanic; 11-15-2013 at 09:03 AM.

  10. #10
    Just Plain Nuts Boo's Avatar
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    Quote Originally Posted by content22207 View Post
    For real excitement you should try timing vintage domestic vehicles with the timing mark on the harmonic balancer. The outer ring slips with age. On my truck with 230,000 miles the mark doesn't even point at anything meaningful anymore (Cylinder 5 IIRC). I just time it by ear.

    Speaking of which: even though we have single piece crank pulleys, DeLorean owners should still exercise caution timing their engines. Do not blindly assume that the scale is correct (can I hear an "Amen" Louis?).

    Bill Robertson
    #5939
    Amen Bill.
    Lou and "Boo" - The man you love to hate.

    Boo- The car you love to hate.

    ~~~~~~~~~~~~~~~~~~~
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    'Fastest naturally aspirated PRV'
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    3800sc swap
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    All original

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