O2 sensors

[littlemanjoe]

In Stock Eliminator on a car running multiple carbs.
Can anyone shed light on running O2 sensors?
Are you running one in each collector or one in each header tube?

[Jim Caughlin]

For sure if you run sensors on primary tubes particularly on something dual plane, you are going to get readings all over the map. Doing the primaries is going to give you ideas about how bad the fuel distribution is but not really the best choice for overall jetting decisions. The collector is the best compromise and where most people run them. Make sure you locate them far enough upstream to not get readings from the open exhaust reversion.

Jim Caughlin
SS 6019

[Darcy Clarke]

As a guy that runs 3 multi-carburated cars I have found both on the dyno and on the track to truly tune you need one in each primary. The collector O2 work but is an average of 4 cylinders and you can still.be way off. If you do run 8 make sure you have lots of battery reserve!!

Darcy Clarke
6254
SS/EA A/SA

[Jim Caughlin]

Originally Posted by Darcy Clarke

As a guy that runs 3 multi-carburated cars I have found both on the dyno and on the track to truly tune you need one in each primary. The collector O2 work but is an average of 4 cylinders and you can still.be way off. If you do run 8 make sure you have lots of battery reserve!!

Darcy Clarke
6254
SS/EA A/SA

Yup, when I checked O2 on primaries, I have 2 lean cylinders and 2 rich cylinders so O2 on collector averages everything out and says things are OK. In a SS application, there is the ability to possibly modify the intake and improve the situation, a lot tougher in Stock but maybe some creative corner jetting might help?

[KRatcliff]

Originally Posted by Jim Caughlin

Yup, when I checked O2 on primaries, I have 2 lean cylinders and 2 rich cylinders so O2 on collector averages everything out and says things are OK. In a SS application, there is the ability to possibly modify the intake and improve the situation, a lot tougher in Stock but maybe some creative corner jetting might help?

You might also play with varying the plug heat ranges.

[littlemanjoe]

Originally Posted by Darcy Clarke

As a guy that runs 3 multi-carburated cars I have found both on the dyno and on the track to truly tune you need one in each primary. The collector O2 work but is an average of 4 cylinders and you can still.be way off. If you do run 8 make sure you have lots of battery reserve!!

Darcy Clarke
6254
SS/EA A/SA

Darcy, The car is running a 16 volt system with alternator. Is battery reserve still a concern?

[Jim Caughlin]

One other comment on O2 sensors, they don't like leaded fuels so accept that they don't last for long periods of time. There is no solution to this so just accept them as a disposable item.

[Darcy Clarke]

I run a 12 volt system and run 2 batteries do lots of reserve, not sure with 16 volt.

Yes on my stocker the max wedge intake presents the challenge, better tuners can figure ot out without but I chose to run 8 O2 sensors on the dyno and tuning was much easier and picked up good power.

Darcy Clarke
SS/EA A/SA

[btrc]

Originally Posted by Jim Caughlin

One other comment on O2 sensors, they don't like leaded fuels so accept that they don't last for long periods of time. There is no solution to this so just accept them as a disposable item.

What are the signs that the O2 sensors may be bad? I have a lot of runs on mine.