>
> In message <94May23.075219pdt.14532(8)@alpha.xerox.com> Jerry writes:
> > Sears used to sell a exhaust analyzer that worked off of 12V. I don't
> > know how well these worked, but just imagine driving along with a
> > constant reading of mixture strength!
>
>
> K&N makes a fuel/air ratio monitor. It uses an oxygen sensor, so you can't
> use it with leaded fuel (at least not for long!)
>
> Pegasus Racing carries then. THe instrument is $150 for a rectangular unit,
> and $163 for a round in-dash one. That includes the sensor and the fitting
> you weld to the exhaust manifold.
>
> It's on my list of toys for Sybil, but below new paint and interior...
>
> --berry
$150? Geeez, make your own. Parts needed:
1 anti-oil-fouler spark plug space for an old Ford (18mm plug). About $3
1 Universal single wire O2 sensor. About $30
1 analog or bargraph volt meter with a 2 volt (or so) scale. Digital
will work, but hard to read, and sluggish. price varies
Take the anti-fouler, cut the closed end off, and fish-mouth the cut end
to fit against your exhaust pipe. Pick an accessable spot on your header
pipe that sees exhaust from all cylinders, but is as close to the engine
as possible. Drill a 1/2" hole, and braze the fitting in place. install
O2 sensor. Run a single wire from the sensor to where the volt meter will
be.
This style O2 sensor, as used in the K&N kit and early Bosch injection
systems, puts out right at 1 volt when way rich, and 0 volts when really
lean. Things are pretty much linear. Calibrate your volt meter accordingly.
These sensors have to be over 600 degrees F to function properly. Below
about 400 degrees, they don't function at all. This is why you want it as
close to the engine as possible, and why all testing should be done dynamicly.
There just isn't enough exhaust flow at idle to keep it warm.
Okay, that's the basics. Would one of the E.E's on the list care to cook up
a 1 volt bargraph display using $5 of parts from your local Rat Shack? :>
Randy
randy@taylor.wyvern.com
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