Finally time to mount the battery tray to the firewall. I've agonized over this for a long time. I tried clamping the battery tray in place so I could match drill the three holes, but I decided that would be tricky to keep things from moving and wouldn't give me much control on the hole locations. And if the holes on the battery tray bracket moved, I would have to figure out how to move the nut plate. It finally dawned on me that I should enlarge the three rivet holes and then file the holes as needed to match the holes on the battery box. I enlarged the three rivet holes in the firewall with a step drill and/or a #12 angle drill. I used boelube as a cutting lubricant, but think my drill bit dulled quickly. I filed on one of the holes in the firewall and now everything matches. I need to install the nut plates and then adjust the holes in the firewall with a file if needed.

Now time to finish the battery tray assembly. I enlarged the screw holes slightly so they are clearance holes. I drilled and countersunk the nut plate holes. I primed all the bare metal. I bought black spray paint and painted the front of the battery tray. I left the inside and back of the battery tray with primer only in the areas I had touched up.

While waiting for primer to dry I started looking at the mounting for the master and starter contactors. I purchased these from B&C based on information from AeroElectric. I have been rethinking my decision to use the B&C starter contactor because:
1) Using a copper bus bar between the two contactors is much more difficult and the bar is more exposed to accidental contact than if I use the Van's style contactor.
2) I have to figure out mounting and a doubler instead of just using the Van's documentation.
3) A presentation at an EAA chapter 187 meeting that showed problems with an automotive solenoid that looked similar to the B&C contactor.
I decided to use the B&C master contactor and the Van's starter contactor because of items 1 and 2. I don't think item 3 applies because I believe the B&C contactor is a good design. FYI, I took the B&C starter apart on 10/7 and verified the inside is much different than the inside of the one shown in the chapter meeting.

I called TJ at B&C to ask a few questions about the starter contactor and realized I really didn't know anything about the starter that is on my engine or how that fits into the Van's wiring instructions and my schematic. I researched on Van's website, Sky-Tec's website and Van's Airforce. If found out the starter I probably have installed is a 149NL. If so, this is not a permanent magnet motor and I should use my schematic which closely matches the Van's and Aeroelectric schematics. I need to confirm which one I really have.