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| kvom:
That's a good suggestion, Chuck. I'll try that next shop session. After dinner, I did a test on the one "good" head, as I described above. The seal is not perfect, as there's a very slight leak on both balls. When I activate the plungers, there is a very good air flow, so I think this one might work. I decided to reassemble the engine with just this head, add the pushrods, and see if I can get it to run on one cylinder. In a moment of absentmindedness, I dropped the brass couplers into the cam housing without inserting the balls first. :hammer: Then it was a royal PITA to get them out, a process which resulted in one of them flying off the workbench and into oblivion. So unless it shows itself there's at least one part to remake. Guess the lesson is don't work in the shop at the end of the day when you're a bit tired. |
| cedge:
Kirk Tapping a valve ball into its seat is a common practice in hydraulics. One sharp strike will usually deform the edge of the seat to fit the ball, giving a nice full contact fit and seal. I've fixed many an old valve that way rather than charging a customer for a whole new valve. Steve |
| ariz:
kvom you're really near the end of this complex build concentrate yourself, don't work whem tired :hammer: and solve the last problems we want see this beautiful engine running, and surely it'll run :thumbup: |
| kvom:
Thanks to a suggestion to seat the balls in the valve bores (from Cedge and Chuck Foster, thanks guys :thumbup:) by tapping them in with a drift and a hammer, I think I can get the valves to work. I did the first 4 before it was time for dinner and a rest. The seating isn't absolutely perfect in all of them, but hopefully good enough. I did find a few things for other builders to watch out for. First, the hole for the inlet barb isn't completely over the inlet valve bore, and the threaded portion of the barb is thicker than the valve cover. So when I tightened the barb I got leaks between the cover and the head. So when seating the balls I also gave the inside surfaces a rub with 360 sandpaper and Scotchbrite. I was also finding a fair amount of small swarf, including some round "wires" that seem to result from the drilling/reaming process. I made sure to pick these out with tweezers and also to blow air through all the passages. I think the wires are burrs created when drilling/reaming the holes for the plungers. I drilled these holes first and the valve bores last, but perhaps the order should be reversed. |
| kvom:
There are two sizes of balls used. The 3/16" for the valves, and 1/8" balls for the rod lifters. These small balls ride on the cam surfaces; the rod plungers sit on top of these; the pushrods connect the plungers to the rocker arms. Rather than any assembly drawings, Liney provides a set of transparent sheets with various assemblies drawn to scale. By putting these on top of each other you get an idea of how the parts interact. Today I spent a couple of hours in the shop. The first order of business was to make a new "flywheel", as the one I made from the end of an axle shaft was too hard to tap for a set screw. I made the one in the photo from a scrap piece of hex 12L14 steel. I drilled the cross hole 1/8", then counterbored with a #7 drill and tapped for the 1/4-20 screw. There are 3 #4 lead shot between the engine shaft and the set screw. After finishing seating the valves in the last head, I worked a bit on the pushrods. These are simply 1.4" lengths of 1/16" drill rod. I cut them a bit long with a wire cutter, then filed both ends flat and to length. However, my first fitting showed them to be a bit short. So now it seems that either I need to have longer rods, or else the valve plungers need to extend higher from the heads. The latter means that the springs may need to be longer. From the plans, the cams have a radius difference of only .05" between the open and closed valve positions. This means that the plungers will only move .05" to open the valves. Somy next shop session goal will be to determine where then plungers need to be in the closed position, and adjust to suit. |
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