Hot instruments? (337B)
 

I noticed my instruments (eng temp, fuel, oil press, aux fuel, oil temp, electrical) on copilot side are getting pretty warm, i would say 120F or so.

Defroster scat tube is not disconnected, there is also a 1” scat tube pointed at the back of these instruments.

It has been very hot here lately 90F+ oat.

Is this normal?

Yep, the instrument cluster was AD'd for additional cooling. Might want to check to make sure there is air being blown on them. Scat tubing tends to get broken and old, might need to be replaced or connected to the firewall

Cooling
 

Herb is correct about AD modification. The cooling air from the ports on side of fuselage cools your avionics, And on left side there should be a small ‘y’ that takes air from that cooling line and takes air up to gauges. I have installed an instrument cooling fan and run a dedicated hose just to those engine gauges.
Jeff