Before doing much more that might complicate its installation, I added the drip pan originalły planned for the stand underneath the engine. A box brake was used to form a shallow five-sided tray from 16 gauge steel, and its corners were tig-welded closed. After painting the tray with Rustoleum texture paint, it was attached to the cross supports on the floor of the stand. I've used this particular paint in model engine builds before (most recently, the Merlin's rotisserie assembly stand) because it's inexpensive and resistant to most engine fluids after being allowed to air dry for three or four days. The 'multicolor' version easily covers up significant surface defects (ugly welds, deep scratches, panel beating marks, etc.) with a thick, durable, and remarkably uniform looking finish.
I also finally completed the coolant loop between the radiator and the return inlets on the coolant reservoir. Even after a lot of thought, I wasn't able to come up with a drain **** that looked at home under the engine, and so I scrapped the idea completely. Instead, I'll just disconnect the return hoses from the coolant reservoir when the system needs to be drained. I machined three sets of spreader bars for the hoses, though, in order to tidy up their routing.
For completeness, I finished up the wiring for the electric starter even though all the work that I've put into the engine's starting system may have been for naught. John Ramm (the only builder I'm aware of to get a running engine completed from these castings) recently informed me that the steel bevel gears in his Merlin's starting system had a very short life that seemed to come to an abrupt end just after his engine's rings seated and cylinder pressures rose. This is why you'll see him slap-starting the prop in his Youtube video. I've had major misgivings about the robustness of the starting system design ever since coming to grips with the incredible complexity inside the wheel case. I took great pains in setting up the starter gears during the wheel case construction, and my modifications to the geometry of the cylinders effectively lowered the static compression ratio about a point and a half. I guess my starter's durability remains to be seen.
I mounted the starter components on a hand-formed sheet metal panel mounted to the starboard side of the engine just below the starter motor. Ten gage 'noodle' wire was used for the high current wiring. 'Noodle' wire is something I recently discovered in a local hobby store. It's an ultra-flexible silicone insulated wire, and in this particular gage it has an impressive 1050 strand count. For the starter solenoid I used a 120 amp SPST automotive accessory relay that I found in a local auto supply store. The starter switch is a red-cover momentary toggle reminiscent of the P-51's original starter switch.
A pair of 6 mm hex binding posts for the 12 volt battery input were mounted in a terminal block machined from black Delrin. Both the starter motor and the rear electrical panel will receive their power from these posts. Hopefully, the short term current carrying capability of these posts and their associated wiring will be adequate to handle the engine's 80 amp starting current requirement. Troughs were milled into rear of the block to accommodate the huge wire. Metal inserts were pressed into the block's machined barrier terminals to handle the connections running off the starter panel.
The starter panel was designed to be a standalone sub-assembly. The 12 volt power cable from the radiator fans was terminated on the starter panel but will be continued to a control switch that will be mounted on the electrical panel at the rear of the stand. The fan cable as well as the 12 volt power feed for the electrical panel will continue from the terminal block to the electrical panel through quick connect blade terminals on its rear side.
The remainder of the noodle wire was used to make up a pair of battery cables. Since I had taken liberties with the current carrying capabilities of several of the starter components, I energized the starter motor several times while checking the various connections for excessive temperature rises.
The next step will be to finish up the rear electrical panel. - Terry