Making Split Pins
At one time, I'm sure you could walk into a hardware store ("ironmongers" they were called in my youth) and say "two one-thrity-second cotter pins please". Well let me tell you that progress has put a stop to all that nonsense! The Feeney valve springs are of the "hair pin" variety that I've heard termed "zero-rate". A detent in the top of the spring engages with a cotter, or "split" pin inserted through the hole in the top of the valve stem, holding the valve closed. A side effect of this arrangement is that the valve cannot rotate, so it only has to seat in one position. I guess the downside is that in not being free to rotate, there is no wiping action available to remove particles that might interfear with the seal. At any rate, with no commercial product available, I decided I'd have to make my own.
Cotter pins are made from half-round wire, so step one is to make some half-round wire. This requires a jig to hold the wire while it is ground or filed down. A simple V cut will suffice and if it is made to the correct depth, the jig can also be used as a gauge. If you draw this out, the depth of the V cut can be determined by CAD, or simple trigenometry if you're too lazy to fire up the computer.
I was (too lazy too lazy that is), and the answer arrives to us by way of the ancient Greeks as the hypotenuse of a right triangle whose other sides are 1/64" long (who needs computers?) Here we see a block of steel from the scrap box, set over at 45 degrees, squared up to the mill axis, getting a V groove milled to a depth of 0.023". Since we are milling down the flank of the V, this is another right triangle with both sides 0.023", so the down-feed required is 0.032". Funny, that's the wire diameter. Wonder if there's a trig relationship I don't know, or have forgotten involved here...
A length of 1/32" music wire is clamped in the block V (by a convenient screw in the case of my scrap box special) and filed down by stroking away from the clamping point until the file contacts the top of the block for the entire length. This provided enough half-round wire to make two pins. The wire could be anealed at this point, but I decided to leave it tempered, just in case this damn thing actually runs.
The pins are formed by bending lengths of the wire around a 1/16" mandrel to form a U shape, springing the ends together to poke them into a slightly oversize hole in a scrap steel bar, then, with the mandrel in place, hammering the pin down until it can go no further. When removed, a very neat looking pin results as seen here. I love it when a plan comes together, even if I did break a drill making the hole in the scrap bar!
Seating the Valves
Trial assembly time. The valves are inserted and the pins pushed through the valve stem holes. The hair-pin springs are inserted from the rear. First the detent is engaged with the cotter, then the ends are raised and pushed forward with needle-nose pliers until they snap into the tiny blind recesses drilled in the tops of the valve port tunnel. I tried the other way—holding the spring compressed while vainly attempting to insert the pin—forget it. Humans lack sufficient hands to do the job this way.
Now you can block off the plug-hole and blow into the bore. If air escapes, one or other valve is not seating. Find out which by closing off the ports. If the seat has been "lapped" adequatly, there's no point trying to fix it by more lapping. Besides, Bruce Satra says that the smaller the width of the seat band, the better. The seat needs to match its actual valve. I was stumped until Bert Streigler related how he used to seat new valves into Model A Fords: make a wooden dowel about the diameter of the valve head. Place the valve in position in the head, position the dowel over the valve head, then belt the other end of the dowel with a carefully calibrated hammer. In despiration, I tried it, and and to my surprise and delight, it worked just fine (note to self: trust whatever Bert says, regardless). After the requisite number of calibrated wacks, I could play the valves like a saxophone, and most importantly, turn blue trying to blow into the cylinder when both were closed. This thing may actually stand a chance of running after all!

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