I have a 73 2.0, stock injection. Recently installed a brand-new combo gauge from PA Speedo. I presumed the oil temp gauge was calibrated to the sensor, but now I'm not sure. I installed a dipstick thermometer from Mainley Custom that I verified calibration against two thermometers at three different temps. My dash gauge reads 240 while my dipstick gauge reads 225. Would there be any good reason to see this kind of difference, or is my dash gauge just not calibrated correctly.

Normally a '73 2 Liter would have the center console temperature gauge. There were 3 different temperature senders used on the '73/'74 and later 914's. (200C sender, 120C sender and the 150C sender) If you remember, the center console gauge in 1974 and later was different than the 1973 gauge. It is possible that the sender in your car isn't the correct one for the dash combination gauge you installed. 240 degrees sounds way too hot.

I hover between 180 and 220. I get nervous when it gets higher than that...

the gages measure at differnt locations and the dip stick has some air around the top. Seems like a lot of a drop but it may be possible that the different locations and that the dipstick is not totally covered may affect the temps that much. Your reading both seem kind of high.

If you can pull the sender and heat it in water with it connected to the gauge....212F is the boiling temp of water.