I need to start cutting holes in my instrument panel soon, so I've been messing around trying to finalize the design. I need to start running the wires for the engine instruments, but I can't do that until I get the instruments in the panel. I know where the engine instruments will be, within about an inch. I decided to cut some holes in a plywood mock-up to hold the engine instruments until I nail down exactly where they need to go. That last inch I need to sort out won't affect the wiring, so this will let me make progress. I can't really nail down the exact location of everything until I get the racks that my avionics will mount in. I'm trying to push everything as far left as I can, and the fit of the racks will determine where the rest of the stuff ends up.

This week I installed the exhaust gas temperature (EGT) probes. It took a lot of measuring to figure out where to mount the probes. They all should be the same distance from the end of the exhaust pipe, not on a curve, and not on a weld. Of course every pipe has its curves and welds in a different place, so it was a real trick to find a suitable location. I finally settled on a distance of 4 13/16 from the end. Then I had to sort out what angle to have the probes come out, so they wouldn't hit anything, or get in the way of changing spark plugs. I really gritted my teeth when I drilled the holes, because the exhaust system is pretty expensive, but it all worked out OK.

Yesterday I drilled all the holes and installed the platenuts for the various stainless steel shields that protect the rubber grommets where cables, wires, etc come through the firewall. Today I ran the cylinder head temperature and EGT wires from the EIS-4000 engine monitor though the firewall, and connected them up to the probes. I used a heat gun on each probe to make sure it worked, and that I had it wired to the correct cylinder. So far , so good.