Actual Degrees of Valve Actuation

[ISX]

I put a dial indicator on top of my valves, did some fancy work to find exact TDC (have movie, need to edit), and found when the valves opened/peaked/closed and marked them all on the damper. I did some fancy calculations and came up with my numbers on what happens as the engine turns.I will start at the power stroke, the diesel blows up and the piston goes down, 60* before the piston hits the bottom of the power stroke, the exhaust is already opening. The piston then goes up on the actual exhaust stroke with the exhaust valve peaking at 113* before the piston reaches TDC on the exhaust stroke. At 12* BTDC Exhaust stroke, the intake valve starts opening. At 12* past TDC on the intake stroke, the exhaust valve is closed. 91* into the intake stroke, the intake valve peaks. The piston continues down then starts back up on the compression stroke. 13* into the compression stroke, the intake valve is closed. Exhaust Valve total duration is 252*Intake Valve total duration is 206*Valve Overlap is 24*Everything is in crankshaft degrees, NOT camshaft degrees. Camshaft degrees would be half of what I just wrote since it moves half the speed. So 180* rotation on the crank is only 90 on the cam.This was with my valves at 0.008" Intake and 0.015" Exhaust.

[Mopar1973Man]

Very interesting to say the least...

[Wild and Free]

So lay that over the top of your thread on easy valve lash setting and tell us what you find there. What I am getting at is are all of the valves being adjusted when they are on the bottom side of the cam or are some of them being adjusted during part of the duration cycle yet? You where adjusting them when they were both loose and one or the other could still be on the end of a lobe ramp or end of duration cycle and not quite to bottom of cam lobe and not resulting in a truely accurate adjustment. If you look at a dampner from a large cummins the degree marks for setting valves and injectors are on the dampner alreaday like what you are finding here. Just not always noted as degrees just have letters and numbers for reference though. Just throwing this out there also is that when doing valve adjustment by rotating the engine over by the alternator is rotating the engine backwards and the gear lash which isn't much does affect the results of the valve adjustment also. Take time and set up a dial indicator on top of a push tube and try it and you will find slight differences. Try that on a bigger engine when doing injector settings and you will have a really bad running engine if it even starts.I'm just sayin.

[dorkweed]

So lay that over the top of your thread on easy valve lash setting and tell us what you find there. What I am getting at is are all of the valves being adjusted when they are on the bottom side of the cam or are some of them being adjusted during part of the duration cycle yet? You where adjusting them when they were both loose and one or the other could still be on the end of a lobe ramp or end of duration cycle and not quite to bottom of cam lobe and not resulting in a truely accurate adjustment. If you look at a dampner from a large cummins the degree marks for setting valves and injectors are on the dampner alreaday like what you are finding here. Just not always noted as degrees just have letters and numbers for reference though. Just throwing this out there also is that when doing valve adjustment by rotating the engine over by the alternator is rotating the engine backwards and the gear lash which isn't much does affect the results of the valve adjustment also. Take time and set up a dial indicator on top of a push tube and try it and you will find slight differences. Try that on a bigger engine when doing injector settings and you will have a really bad running engine if it even starts. I'm just sayin.

What you describe is the "best" way to do it............however, what ISX was doing was just to give us some info on the valve "timing" of our engines. I'm still amazed that the exhaust valve starts to open that soon!!!!! I'm a wonderin' if that's not to "lessen" the spike in cylinder pressure because the 1st gen trucks have higher compression ratios than do the 2nd and 3rd gen engines???!!! The 3rd gens lessen the peak cylinder pressure by the "multiple" injection events..........but they also "prolong" the "power stroke" of ignition by the "multiple" injection events!!! It works........that's all I know for sure!!

[Wild and Free]

What you describe is the "best" way to do it............however, what ISX was doing was just to give us some info on the valve "timing" of our engines.

I realize this, I was just asking him to do even more with all of what he does to make sure what he has previously posted is accurate and to confirm or prove or disprove some things. Valve timing is directly linked to a proper valve lash setting. From experience with bigger engines and setting overheads with dial indicator is that even when both intake and exh valves are loose you can't visibly see them move anymore but while rotating the engine it can take for example only 20*rotation to get to the bottom of the cam. which is so subtle you can't see the last .005" of movement. This is just an example. I would like him to experiment with this and see how it comes out.

[AH64ID]

Some info on the OEM cams

[ISX]

In an hour or 3 I am going to redo it to make sure. I kinda used a crappy sharpy to label what was what and after I took the damper off I noticed I was writing on top of oil. I could tell what everything was for the most part. The measurements are accurate I just don't know about which thing was which but everything is still out there and marks are still there so I am going to do it again after I clean that damper completely off so that I will be able to tell for sure. 99.9% sure it is right though. I will get a lift measurement (at the current 8 intake/15 exhaust) and then I will set the valves to 10/20 since that is what it's supposed to be and I will redo everything again and get numbers for that.Wild and Free, that is a great idea. I did all of that stuff just by rough calculation, now I can do it dead nuts. I also want to get a chart or something going that is a lot better looking than a big paragraph, ran out of time though.

