Drilling four holes seems like it should be easy, right? Hah! Apparently heat cycling the header a few times had already started to harden the stainless, making it really hard to drill.
Mario's welding is some of the best I've seen anywhere. The whole time he was welding these bungs he was complaining about how the 303 stainless alloy (a diagnosis he eyeballed) is hard to weld and how his welds were coming out terrible.
And then they looked like this. Yeah, they're awful Mario!
Keeping the wiring and plumbing clean on a swap like this is a challenge. Adding more sensors and more wires really threatens to turn the engine bay into a rat's nest, so I put some effort into making things clean. The 4-Channel UEGO Controller comes with this very clean harness on the left. The connectors for the Bosch LSU 4.2 UEGO sensors are huge, but still just barely small enough to fit through the A/C evaporator hole in the firewall.
To keep the wires tidy, I made this fancy pants bracket from the mis-sized spacer I removed from the bellhousing adaptor in the last installment. The Bosch connectors all have those annoying one-time Christmas Tree fasteners that let them mount to a simple 1/4″ hole in sheet metal, but flat refuse to be removed cleanly.
Nice and clean! Just ignore the spaghetti on the valve cover…