Using a Dial Indicator

[동쪽의돌-안동석]

Using a Dial Indicator

Originally written by Scott Blackburn
Reproduced and illustrated by Mr Tidy

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The process of adjusting our valves is not that hard if you understand what is going on and why we are doing it this way. Yes we have hydraulic valves and it's said "hydraulics' need no adjustments. But, we have 2 valves per intake and exhaust ports. When we have a noisy valve train, part of the problem could be that the valves of any one intake or exhaust port could have one or more valves opening and closing at different times. The excessive tolerances when the valves are out of adjustment create some of this excessive noise.

The ideal set up is to have both valves of a particular intake or exhaust open and close at the same exact time.

When this situation exist then we will have a much quieter valve train. To obtain this, one of the best ways to set our valves is to use a dial indicator for an adjustment to the "Nth" degree or as we say "Zero Tolerance".
 

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Preparation: We need to apply a dial indicator to rest upon a rocker arm finger in a stable manner as the slightest deflection of the mount will give false readings. I use a magnetic base and mount it to a suitable place on the frame to hold the dial indicator. The indicator tip will rest upon a rocker arm valve tip finger or upon the push rod finger portion of the rocker arm. The latter is where I usually prefer to position the dial indicator.  For this animated demonstration the dial indicator will appear upon the nonadjustable rocker arm finger. Before we start loosening valve tip adjusters we should first check to see if our valves are out.

Let me inject here again and add that, in this article here when we put a .005 feeler gauge under a rocker arm finger the indicator will read .005, in the real world when we consider the fulcrum and pivot point, as we have with the rocker arm fingers and rocker arm shaft, and the laws of physics we know that if the dial indicator isn't the equal distance from the pivot point as the valve tip,  then we might read .004 for example instead of .005 . Not trying to confuse you but when you actually do it, you will have been forewarned and hopefully not scratching your head as to why the readings aren't the exact measurement of the feeler gauge.
 

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Figure 1: This shows the indicator set to "Zero" on the indicator dial. 

• The left most finger is resting upon the valve trip.
• The right most finder, (the adjustable rocker arm finger) is not resting upon it's designated valve tip (this we don't realize as of yet). (refer to animation)

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Figure 2: In figure 2 the rocker arm is opened enough to slip in a feeler gauge.

Let me point out here that the thickness is not an issue as the feeler gauge is just a *standard for the adjustment of the valves.

* Standard: meaning it is a constant value that will not change from one area to another.   For this application we are going to use a .005 (5 thousandths) feeler gauge.
 

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Figure 3: In this figure we slip a .005 feeler gauge under the left most valve finger. (note the indicator shows .005) (refer to animation)

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Figure 4: Here we put the same .005 feeler underneath the right-hand valve finger.

Notice here that the dial indicator only reads .003 .   This indicates to us that there is a .002 thousandths difference between the left valve finger and the right finger.

If the readings had been the same the valve adjustment would have been OK and no adjustments would be needed.   

Since they are off we will proceed.  (refer to animation)
 

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Figure 5: This figure shows the feeler gauge removed. The dial indicator is upon "Zero" and we've loosened the lock nut on the right hand adjustable valve finger and screwed the adjuster tip down to meet the valve tip.  Then re-tighten the lock nut.  Take note here that this is where your sense of touch will be of the utmost beneficial use. If you adjust the tip too far downward then you will begin to lift the leftmost finger tip upward causing an out of adjustment condition in the opposite direction.  When you first feel the adjuster tip make contact with the valve tip, stop.  (refer to animation)

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Figure 6: Here we are opening up the rocker arm assy again to apply the .005 feeler gauge.

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Figure 7: Here the .005 feeler gauge is applied under the left most finger, it reads .005 (refer to animation)

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Figure 8: Here we move the .005 feeler gauge to the right-hand finger tip and again check our  reading. Note here that it also reads .005 on the indicator. 

This means that both fingers are equal and will touch both valve tips at the same time (this situation is as shown in figure 5 as well).

As the push rod applies pressure to the rocker arm assy the valves will both start to open at the same time as well as close at the same time. 

If the reading are not the same then you need to repeat step 5 through 8 again till you acquire the same readings on the dial indicator on both sides. (refer to animation)
 

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