well I put a mech. temp gauge in the intake, next to the thermostast. s& left the elec. temp sending unit in the head.
as I have stated it it a bbc 454

at idle after 15min. 800 rmp.

electric in head reads ...225 and holds there
mech. in intake reads ... 155 after thermostat opens at 180, close until it gets to 180 again then drops back to 155

at 60mph after 15min warm up.

elec. reads 225 & holds
mech. reads 160 and never got to 180 until a stopped & idled for a min. then back down to 155

does this sound like a acceptable heat range for the motor?