re O2 sensor in SPICA car

["Giller,Bruce C." <bgiller@domain.elided>]

Tim,
	I just did this on my '73 so that I could attach a Wes I. Dynograph to
the business end of the O2 sensor.  It too, has a 1-wire lead.  Wes I.
said to put the sensor just after the two down pipes meet and just
before the first muffler (option 2 in your list).  

	The best orientation of O2 sensor would be horizontal to the ground and
pointing toward the tranny.  To do this, you need to remove the metal
reinforcing web (goes from the muffler to the pipe) to gain access to
drill the hole and weld in the O2 bung.  I just cut two parallel lines
on both ends of the web and removed the center section.  I used a step
drill bit to make the correct hole (11/16"?) right along the muffler
seam, and welded the bung on (ground the seam down so that the bung fit
better).  

	Now for metal modification work.  Screw the O2 sensor in and then try
to place the removed section of webbing back on - doesn't fit since the
sensor gets in the way.  I cut a crescent-shaped notch from the webbing
to allow the sensor to stick out.  I made it big enough to allow a box
wrench to fit on the sensor.  Then I welded the webbing back on.

	I did this all on a brand new front muffler when it was off the car so
I can't speak for how hard it would be to do this whilst the muffler
remained on the car.  Or on a rusty muffler.

	Bruce 

	'86 Spider
	'73 GTV getting gussied up in the body shop


> I would like to put an O2 sensor in my '74 spider to aid in tuning air/fuel
> mixture. For convenience, I would like to use a 1-wire sensor. I took a look
> underneath and I'm not sure where would be the best place to mount the sensor.
> The car is still using the OEM 4:2 exhaust manifold.
> Some of my options seem to be:
> 1) in one of the two down pipes (only reading two cylinders)
> 2) right after the two down pipes come together but before the first muffler
> (very tight installation here)
> 3) after the first muffler (too far back?)
> 
> Any suggestions?
> 
> Tim Lentz
> Tampa, FL

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