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How to locate tdc

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Old Nov 15, 2010 | 08:11 PM
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From: Southern New Jersey
How to locate tdc

I am going to be doing a valve adjustment on a pee pump motor this weekend and I was wondering if they have a pin to find tdc like our trucks have with the ve pump. I know this is a second gen question but there is much more knowledge here than there.
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Old Nov 15, 2010 | 08:31 PM
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Yes the pin is located behind the pump. It is kinda tough to get at.
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Old Nov 15, 2010 | 08:43 PM
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From: Southern New Jersey
Is it closer to the timing case or the back of the pump?
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Old Nov 15, 2010 | 08:51 PM
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From: A 5th dimension, beyond that which is known to man.
you can also watch the valves and not mess with the pin if you want. thats how i have been doing it.
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Old Nov 15, 2010 | 09:31 PM
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I have read that the pin is not completly representative of tdc as compared to watching the valves, or ultimately pulling #1 inj. and using a dial..Also the pin is sometimes frozen and I find the other methods pretty ez..
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Old Nov 15, 2010 | 10:53 PM
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pull the valve covers and watch #1 valves til theyare close to TDC, then put the the pin in, you might have to wiggle the dampner a little bit to get the pin in but it'll be pretty dang close to goin in that way.
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Old Nov 16, 2010 | 06:45 AM
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Originally Posted by IRoss
I have read that the pin is not completly representative of tdc as compared to watching the valves, or ultimately pulling #1 inj. and using a dial..Also the pin is sometimes frozen and I find the other methods pretty ez..
x2.
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Old Nov 16, 2010 | 07:27 AM
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From: Ida Grove, IA
Here is one way you can do it:

Get motor half way close the TDC. (watch valves) Tighten a valve/ rocker arm down several turns. Slowly turn the motor over until the piston contacts the valve, put a reference mark on the balancer. Now either back the valve off and roll the motor past TDC (between 45-90*) and tighten rocker back down the exact amount as before, OR leave the rocker where it is and roll the motor backwards until it contacts again (a little less than 1 turn). Reference mark the balancer again. Measure between marks, and the middle is TDC. WARNING: Only rotate motor by hand.

Or you can turn motor over until one valve is full open, and adjust the opposite. This way just leads to lots motor turning, but is more fool proof.
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Old Nov 16, 2010 | 09:11 AM
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Thanks for the info everyone I have one more question. How do I tell when I am close to tdc by watching the valves?
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Old Nov 16, 2010 | 09:13 AM
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From: A 5th dimension, beyond that which is known to man.
I copied and pasted this from the site i use.

"To locate TDC @ #1, watch #6 until it's at crossover (one rocker going up, the other going down at the same time). This is called the "companion cylinder" method. Adjust the proper valves, then rotate the engine over until #6 is at TDC, which means #1 will be at crossover. Gap the intake valves at 0.010" and the exhaust at 0.020."

When at TDC for #1, check: Intake 1, 2, and 4 Exhaust 1, 3, and 5

When at TDC for #6, check: Intake 3, 5, and 6 Exhaust 2, 4, and 6"
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Old Nov 16, 2010 | 11:59 AM
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From: Ida Grove, IA
I goofed earlier, you roll it back a little less then 1 turn not 2. I edited that.

If you are turning the engine over (in the direction that it runs) and watch for the #1 intake to close, you will be coming up on TDC. You can tighten the valve up and continue turning until it contacts.

If you are just going to set the valves, you don't really have to find exact TDC.
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Old Nov 16, 2010 | 12:04 PM
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Originally Posted by CaptainChrysler
If you are just going to set the valves, you don't really have to find exact TDC.
That is correct, the valves just have to be completely closed. There are a few degrees on either side of TDC, on the compression stroke, that the valves are completely closed. One way to check is to make sure that the rockers are loose on the valve. This will not work if the valves are too tight and there is no clearance...Mark
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Old Nov 16, 2010 | 12:12 PM
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Thinking about this, if you are not exactly on TDC od #1, thenyou will have to readjust a little for the other valves, for example intakes 1, 2 and four, if you are not on TDC for #1, 2 and four may not be completely closed. just check and turn the engine until there is play in each valve that you are adjusting...Mark
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Old Nov 16, 2010 | 12:18 PM
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From: Southern New Jersey
Ok I think I got it makes me love my ve pump even more tdc is so easy to find lol.
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Old Nov 16, 2010 | 03:23 PM
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From: A 5th dimension, beyond that which is known to man.
yeah theres a lot of "base circle" on the cam that you have to adjust on. you dont need to be perfectly degreed at 0.
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