re: Advice on installation of O2 sensor on 73 115?

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

Kevin,
	I recently installed a single wire O2 sensor in the stock exhaust of my
GTV to be used with a Dynograph to tune my Spica pump after an engine
rebuild.  Wes I. included the instructions after I bought the O2 sensor,
the sensor bung and the Dynograph from him.

	The instructions said to put the sensor as close as possible to where
the 4 down pipes meet and before the first muffler.  The sensor goes
parallel to the ground and "points" toward the tranny.  This required me
to cut off a reinforcing web on the muffler to gain access for me to
drill the muffler.  I drilled the hole with a step drill (can't remember
the size but I still have the instructions at home), welded the bung to
the muffler and then welded the reinforcing web back on.  I did put a
notch in the reinforcing web so that I could get a socket on the O2
sensor for any R&R I might have to do in the future.  I did all this
work with the brand new muffler on the garage floor.  So far, I've left
the O2 sensor in place but the Dynograph has been removed after I
adjusted the Spica pump (a Wes I. hi-performance model).  Since Wes I.
sent me a single wire sensor, I don't think that you need a 3 wire job.  

	It wasn't very hard to install the bung and besides I sorta like
cutting metal and then welding it back together.  It helped with fine
tuning my pump with pinpoint accuracy but I'm not sure that would have
been able to tell the difference been setting the pump by ear or by the
D'graph.  But it was fun and not very difficult.

	Bruce

	'86 Spider
	'73 GTV

> I want to install an O2 sensor on a Spica injected '73 Berlina so I can use 
> a Dynograph to fine tune the mixture after my soon-to-be completed  engine 
> rebuild.  My intent is to use the Dynograph as a diagnostic tool, not for 
> on-going use, and will eventually want to install a "bung" on the exhausts 
> of all my 105/115 alfas as the opportunities arise.  When not in diagnostic 
> mode, I'll want to remove the O2 sensor and cap the bung without leaks.
> 
> It is my understanding that to work properly, I'll need to install the O2 
> sensor before the front muffler, which leaves only one of the two head 
> pipes (1-4 or 2-3) behind the stock exhaust headers.  Finally, I understand 
> that I should use a 3-wire sensor with a preheater.   Any other suggestions?
> 
> Anyone out there done this?  Have any advice?  Is it worth doing??  Is 
> there a cap or plug to block the O2 sensor bung when the system is not in 
> use?  Has anyone tuned a 4cyl with Webers using the dynograph as feedback 
> on mixture?  How should it be wired?  Thanks!!
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