Miller Overhead Wrap-Up

Hardened rollers and shafts

Hi All...if you recall my last post, I had to finish up a few things on the overhead.  Specifically, the rollers and their shafts.  I finished making them a couple weeks ago, just had to heat-treat.  I made them from A-2 tool steel, which requires an air quench instead of oil or water.  Nice stuff to work with and machine.  I wanted them about 56 Rockwell C, which required a heat soak at 1450 F, then 1725 F, followed by a tempering at 900 degrees.  I'm not completely sure this is the hardness I want, but I'll watch them and see how they, and the valve stems wear.  They are easy to make if I have to redo them sometime.

 In the following pictures, you can see everything installed with the intake and exhaust valves properly adjusted at .010".  You can also see the grease zerk, not found on the stock overhead, that allows the valve train to be lubed - except the roller, it still has to be manually oiled.

So now, I'm going to start closing up the gear end of the engine.  The water pump, carb, etc. can then be installed.

Got back on the airframe a little bit too.  I had fit up the fuel tank a couple months ago, and had some hope that I was going to be able to use it after a good cleaning.  Well, looking inside with a borescope revealed mice had made a home in there for many years.  I think everyone has a good idea what mouse pee does to metal - not good!  I guess it was wishful thinking anyway, that a nearly 90-year old tank would be useable!

The tank is galvanized steel with soldered seams.  My friend, Mark helped me unsolder the old tank and flatten the sheets for a pattern.  We then cut out new pieces from 22ga. galvanized steel.  The tank has a rolled seam around the perimeter that is soldered.  All the pieces are cut out, just have to run them thru the bead roller to form the seams, and solder it all together.  Sounds easy, but not really.  Manipulating this large, 40 gallon tank will definitely be a 2-man job!

Original fuel tank skins

So my next post should have a completed fuel tank...if all goes well.