1320

Can some further explain this. I read in searches that this is a easier method to located tdc for doing timing. If care is taken it is apperently as good as the other.

Lil Dog

The method is a good one as long as you have a barring gear for the fly wheel or similar way to make fine adjustments to the engine's crank angle.

The procedure calls for overadjustment of typically the exhaust valve on cylinder #1. The over adjustment of the valve will allow the piston to contact the valve near top dead center (TDC). The basic idea is to contact the valve once going clockwise, then rotating the crank counter clockwise to contact again. You would make two marks on the flywheel/damper from both of those contacts at a reference point (ie. pointer). Using a flexible tape you measure between the two marks (short distance, not the long distance) and 1/2 way is absolute TDC.

With that mark you can be assured to be at TDC. The problem with the damper is that the diameter is not large and you have to make small scribe marks, not fat paint or felt markers.

I am guessing the damper to be 8" in diameter..Thats about 25.13" circumference which breaks down to 0.07" per degree. Not much room for error there.


I hope this helps.

J-eh

Crimedog

When I did mine, I used a different valve method. You watch Cly. #6 until it is at crossover. The intake (front one) is going up, and the exhaust starts to go down. Right at the very point that the exhaust starts to go down is TDC. Make sure and triple check, I thought I was on, and then I was off 3-4 degrees. It is right when the exh. starts to move.

1320

crimedog, are you positive? It would be pretty easy to put a dial indicator on #6 exhuast valve, when it starts down, stop it and then go to timing.....

berner

When I did mine I got #1 piston coming up on compression. I tightened #1 intake valve down 3 turns and rotated the crank until I could feel the piston hit the valve. Then I marked it, loosened off the valve, rotated the crank well past TDC, tightened the intake valve 3 turns, and rotated the crank back until it stopped again. I marked it and loosened the valve off back to the proper adjustment. Then I rotated the crank so I could get at the marks from underneath the truck. I put a piece of masking tape on the balancer and cut it at each mark with a razor knife. Then I peeled it back 1/2 way and marked TDC.

Haulin_in_Dixie

That is not going to get real accurate unless you get an indicator in there somehow, like on top of the valve rocker to measure the pressure on the valve.

How about getting number one near top dead center and taking off the valve spring and put an indicator on top of the valve. Then just like on a gas engine for cam timing, mark it five thousands before and rotating the other way, five thousands after. Then the middle will be tdc, dead on.

infidel

With a dial indicator you can remove the #1 injector and do much the same with the indicator hitting the piston though the injector hole.

dsljunkie

Just so long as you dont break the plunger off in the cylinder . Why not just find TDC from the number 1 DV? thats how Ive always done mine . Works like a charm every time.
Scott

1ST CUMNZ

Would anybody have a link to a site where we can go to to find out different methods of doing the timing on a 12v.The reason being,looks like the dv method is not accurate.Or can someone explain (slowly) to this canuck the drop valve method?

DDD

First, ask yourself, “How accurate do I need to be?” The absolute best method for finding true TDC is to use some form of piston stop (valve or piston stop through injector hole if head on, something bolted to the deck if head off). This is the definition of TDC. Trying to back solve from the timing gears, injection pump, or valve timing will get close, but not perfect due to the stack up of tolerances in all of the components. Also, stopping the piston far before and after TDC, then splitting the difference to find the exact TDC will give much better results than setting up an indicator and watching the dial to see when the piston reaches its highest point. This might sound backwards, but it is true. This is because near TDC, a relatively large change in crank angle yields only a slight change in piston position. For example, +/- 2 degrees from TDC will only give around 0.002” of indication, but +/- 10 degrees from TDC gives around 0.047” of indication, making it easier to really find TDC.

Jim Fulmer

When I did mine I got #1 piston coming up on compression. I tightened #1 intake valve down 3 turns and rotated the crank until I could feel the piston hit the valve. Then I marked it, loosened off the valve, rotated the crank well past TDC, tightened the intake valve 3 turns, and rotated the crank back until it stopped again. I marked it and loosened the valve off back to the proper adjustment. 2 1/2 turns works and you can use the exhaust valve also.

Then with the engine past TDC break the pump gear loose then pull your pump pin plug, now with a mirror and light, back your motor up via alternator till the pin comes into view and pin it, now pull your pump gear, If you're into crunching #'s, measure the diameter of your balancer, multiply that by pi (3.1416) to get the circumference, Divide that by 360, Take that # and multiply it by how much you want the timing to advanced. This will give you the distance to mark the outside edge of your balancer. From under the truck rotate the engine past the TDC mark then back it up to the advance mark you had marked or take your measurement from TDC, now put your pump nut and (new) lock washer on after you clean the pump shaft and gear and tighten it up to 20/ft lbs or so, now pull the pump pin, turn it around and install the cap and tighten, with your T/Q wrench on the pump nut and your back up on the alternator tighten to 160 ft/lbs, put it back together and fire it up.

Jim

Haulin_in_Dixie

I have never done a Diesel but on the gas engines, I always used a stop with an indicator on top of the stop to measure the actual pressure placed on the stop which is really accurate.