Ring the bell and get the kids in, it’s time for class.
First we need to tie up some loose ends. As to the oil in the two depressions in the head; thanks to Ken for his insight into that question. It now appears that this was in response to a problem noted in the field. Apparently, prior to October 1922 no lubrication was placed in these depressions. As a result of the problems noted by Ken the addition of the oil was the ’fix’. This is consistent with the note in the August ’27 CSN. I think we can close this perplexing subject out with the conclusion that oil is NOT to be placed in the depressions unless you have a freshly rebuilt engine, with guides installed and closely fitted to new valves, or you can hear ’squeaking’ noises coming from the valve train. Probably not a bad idea to squirt a bit of oil on the stems as you do your frequent oil can job on the rockers and the joint at the rocker adjusting bolt and the top of the pushrods.
EDITORIAL
{As this site has been in operation for well over a year, an abundance of information is contained in portions of the threads not revealed, when you go to a particular heading. For the new member it may not even be apparent that additional information has already been posted and available by a bit of additional work. I must admit that I am not completely versed in the operation of the ‘search’ mechanism available on this site. My point is that if you have a perplexing problem, that you need an answer for, you may find it is already posted, if you know the procedure to ‘find’ it. This is not to say that a revisit of a subject is bad, as it is not. With the addition of new members daily a new and different viewpoint may in fact be a plus.} (He now steps down from his box and returns back behind the teacher’s desk.)
With the rocker shafts and rockers installed on the engine it is time for the initial valve adjustment. (Credit to MrMack as he has already eluded to this next problem.) If the rockers arm faces are worn to the point of needing to be refaced the rocker arm bushings would be suspect also. That was true in this case. More movement was evident than considered serviceable. A new set of bushings and two new shafts were ordered.
To install new bushings the old ones must be removed. This is best done with a die grinder. With the grinder cut a path across the bushing from side to side. Make this grind in line with the shaft and not vertical so as to weaken the bushing if you over cut. After the cut is made it will be easy to extract the remainder of the bushing. To install the new bushings they must be pressed and not driven. A hydraulic press or even a vice may be used to gently press the bushings into place. If you try to drive them in you run the risk of distorting the very soft and fragile bushing. After they are all installed it will be necessary to resize them to the new shaft. If you are doing your own work a reamer can be purchased for a nominal fee. With a normal drill press or milling machine you can easily ream the bushings to the proper size.
What are we trying to accomplish when we adjust the valves? Ideally, we would like the valve to open to it’s maximum limit to either exhaust burned gasses or to receive the maximum charge from the carburetor. While at the same time when the valve is closed we want it closed securely so there is no leakage. To accomplish this objective we need the rocker arm to stay in contact with the end of the valve stem while the other end is following the movements from the cam lobes. However, when the valve is in the closed position the arm must NOT remain in contact with the stem. This would prevent the valve from seating properly. Therefore, we establish a “valve clearance” which we set between the end of the rocker arm and the top or end of the valve stem. For the engine we are working on the clearances are established as .006 for the intake valves and .008 for the exhaust.
To understand the adjustment procedure we need some given information. The firing order for this engine is: 1, 2, 4, 3. The arrangement of the valves from the front of the engine to the rear are: EIIEEIIE where E=exhaust and I=intake. (Don't worry if you start at the wrong end. The results are the same.)
You must keep in mind as you follow the procedure that this is the procedure for STATIC adjustment. Static means the motor is not running and in this case is an initial adjustment after a rebuild. To make these adjustments you do not need to install the distributor (you will understand why in later classes) and the two side covers should not be installed yet.
With the side cover still off we have a good look at the lifters and their guides. It is easy to determine which lifter is on a portion of the lobe on the camshaft and which lifter is at the bottom of it’s travel. The lifter lowest in it’s hole is at the bottom of it’s travel and the one to be adjusted. With your multiple feeler gage assortment select the .007 gage. Why the .007, because all we wish to accomplish in this adjustment procedure is to insure the engine will operate. FINAL VALVE ADJUSTMENT CAN ONLY BE ACCOMPLISHED WHEN THE MOTOR HAS BEEN RUN AND HAS ACHIEVED OPERATING TEMPERATURE. The other reason for selecting the .007 gage is that it is easy to find, is in better shape, because it is between the .006 and .008 on your gage assortment which are gnarled and beat up.
The procedure now is to slowly rotate the flywheel and identify the valves which are at the extreme bottom of their travel, and adjust the screw to the .007 setting. Tighten the lock nut on the adjusting screw. To make things simple use a piece of chalk or other marking device and mark the valve you just adjusted. Continue to rotate the flywheel until you have identified all 8 valves and adjusted them to .007. After the last one you should turn the flywheel through two complete turns and make sure each rocker arm is loose at some point in the two revolutions.
Put the two side covers on after gluing the gaskets to the covers and not to the block.
Place your chairs under the desk and recess.
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12/16/2001
