Hi everyone,
I haven’t fallen off the face of the earth; things have just been somewhat busy around here and it will probably continue through the spring. Here are some pictures of tidying up a few loose ends on the bottom end with regards to the timing parts.
You may have noticed in that last few pictures of my engine that the main bearing area had some pretty sharp corners. This was because I needed to remove some material from the casting to shift the crossover cam closer to the center line of the engine. I spend a good part of a morning filling and blending in this area.
The crossover cam was also substantially trimmed to get things to come out to my liking. I will go over that later. Hopefully within the next couple of days.
One other thing I didn't cover was when I had the body set up in the mill to fit the upper swing arm bracket; I took a cut across the bottom surface of the bosses as there was quite a bit of extra material in this area. This required some filling and blending to match the machined surfaces with the casting.
Here is the body after some hand work; notice the top and bottom surfaces on the bosses are now parallel.
This picture shows the fit of the upper swing arm bracket on the bosses.
Here are some shots of the lift cam machining. I made a couple of extras one for my friend who is working on his Pacific and one more just in-case.
Staring out the stock is faced.
Then Drilled.
And bored to size.
Then set up in the mill in a V block and indicated in.
Both directions.
The mounting holes are spotted and drilled.
Then the profile machined.
Ready to go back in the lathe.
The Cams are parted off to the proper length
Here are the finished cams.
Next is the machining of the cap for the exhaust valve; not a major accomplishment but one more little piece. I deviated somewhat from the plans (do we see a pattern here?). I have seen some photos of a Pacific engine (maybe it was a Union or Regan as there all related) that had a pleasing dome shape on the top as well as the outer rim of the flange having a nice radius. The flange also overhung the boss on the valve chest slightly. So this is how I decide to make mine.
Starting with a piece of 660 bearing bronze (I like the color) it was faced and turned.
Then single point threaded 9/16"-18 to match the valve chest.
The radius on the rim was hand filed, sanded and polished.
Flipped around the stock is brought to length.
I had calculated all the points in my CAD program and a step over and cut approach was used to form the dome.
Here you can see the small lines that need to be sanded out to fully define the shape.
Here it is after some blending ready to cut the hex.
Set up in the mill and indicated in.
The hex is cut.
Then returned to the lathe to put the 15 deg. bevel on the hex.
Here it is installed on the valve chest; now I need to make the copper sealing washer to go under it.
Thanks for checking in,
Dave