A New Idea for a Model A Temperature Gauge

[Tom Wesenberg]

Back in the 70's I saw temp gauges for snowmobiles, that used a ring that fit under the spark plug. I thought that was a great idea, and easy to install without any holes to drill or any other modifications. Last year my neighbor installed a similar one on his 1950 Morris Minor. I've never seen such a gauge with a ring probe large enough to fit the Model A spark plug, but I wonder how well it would work mounted on the head stud that holds the cable clamp?

If that doesn't work, then someone needs to invent a magnetic probe that could be attached to the rear cylinder.

[Rowdy]

Dakota Digital makes a large enough ring for the Model A spark plug. They are also quite common in aviation applications. Rod

[Mitch]

Would your readings be the same as an immersible probe or would you have to deviate

[Rowdy]

It would be CHT(cylender head temp). Should be near the same as immersable probe in the upper neck. I would recomend using #3 spark plug. Rod

[Rowdy]

Just had a look and Dakota Digital no longer has them listed. Aircraft Spruce has the ring with wire (type J) listed for $16.99. Not sure what the gauge would cost. Also you can not alter the wire length and have an accurate gauge reading. Rod

[Rowdy]

Keep in mind most Lycoming air cooled engines have a target CHT of near 380°F and a max CHT around 400°F. Controlling the A/F mixture has the most effect on CHT. If the engine is running rich the temp will be cool and if lean CHT will be higher. So even if not the same as coolant temp, it may help you to better control mixture and spark advance. Rod