How to find"dead nuts" Top Dead center on a 12v?
 

I need to know the way to find my TDC so i can double check my pump timing. I would love to know the other way. I can use my timing pin but there is a little play either way even with the pin engaged. I heard there is a valve drop method but what is it and how do you do it?
thanks

I did mine as follows

first I removed the #1 injector
rolled the motor up to the compression stroke of the #1 cyl
placed screwdriver down the injector hole
watched as the screwdriver rose up and stoped moveing
kept rotating the motor till the screwdriver started to fall down
then I turned the motor the other way keeping count of the clicks it took for the screwdriver to fall again
split the difference to find tdc

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then I marked the damper so I could find tdc easyer next time

that deffinatly doesnt sound as acccurate as my timing pin method. with my timing pin i was within .005 either way. but .005 is the difference of a degree of timing. so it could be anywhere from 14 all the way up to 16 the way i did it. There was that much play room even with the pin engaged in the hole.

when I had the head off I checked how close I was ... dead on

Did mine similar except used an extension on the dial indicator so that the tip rode on the top of the piston.

So you guys are checking TDC like this...correct me if im off...

method on the piston with dial indicator.
set it up so the dial rides on the piston.
rotate engine so when the dial starts to rize measure all the way till it stops, then measure all the way till it stops dropping...then right there in the middle of the measurment is the true TDC? if im way off let me know but it sounds good to me. I just want to make sure of my timing.

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Thanks the valve drop method seems like an ok way to do it.. but still not as precice as your dial indicator on the top of the piston idea.. that seems like it would be dead on. Thanks for the help

the dial should rise, than stop, and than start to drop. as soon as it starts to drop rotate the motor the other way. the dial should rise a little bit ( how ever much you let it drop), stop again, that start to drop. again as soon as it starts to drop stop turning the motor, split the difference and that is TDC

Here ya go....
From Dave Fritz's website....


TSB 18-10-94 Rev. A

And here is the CPL table with the proper amount of lifts needed for timing your truck....

Diesel Timing

the dial indicator to me is the best sounding method... cummins N-14 valve and injector timing is done with this method if you want extreme accuracy put a degree wheel on the crank... soon as the needle stops moving look at the degree wheel; keep rotating in the same direction, once the dial starts to move again look at the degree wheel again... split the difference on the degree wheel and that is dead dead dead nuts... cant get much more accurate than with the head off and doing the same thing... downside to the dial indicator is that it will stay still for X number of degrees of crank rotation so w/o the degree wheel you can get within like 4 degrees +/-