I just got my first Samurai, it is an 86 in good shape. Only It does not have an O2 sensor on it. The previous owner put a weber carb on it and hedman header with 2 1/4 pipes. Lift kit.... Do I need to install an O2 sensor?? I am going to have to drop the exhaust system anyway to fix some bad welds... Also there was three bolts missing on the header! I got 22 mpg around town.

Thanks, carl

I guess the o2 sensor is only needed for fuel injection? Right?

Header bolt..the reason why it is missing is the bolt hole does not line up. Should I pull the header and drill the hole bigger? It does not look like there would be enough play in the other holes to bring it into alignment if I loosened all the bolts . Pretty poor installation, guess the guy got tired of throwing money at it.
 
Carl

Most aftermarket headers have a hole to put the O2 sensor in and I know the ECM uses it to make decisions about fuel and air to the factory carb. I don't think you need it for a weber as I haven't seen anything on one it could affect. I have put webers on 3 Samis and never used the O2 sensor in the process. Some of the tech guys on here may enlighten both of us on this mater.

I would remove the header and use a factory exhaust mani gasket as a template to open up the bolt holes required to get a proper fit and make sure the exhaust ports and header runners are perfectly lined up.

General info : back in ths era there were "feedback" carburators . They did use a o2 sensor  for on the fly adjustments in most cases these  systems also controlled ignition timing.

If your distribute has a vacume and mechanical advance there is no reason to have an o2 sensor. If it doesn't have the vacuum/mech advance I would find one that does. And completely eliminate the system.
Good advice on the header bolts. I'm going to add that all the bolts should be started and in a few turns before you tighten down any of them. Sorry if you already know this but I just wanted to mention it ...... Just Incase.

Yep the distributor has the vacuum advance so I am good to go. Any advice on it being hard to start when cold outside. This thing is really cold blooded! It has a manual choke. Once warm it runs great.