I need to instal a second coolant temp sensor in the head. The new sensor is 3/8” NPT. My searching leads me to believe the mechanical sensor port on my 235 head is 5/8” straight thread. I’ve seen the available adapters to use that port. But that would leave me without a functional temp gauge.

Where in the head is there enough meat to drill and tap a new port?
I’d go to the T-stat housing but that’s not recommended in the efi instal directions.
Is there a mechanical gauge with an extra long thermocouple to reach the T-stat, that could be an option with Langdons housing.

Thanks

Pat
1940’s tech was great in the 40’s