O2 bung question
- Thread starter Heard
- Start date
glennpm
Well-known member
IMPORTANT INSTALLATION NOTE - UEGO Sensor Mounting Orientation
A weld-in M18 X 1.5 boss is supplied for sensor installation. Mount the O2 sensor in the
exhaust system at least 18 inches downstream from the exhaust port. If you anticipate high EGT's (over 800C), run a turbocharger, run at high RPM for extended periods of time or plan on running leaded race fuel then you must mount the sensor at least 36 inches or more downstream of the exhaust port as all of these can cause the sensor to overheat.
To prevent collection of liquids between the sensor housing and sensor element during the cold start phase, the installation angle should be inclined at least 10° from horizontal with the electrical connection upwards,
see below. (Figure 8)
Figure 8. Minimum mounting angle for the UEGO Sensor
You may want to put in bungs on both left and right side banks.
A weld-in M18 X 1.5 boss is supplied for sensor installation. Mount the O2 sensor in the
exhaust system at least 18 inches downstream from the exhaust port. If you anticipate high EGT's (over 800C), run a turbocharger, run at high RPM for extended periods of time or plan on running leaded race fuel then you must mount the sensor at least 36 inches or more downstream of the exhaust port as all of these can cause the sensor to overheat.
To prevent collection of liquids between the sensor housing and sensor element during the cold start phase, the installation angle should be inclined at least 10° from horizontal with the electrical connection upwards,
see below. (Figure 8)
Figure 8. Minimum mounting angle for the UEGO Sensor
You may want to put in bungs on both left and right side banks.
Last edited:
Seth Swoboda
Well-known member
Michael at Third Gen has tuned using an AF Meter. It goes in before the muffler on the Y pipe or header pipe.
Bored&Stroked
Well-known member
It can go anyplace downstream of the engine - usually a couple feet back from the block or head. On a flathead, your "ports" are already like headers, so I put mine back from where the rear port tube enters the main tube - about 6 - 8" back. I like to have the bungs before any header gasket or potential leak areas.
One thing that is very important is that you have NO exhaust leaks ahead of the O2 sensor (or the readings will be wrong).
If you're welding up headers for an OHV setup, I'd put mine in the collector area (at a 10 or 2 o-clock angle). Also, if you're making headers, consider putting some EGT bungs up by the block - as close as possible. In tuning, it is nice to be able to see the EGT temps and the O2 readings. If you can only find space for a single EGT bung, put it on the rear cylinder (which tends to run the hottest). If on a flathead, I put an EGT bung in the center port tube and the rear port tube.
I'd always put the bungs in both sides of the engine - in case you need to test/tune or compare one side to the other.
One thing that is very important is that you have NO exhaust leaks ahead of the O2 sensor (or the readings will be wrong).
If you're welding up headers for an OHV setup, I'd put mine in the collector area (at a 10 or 2 o-clock angle). Also, if you're making headers, consider putting some EGT bungs up by the block - as close as possible. In tuning, it is nice to be able to see the EGT temps and the O2 readings. If you can only find space for a single EGT bung, put it on the rear cylinder (which tends to run the hottest). If on a flathead, I put an EGT bung in the center port tube and the rear port tube.
I'd always put the bungs in both sides of the engine - in case you need to test/tune or compare one side to the other.