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Easy way to set valves

ISX
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ISX

ISX

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I set my valves today, figured I would show everyone how I do it. As long as you know the firing order and valve lash (which are both on the cummins id tag) you can set the valves. This is called the valve overlap method. Basically the pistons have running mates. Running mates are pistons that go up and down together in exactly the same positions, as in they both hit TDC at the same time. The difference is that one of them is on the compression or power stroke, and the other is on the intake or exhaust stroke. To find the running mate, you simply take the firing order and split it in half. Our cummins' firing order is 153624. So splitting it in half would mean 153-624. If you put the second number under the first, you would have 1/6 5/2 3/4 So 1 is 6's running mate and 5 is 2's, 3 is 4's. Since the running mates are 360 degrees out of phase, when one of the hits TDC compression/power stroke, the other is hitting TDC exhaust/intake stroke. This is perfect for setting valves because you can simply watch the running mate of one piston and it will be on the exhaust stroke with the exhaust valve open, when it hits TDC and transitions to the intake stroke, the intake valve will open. Once you see that intake valve move, stop. This is TDC, or as close to TDC as we need to be. The running mate will be on the very end of the compression stroke and the start of the power stroke and the valves will be on the opposite side of the cam lobe since they must be shut during the compression and power strokes. You can now adjust the running mates valves, intake and exhaust. For example. To do the valves on #1, you would watch #6. The #6 will open and close the exhaust valve and once the exhaust valve closes and the intake starts to open, you stop and now you know it is at TDC. Since 1 is it's running mate, you know 1 is on TDC compression/power so you can do both valves on #1. Now look down the line and you will see that the exhaust valve on #2 will be open. Since 5 is after 1 in the firing order, 5 will be the next valves you adjust, and since you watch 2 because it is 5's running mate, you will watch #2's exhaust valve close and start to open the intake, you stop and do the valve on number 5. Basically you will be turning the engine 120* to do each valve. You will do them in the same order as the firing order. Here is the reference order. Do 1 by watching the valves on 6. Then 5 by watching 2. Then 3 by watching 4. Then 6 by watching 1. Then 2 by watching 5. Then 4 by watching 3. The next one you watch will have the exhaust valve open so that will be a clue that you are doing it in the right order. It is a very fast and bulletproof way of doing it. It works on any engine also. Just split the firing order and stack them and you have your running mates like I showed earlier, it always works.

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Dieselpwrram

Dieselpwrram

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Great info. The video was a nice add to your write up. I had a heck of a time to locating TDC using the push pin. Last time I accidentally pulled the dam thing out of its bore. The other fear I had was breaking the plastic pin feeling for the drop hole.

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ranito2

ranito2

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My first time setting valves on a 52 ford 1/2 ton truck--my ? is as I go thru this way?? as i watch # 6 to set #1--will the first valve that move's apply to all as the exhaust side?? before I mess things up--:cool:

ISX

ISX

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My first time setting valves on a 52 ford 1/2 ton truck--my ? is as I go thru this way?? as i watch # 6 to set #1--will the first valve that move's apply to all as the exhaust side?? before I mess things up--:cool:

Is this on a 52 as in not a cummins? In any case, this will work as long as you know the running mates. I am not quite sure what you mean. If you are going the normal rotation, then the exhaust will open first. For instance, on the cummins the firing order is 153624, so if you rotated the engine normal direction (clockwise from the front), until the exhaust valve opened on #1, then you would keep going slowly until the intake opened on #1, at which time the exhaust valve would be closing. The exhaust valve closes as the intake valve opens..this is called valve overlap. This is TDC exhaust/intake for #1, so it's running mate (#6) would be on compression/power, so the valves would be completely shut so you can adjust the intake and exhaust on #6. Once you are done, you would crank the engine over 120 degrees and since the next piston in the firing order is 5 (153624), the valves on 5 would be the next ones to open and overlap.. That should be 120 degrees from where you were just at when you set #6 by watching #1. So the valves on 5 will overlap and you stop during overlap and then you can do it's running mate #2, which is on TDC compression power, so you do both valves on #2. Then crank another 120* watching piston 3, when it is on overlap you can set 4. Then crank another 120 watching 6 so you can adjust 1. Then 120 watching 2 so you can adjust 5. Then 120 watching 4 so you can adjust 3.. If you meant can you adjust more than one pair of valves at a time, you can but I don't know which ones. There is a guide based on TDC #1 and #6 which is as follows: When piston #1 is on TDC valve overlap (intake is opening/exhaust is closing, you stop at that point), you can adjust the Exhaust valves on Pistons 2,4,6 and the Intake valves on 3,5,6. Then you rotate the engine 360 degrees which will put #6 on valve overlap. Then you can adjust the Exhaust valves on 1,3,5 and the Intake valves on 1,2,4. However, this method is for a cummins inline 6 and unless you are doing this on an inline 6 with the same firing order, then I don't think this is valid (I don't know what you are doing it on when you mention a 52 chevy). http://articles.mopar1973man.com/2nd-generation-12v-dodge-cummins/20-engine-valve-lash-adjustments
  • 4 months later...
joecool911

joecool911

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I remember when I was young working at a dealership. The mechanics would rotate and watch for two rockers next to each other that would be full down position. Then there would be tow next to each other that would be full up. I'd adjust mine the same way. These were 4 and 6 cylinder with solid lifters.

ISX

ISX

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I remember when I was young working at a dealership. The mechanics would rotate and watch for two rockers next to each other that would be full down position. Then there would be tow next to each other that would be full up. I'd adjust mine the same way. These were 4 and 6 cylinder with solid lifters.

Yep, same principle. Cept you will never have them both full down unless there is something I don't know but usually the intake valve opens right before the exhaust valve closes, so they are both barely open.
ISX

ISX

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Just saw the warning to remove the timing pin before rotating the engine to adjust the valves. Where is the timing pin?

Between the injection pump and the vacuum pump. Its kinda back in there and is a PITA to get to so I never use it.

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ISX

ISX

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Now that turns this from an easy to a PITA project. Never heard of having to remove that before. Necessary?

Not for setting the valves it isn't. Just watch valve #1 for valve overlap. As in, clockwise the exhaust valve will open then close but right before it opens, the intake valve will start to open. Right when the intake valve starts to move, stop.. Counterclockwise (alternator method) the intake valve will be closing and the exhaust valve would be the one to watch start to move. Since the valves on #1 are both actuating, that means you can't do that piston at all. So on this page http://articles.mopar1973man.com/2nd-generation-12v-dodge-cummins/20-engine-valve-lash-adjustments you would do the valves labeled step 2 (bottom of page). Then make a mark on the damper in relation to something like the speed sensor, it can be very crude...then rotate the engine 360* and do step 1. Just remember to shake the valve side to side or up and down to make sure its loose, if it is down then you know you did something wrong. You cannot adjust lash on valves that are actuating!
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