>I'll give you all a hint, a $35 O2 sensor, the bung to be welded
>to the manifold and a digital voltmeter are all it really takes.
>There is a FAQ about this available from the fwd VW FAQ location
>(which I am not currently sure of the location).  I've personally
>been wondering how HALTECH and Berg can charge highway robbery
>prices for their little LED voltmeters.  In short it goes like
>this, the O2 sensor thread is same as 18mm sparkplug, you can
>get the bung from Parts Place or elsewhere or get a "spark plug
>no fouling" adapter from local parts store designed to keep
>plug OK in an oiling cylinder, the adapter is male thread one
>side, female on the other, grind off the male, drill a hole
>wherever (remember beyond the merger of the exhaust from each
>cylinder bank on a VW or before it if you want to tune each
>bank individually with 2 sensors) drill a hole and weld/braze
>her in.  Buy a generic heated (3 wire) sensor, around $30 even
>if you get a good deal, screw her in, appply 12V to heating leads
>look at the output with said meter, .45V is stoich, lower volts lean,
>higher means rich, two sensors are great for dual carbs.  Whole
>thing even if you buy a voltmeter should be less than $50.  Of course
>if you really must have a little LED display I can probably look
>in some old Radio electronics and find an article about building
>a little in line LED Voltmeter display for under $15.  BTW full
>instructions should be at lap.umd.edu in the vw_archives directory
>under ExhaustAnalyzer, ftp as anonymous login and you should be
>good, if anyone wants I will email you the full instructions if
>you don't have ftp capability.  Oh if you put 2 in close enough
>to the heads you probably don't even need the self heating style,
>you need it only if you are putting them far down line after the
>merger, check local speed shops for the bungs and plugs to replace
>the sensor if you don't want to leave it in, or if you only want
>to buy 1 sensor and tune 2 banks individually.  Thread is hypothetically
>18 x 0.5 mm but don't hold me to that.
>
>
>John Anderson (saving you money)
>ja@coe.wvu.edu
>'71 Westy, '90 Corrado G60

If you already have an accuraty volt meter this is fine.
Otherwise add another $250 or so for a quality DVM

Stephen
'75 bus