the Corsa was not available with an automatic transmission. In fact there was no room on the Corsa dash to fit the automatic gear selector, the tachometer occupied the space that the Monza selector fit in. I like the dash mounted shifter, only better on was the Chrysler "typewriter" but federal requirements eliminated that also. The other problem with the Corsa dash is that it required a part that is rapidly becoming unobtainable - a thermister that screwed into the cylinder head.

To get the automatic you were linited to either the base 500 or the Midline Monza, both of which came standard with a speedometer, gasoline guage, a space in the middle that said "you didn't buy the extra-cost clock", and a number of idiot lights.

Original Monza Cluster (Wood Wheel did not really fit image)

Now the space left by the unbought clock was actually filled by a removable insert (so the dealer could easily accessorize a car on the lot) and the insert is nearly four inches in diameter.

Monza "You didn't buy the Clock" Dash Insert

This provided a potential mount for any number of gauges however for my purposes, what was wanted was a temperature gauge, and more, one that could read as high as the Corvair unit, at least 600 degrees F.

Now a 600 degree temperature guage is not found at yout typical friendly local auto supply store however are in common use on aircooled ultralight aircraft. Soon I found that for less than the price of a thermister, not just a cylinder head temperature gauge, but a dual cylinder head temperature gauge complete with dual 14mm ring thermocouples was available (Westach 2DC8 with 712-4WK thermocouples). This is a two inch diameter guage and comes with a rear "U" mount ( http://www.westach.com/products.htm )

Aside: AC used an always-expensive thermister for the Corsa gauge because being a variable resistance device it allowed the same circuit AC had been using since the '30s for 6v & 12v gas and temperature gauges. A thermocouple OTOH is a voltage device and in this case produces 9.6 mv (.0096 v) at 400 degrees. An entirely different circuit is used but has the advantage of being independant of the 12v supply and working even when the engine is off and the key removed. A thermocouple does have the disadvantage of actually being the difference between the sensor and a reference point. For a 1200 degree reading this will not make a lot of difference however for temperature between 200 and 400 degrees there can be an induced error. For instance the typical reference point is 70F. If the reference point is at 100F, the meter will read 30F low. So when driving in the desert at 110 degrees, the meter will read 340F when the actual temperature is 380F. Worth knowing about.
See http://www.frostalarm.com/cat/dp53.html for a brief explination.

Using the drill press, a 2" hole drill, and very slow feed a nice hole was made in the insert and the guage fitted. An orientation flat on the top of the insert made alignment relatively easy. The enclosed short connecting lead was extended with a 2 pair 22 guage cable to reach from the engine compartment to the dashboard. The run was through the unused grommet hole on the drivers side of the shroud which I suspect is for a fuel reurn line not present on my car, alongside the starter and over the heater hose then through the body behind the rear seat, and under the driver's side sill rail and finally behind the driver's kickpanel to the dashboard

With the initial installation two problems became evident: first while the instrument panel lenses were conical to reduce glare, the flat surface of the gauge lens made it almost unreadable in daylight. Second, there was no provision for night-time illumination. This made it necessary to rethink. A call to Westach provided instructions for the lens removal (pry black cap away from white side until the glue seperates). The lens can then re removed and the cap reinstalled) and that a part number 186 lighting kit was needed which installs from the rear.

Lens removal was straightforward but the lighting kit installation needs some explination: just the single longer tube is used and it does not look like it goes quite all of the way in before the bulb strikes the black cap. Rather than force it I taped the bottom of the tube in place. Second the supplied green rubber cap for the bulb gives good illumination with almost the same tint as the speedo and gas guage. The leads were also too short to reach anything useful and had to be extended. For connections I used a ring connector on one of the two mounting screws for the insert and a splice connection on the grey wire to the shift quadrant bulb

The next issue was connection of the thermocouple rings to the engine. As mentioned these were supplied with 14mm ring connectors that fit over the end of a spark plug. I had ealrier strobed the Virtual Vairs list (http://www.virtualcorvairclub.com ) with the concensus that the #2 and #5 cylinders were most likely to drop seats so I decided to put the themocouples on these plugs. This seems odd since I would have expected the #1 and #6 to be the furthest from the primary carbs and run the leanest but went with the indicators.

At this point I had two possibilities for running the thermocouple leads. The easiest would have been to slit and drill a hole in two of the spark plug boots and run the line through there. I chose not to do this because each boot removal would put stress on the leads I really wanted to avoid. The method used was to nibble a small channel about 1/8" wide and 3/8" long in the shroud starting from the edge of the plug hole. This allowed a seperate grommet to be used for the thermocouple lead that is retained by the spark plug boot.

Thermocouple Connection

This left routing of the cables from the thermocouples to the cable. This would not normally be an issue however the output of a thermocouple is actually  the difference between the heat source (spark plug) and a reference point. For best accuracy the reference point should be close to 70 degrees and the four foot cables cannot be shortened. To accomplish this I bundled the cables at the rear of the engine then ran the bundle into the fresh air inlet at the rear of the engine compartment so the referenece points are kept closer to ambinent (which in Florida is usually within 20F of 70F.

Junction of Sensors and Body Cable Routed to Inlet Duct

CHT in Dash (I like this wheel better for styling but would prefer a 15" with 3" dish)

Perhaps in the future I may rethink the gauge and might go to a 3" triple gauge with Tach, CHT, and Oil Temperature and a 420F scale instead of 800 F but for now it works.