You DO NOT want a temperature gauge for an air cooled engine. They are calibrated much differently. Also do not differentiate between "block temperature" and "water temperature" gauges because they are calibrated the same. Block (or head) temperature gauges are "contact" type which merely means they measure the temperature of the head near the spark plug on a two stroke engine. Once the engine warms up both the water and head temperature will be the same. The other type of sender screws into a port in the water jacket. Again - no difference in temperatures. Four stroke engines need a water jacket type of sender because the area around the plug is not flat like a two stroke. You also cannot use an automotive temp gauge as the senders are calibrated differently. You can get what you need right here on iBoats. Click the SHOP button at the top of the page.
Go with what Silvertip says. He is an expert that has been around forever.
However, temperature is temperature. F* or C*. Only where and how you measure it varies. The outside of my kneecap is not the same temp as under my tongue. Temperature is knowing a baseline, like the human body. It's the variance from the baseline that warants further investigation.
It's kind of like a water pressure guage. It's the variance from the initial baseline that should catch your attention.
