Finding top dead center - Diesel Truck Forum -
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post #1 of 4 (permalink) Old 04-22-2007, 08:30 PM Thread Starter
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Exclamation Finding top dead center

Whats the easiest way to find top dead center. I have it marked on my harmonic balancer but people tell me its not accurate enough to change the timing. What do yall think?

98 2500,12V,5 speed,4x4,5" Stacks,airaid intake,#10 Plate,435 injectors,Haisley Firerings,FASS pump,Triple gauges,zoom clutch,Mickey Thompson wheels and baja claws.

07 3500 6.7,6 speed,4x4,afe intake,XRT,5in strait pipe.
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post #2 of 4 (permalink) Old 04-23-2007, 01:00 AM
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how did you originally find it to mark on your balancer?
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post #3 of 4 (permalink) Old 04-23-2007, 01:00 AM
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I was told the most acurate way is to pull injector #1 and use a small rod down the hole. So when it comes to the top with both valves up and just before the intake valve opens thats top dead center.
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post #4 of 4 (permalink) Old 04-23-2007, 06:05 AM
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There is a Timing pin that will fall into place when cylinder #1 is on top dead center. The problem is that pin can wear and no longer engage. If thats the case you'll have to use another method. I usually find when both valves are closed on the #1 cylinder, That is roughly TDC on compression stroke. Knowing that you are on compression stroke is key. Then adjust the exhaust valve down about 2 turns, rotate the motor in one direction until the piston contacts the valve and you can't rotate further (don't try to force it, you don't want to bend anything). Mark the harmonic balancer. Now rotate the engine the other direction until you contact the valve again, and mark the balancer. I usually mark on the right side(drivers side) of the position sensor, so you mark from the same point both times. These marks represnt TDC on the exhaust stroke either side of TDC compression stroke. Directly in between these two marks is top dead center on the compression stroke. Be very careful in determining what directly in the center is.

This way has worked for me, but if you can use the timing pin, that is the best most accurate way to do it. Good luck. let us know if you need any clarification.

2000 2500 reg. cab 4x4 auto 577hp
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