Hi everyone
I managed to carve out a little bit of time over the holidays to work on the Pacific. I didn’t get very much done but every little bit get me closer to the end.
There are a couple parts (safety devices) that go in the fuel inlet piping between the vapor carburetor and the engine. The first one is the flame arrester; this device has a stack of metal screens inside a housing that in the event of a backfire will quench and extinguish a flame that is moving back up the pipe.
The next piece is a check valve/ relief valve assembly that mounts directly on the vapor carburetor. In the event of a backfire the relief valve opens and vents the excess pressure which keeps it from trying to push back into the carburetor. Also contained in this assembly is a swing check valve that opens when the engine pulls vacuum to let fuel through and then seals when the vacuum is removed.
I started with the flame arrester and then will move onto the check valve assembly.
Below is the patent that I have been working from; you can see both of these parts in the drawing and how they are used.
The flame arrester was modeled in Geomagic; Using the existing piping and hand cocks as a guide I played with the size and shape until I came up with something I was pleased with.
Starting out the insides of both the top and bottom were machined; leaving the bottom half long for something to chuck on to.
The top was screwed onto the bottom and then faced to length.
Here the top section has been machined to length.
The stock won’t fit in a collet so the bottom was held in a 3 jaw chuck and also faced to length.
Both the top and bottom had the hex cut and the 1/16” NPT threads put in.
I used the step and cut method to generate the profile of the oval shape. One end was held using a ½” hex collet then when flipped around to profile the other end a round collet was used on one of the steps. This worked out better to maintain concentricity end to end.
After some hand work with files and sand paper here is the final shape.
I still need to punch out the stack of screens to fit inside but that will be done later.
Here it is installed on the engine; I’m pleased with how it looks and complements the other parts on the engine.
Remember a while back I posted some pictures in the Chatterbox section of a couple large Fairbanks Morse carburetors that I had machined from castings? Well these parts were machined from the chucking lugs that were removed from those two carburetor castings.
I have also made a good start on the check valve assembly and will hopefully have an update on it in the near future.
Thanks for checking in.
Dave