Worked on running the ECU bus, a large wire bundle, from the engine, through the firewall to the ECU. Last session I had drilled out a 2" hole to accommodate the ECU cannon plug diameter. Today I closed up the hole with the ECU bus running through a much small opening.
I began by wrapping the wire bundle with high-heat protective tape to help avoid chafing where it passes through the firewall. Next, I attached a firewall penetration (2 halves of a Zenith-provided steel circle with a 3/4" hole in the middle) to the firewall. This was accomplished by surrounding the ECU bus with the two halves of the circle and connecting the two halves to each other with clecos through pre-drilled holes. I then lined up the penetration so that it held the wire bundle in the center of the larger opening I had previously drilled out.
Once held in position, I drilled through the pre-drilled holes in the penetration into the firewall and attached the circle to the firewall using clecos. I then split a Zenith-provided nylon grommet, wrapped it around the bus, then fed it into the small circle in the firewall penetration as one final measure of protection for the ECU bus.
I also assembled a couple of "double adel clamps" to the upper left engine mount to secure the ECU bus wire bundle between its engine attach point and the firewall penetration.
Two halves of the firewall penetration connected around wire bundle during initial fitting.
ECU bus secured with double adel clamps running above the engine mount.
ECU bus running along engine mount to drilled out firewall penetration.
