In the continuing saga of building my first internal combustion engine, I posted last week about encountering a problem with making a spring and having it come out the right dimensions. I've managed to get past that roadblock by making yet another fixture and another spring.
The end result fit the previously made parts better than anything so far.
That's the intake valve assembly, with the spring retainer on top and a piece of temporary wire through the valve that holds it in place. The fixture is in front of them. I had a spring from an old project that was just about the ideal size for the exhaust valve and that one just needed to be cut to length.
Intake on the left, exhaust on the right.
The next puzzle was the exhaust pipe (since there's nothing in the pipe it seems wrong to call it a muffler, like I did before). The tricky problem here was cutting off a thin-walled (about 0.015" thick) piece of bronze pipe that I made by drilling a 0.344 hole into a 0.375 bar. Not just cutting it off; cutting it off at a 30 degree angle. Two problems stood out: the first would be holding the work at the proper angle, and the second would be holding the pipe tightly enough to withstand cutting forces while not crushing it.
My solution: make a fixture by drilling a 3/8" hole in a piece of 1x2 pine, 30 off vertical, slitting the piece of wood in half along the 2" dimension vertically, and then clamping the wood around the pipe. Move the combination onto the Sherline mill, clamp it in the vise and cut it off with a thin slitting saw. Like this (at setup):
You can see a wood screw at top left, one of two screws clamping the front and back pieces of wood down around the pipe. After lining up the edge for the cut this way, I moved the pipe to the left side of the saw blade (in this view) and made a cut. The blade was too high, so I lowered the saw blade about half its thickness and made the cut again. Closer, but still a bit short of the right depth. Lowering the blade one more time, got me the right cut.
What's left? I don't know. I've gone through the drawings a few times, and I think I've made everything that goes into the engine. If there are missing parts, they would probably show up best if I go through the box of completed parts and try to put it all together. I suspect I'll cut a handful of custom washers and spacers. I know I need a set of ignition points, which the plans call out as: (1969 DODGE CHARGER, 383, 4BL, W/SINGLE POINT DIST.) I have a couple of auto parts stores within a couple of miles of home. Time to go get those.