I'm putting an efi 5.0 with long tube hookers in my 65 comet, does it matter if I put the O2 sensor in the exhaust right behind the header or should I drill a hole close to where the tubes met up and weld on a nut on to screw the sensor into?
I just did some research on this and the common practice is having the o2 installed in the reducer bolted to the collectors.. You can buy reducers now with the o2 bung installed.
Also, I'm not sure if this is fact or fiction, but if the O2 sensors are used at the collector with long tubes, then you need to make sure the sensors are heated, or HO2 sensors. I think they all are now-a-days, but just something to keep in mind. Good luck with the swap!
You should mount the O2 as close to the engine and top of the pipe as possible. I have mine in the collectors and they are pointing at each other from left to right. I'm using a T4MO EECIV from a 95 mustang and I have the pulse length and warmup times changed to match the distance from the engine. The only problem I had without the tune was it would stall on a warm restart unless I held the idle up for about 20 seconds.
