What is the normal operating temperature range for a 1976 Corvette with the standard 350 V8. Mine has run hot (220 - 230) ever since I have had it. I have replaced the thermostat with a 160 degree, took off the fan/clutch, and replaced with dual electrical fans - this help somewhat ut did not take care of the problem. I took out the electrical fans, and replace with a flex fan (not fan clutch - direct bolt on to water pump pulley - that but me back to where I started.

 

verify the temps with IR gun or something.
that is way too high.

if accurate, look for blown head gasket, blocked radiator, some thing

180-195 is ok

 

Normal should be around 180......

Mine on the other hand runs on the cold side. The only time she hits 180 is in mid summer. When it's cool out I'm in the 160-170 range. I even had to take out the 160 thermo & put in a 185. I couldn't get past 150 in the Fall otherwise........

 

Original 350 in my '76 ran about 200-205 after I recored the original rad to a 4 core BB. This was with a 180* thermostat and stock fan & shroud.

New, as of 2-3 years ago, 383 stroker with 180* thermostat, Permacool electric fan and no fan shroud, runs about 190-200*

 

My 76 runs consistently at or below 200.
However I did lose the two belts that power the water pump, fan, and alternator a few days ago and had to replace them on the side of the road. I just had a hunch something was wrong when it got to around 240.

 

If you verify that your gauge is correct. Either by installing another gauge that takes the factory system out of the loop. I use a racing gauge that requires no power. I remove the factory sender ( when the engine is cold)and install the racing temp gauge components. I do not mess with the gauge in the dash at this time. I run the engine and verify what it reading is like the factory. If it is not, than I check the sender and the gauge. If it is the same, running on the hot side, then I remove the radiator, (unless you KNOW it is in perfect condition, radiators start getting blockage from the bottom and work their way upwards, it is hard to tell by looking in the tank) and either replace it or have it checked out and have it re-cored.
Also the foam rubber seals that seal the radiator to the radiator support and the radiator support to the underside of the hood MUST be intact. This allows air to go through the core instead of around it due to being on a slant. Your lower air dam is important also, it should be on so more air can be scouped into the radiator core.
I myself would remove the 160 degree thermostat and replace it with a 195 degree. As I was told by a reputable radiator manufacturer. Thermostats BEGIN opening at the temperature that they are marked and WILL be totally open 15 degreees AFTER. SO a 160 degree thermostat is totally open at 175 degrees. A 195 degree thermostat is open totally at 210 degrees, which is an acceptable running temperature. You want to make the thermostat can cycle open and close so the water that is in the radiator has time to cool down before the thermostat opens again allowing the cooler water from the radiator to enter the engine and then the thermostat will close again so the hot water from the engine is now in the radiator being cooled. Repeating this cycle over and over. If your system is not correct, your are allowing the water to get hotter and hotter because it has no time to cool down, due to a plugged radiator, improper mix, leaks in the system, etc.
The C4 Corvettes use a 195 degree thermostats and they run fine even in the summer. But do what you feel you have to do. This is only my suggestions from real world experience.
MAKE sure that you have no leaks in the system by using a pressure tester and also check your cap. Test it to 15 psi. If you have a pressure tester, you can check for a blown head gasket by installing the tester and starting the engine. With the tester reading "0", and if you start the engine and the pressure starts to climb instantly, you have a blown head gasket allowing cylinder pressure to enter your coolant system.
Make sure that your coolant overflow bottle is in working condition and has coolant in it. When you fill up your radiator, ( even running with the thermostat open) the coolant system will take about another quart or so due to the air pockets that are in the system that will be drawn in from the coolant overflow bottle when the engine cools down.
You must also remember that other individuals on the forum that have cars operating correctly just like yours is hard to compare to. The type of oil he uses may be different... less friction. Their jetting of the fuel in the carb may be different... richer fuel aids in cooling the cylinders. They may have the ignition timing set different do to the type of fuel that they like to use. Compression ratio and ring drag on the cylinders. Excessive oil blow-by and crap build up on the engine block aiding in holding IN THE HEAT. There are so many variables to list that it is hard to say why if you had 20 Corvettes all the same year that they all are different in some way.
But if you get it to operate around town and it is at 210 degrees, I would not sweat it. Like I mentioned in another post. The electric cooling fans of a C4 come on at 226-228 degreees. I really start to worry when the coolant temperature get to 260 degrees, because that is slightly above the temperaute for the auxillary cooling fans on a C4.
Good luck and I hope you enjoy your ride.
"DUB"

 

180 to 200 degrees is ideal. Your operating temp directly impacts your oil temp which needs to be at 212~ to vaporize the liquid water from the oil. Liquid water is a byproduct of combustion and blowby and fouls the oil.

Typically, your oil temp will run 20-35 degrees hotter than your coolant temp. For this reason, oil temp gauges are a very worthwhile investment.

If your engine is running 200, 210, and hotter, it will cost you some HP.

FWIW

 

I had a similiar problem with my 69 and after replacing the thermostat which didn't help, I had some suggestions (I believe from one of these forums) to make sure all the air was being directed through the radiator. Low and behold after some sealing with gasket material around the shroud, it made a huge difference! Oh, I also put some "Royal Purple Ice" additive which claims to reduce surface tension and therefore cooling temps,,,,,might have some contaversery, but I was getting desperate,,,and appears to have at least helped!?

 

The '76 C3 engines had a 195F thermostat installed (if I remember correctly), so normal operating temps were around 200 degrees. You could change the stat to a 180F unit and the engine should operate close to that temp; that would be more desirable for the engine...but not for emissions. I suspect that your radiator needs to be cleaned (not just flushed out) to get rid of collected scale, etc. on the inside of the cooling fins. This is the #1 reason for poor radiator performance. Get a container of Prestone radiator cleaner and use it per the instructions. After cleaning and refilling with 50/50 mix of antifreeze/water, your engine should run much cooler. You might also want to check your lower radiator hose to verify that it is not collapsing under water pump suction forces (the steel reinforcement 'spring' inside the hose can rot away over time).