[jlwelding]

Mike and I kinda hit on the subject this morning, I played around with the 7 - 17 the 8-18 the 12- 22, and from my experince (old motor) the 12 -22 I thought ran better. Not talking hp or anything but just daily driving. While on the subject, my new motor the valve lash was really cool. I checked the intakes before adj. and they where all 14 then checked all the exhaust 24. I thought that was weired that they where all 4 th diff. intake and exhaust. This motor I know has never been adj. I still talk to the owner. The mileage is 180k before valve adj. I also dont like the rotate of the motor backwards to adj. valves:shrug:

[ISX]

Today I set the valves to stock 10/20 so it wouldn't be my weird 8/15 setting. The previous readings are right as well. I forgot I couldn't do lift because my dial indicator is only 1/4" and although I could have just reindexed it a bunch of times, I didn't want to lol. Readings are not too different, valve overlap is. I will try and get something up tomorrow, have some other things to get done tonight.

[jlwelding]

Good info, keep up the good work:smart:

[ISX]

Made a chart this morning, not what I wanted but don't have time to make what I really wanted to do (will try tonight). I still need to edit and upload the video of how to find true TDC. Once I found it on mine I actually took it to the mill and made a mark. The end mill is only 1/8" wide and the cut is only about 1/16" deep so it shouldn't mess with the RPM sensor. Basically the center of the cut is TDC when lined up with the edge of the RPM sensor.

[ISX]

Well this took me long enough but I finally got it all figured out. The numbers mean how many degrees the damper has to rotate before the valve starts to move, this is either direction, not just rotating it clockwise. The red numbers are the valves you set in the book method, the green ones are the open valves. The open valves are percentages showing how far the valve is open, so fully open is 100%.

[jlwelding]

(Layman) So do we keep going by the book?

[ISX]

(Layman) So do we keep going by the book?

Yeah, you can screw up TDC pretty badly and still be fine. The closest ones are the 113 ones, so you don't even need to do anything fancy to find TDC like taking the timing gear cover off and matching the dots or pushing in the timing plug. All you gotta do is bar the engine over, if you are going clockwise you would watch #1 or #6 (depending on which TDC you are on) and watch the exhaust valve close and once the intake starts to move, stop. Actually that will get you really close to TDC. Then do the same thing for the other TDC by watching the opposite valves, so if you watched 1, watch 6. Now using the alternator, you would watch the intake valve close and stop when the exhaust started to move, because it rotates counterclockwise. But yeah, all the people spending hours getting the timing plug to move just to set the valves (12v thing) are wasting their time. It doesn't need to be any more accurate than the way I just mentioned, and even the way I mentioned is probably more accurate. I heard that the plug can be off actual TDC. So you can't use it for timing since it can be off, and it isn't necessary for valve lash since it doesn't need to be any more accurate than the way I just mentioned. You could just feel the valves on #1 and #6 and as long as both of them are tight on one of the pistons (valve is being pushed down, and since it is both then they are on valve overlap), you are good to go. They will be loose on the other piston. That's all the more accurate it has to be, and you can even screw that up a little and be fine. I mean you got 113* damper rotation (damn near a 3rd of rotation) before a valve starts to open, if you can screw up that badly then your pretty talented.

[jlwelding]

Ok check this out, I may be doing this wrong. What I have done in the past with motor cycles is as soon as the intake goes all the way down and back up that is susposed to be combustion on #1. And thats how I have started with adjustment. But the eng. is turning over back wards when you bar it over with the alt. So can someone give me the guidance to do this right?

[ISX]

Ok check this out, I may be doing this wrong. What I have done in the past with motor cycles is as soon as the intake goes all the way down and back up that is susposed to be combustion on #1. And thats how I have started with adjustment. But the eng. is turning over back wards when you bar it over with the alt. So can someone give me the guidance to do this right?

If the engine is turning over backwards the cycles would be

[*]Intake

[*]Exhaust

[*]Power

[*]Compression

[*]Intake

[*]Exhaust

[*]...

So going backwards when the intake got back to the top, you would actually be a few degrees into the exhaust stroke. This will work fine but since the one you watched will now have both valves loose (because you are on valve overlap), you would do it's running mate. So if you watched #1, you would adjust the lash on #6, and all the valves that you adjust with it that are shown in the manual. Then you watch number 6 so you can do 1 and all the valves you adjust with it.

If you watch that intake valve while you go backwards, you will see once the intake valve comes back up that the exhaust starts to open before the intake is all the way back up. This is the valve overlap and ideally you would just stop once you saw the exhaust start to move but it really doesn't matter. Either stop when the intake is fully closed or when the exhaust starts to open, either way you have 113* on the damper room for error..

As far as the intake valve going back up and when it is finally fully closed being in the combustion, the piston you watched that happen on would be 10* into the compression stroke, and it's running mate would be 10* into the exhaust stroke. That is going forwards, now if you went backwards with the alternator, the intake valve would go up and close 6.2* into the exhaust stroke, and it's running mate would be 6.2* into the compression stroke. So no matter how you look at it, none of them are on combustion.

[jlwelding]

So the way I do adj. is ok? i think I got it, no matter foward or back it's still the same.

[ISX]

So the way I do adj. is ok? i think I got it, no matter foward or back it's still the same.

Your method will only work with the alternator (cranking the engine backwards) as the intake valve will go down and come back up at the point of valve overlap. If you went forwards the valve would go down and back up and you will be close to BDC on the bottom of the compression stroke. So if you do it, make sure your cranking the engine over backwards. Or just watch the exhaust valve and make sure the valves are overlapping, it's not that hard to watch a valve an inch away