Exhaust 02 Bung

Locate a good mounting spot for the 02 bung, sometimes this is easier to do with the exhaust mounted on the car. Try to keep it behind the OEM 02 sensor and in a 10-2 O’clock orientation (top side) of the exhaust. Sometimes the heat shield will need to be trimmed so this will give you a better configuration where you want the 02 bung located.

Pull the exhaust off and bring it to a clean work bench.

With an abrasive pad, clean the location to where the 02 bung will be placed.

Measure out a 3/4" (0.7500”) circle with a sharpie. As you can see in figure 1, the ID of the bung is 0.6500” so making the circle 0.7500” will ensure your 02 sensor won’t touch the exhaust pipe.

Take a hole punch and punch an indent into the middle of the circle (0.375”) you drew with a sharpie. (Figure 3)

Cut the hole out, with a Unibit (step drill) or a 7/8" bit. Do NOT cut more than 7/8". Make sure you cut directly straight down.

Once the hole is complete, clean the top surface from debris and metal shards. You may need to use an abrasive pad. Blow out the inside of the exhaust with compressed air. (Figure 4).

Center the 02 bung over the 7/8" hole.

Tack weld (2) spots, cover the top of the bung with a plug or piece of wood to keep splatter out of the threads. Run a bead around the entire 02 bung. Make sure it has no leaks.

Reconnect the exhaust to the machine, trim the heat shield if need be.

Whether you are placing the block-plug or a 02 sensor into the bung, put anti-seize on the threads. Block off bolt is a 19mm, the 02 sensor is a 22mm. (Figure 5).