FE Cooling issue

[RICK LAKE]

951Mat Here is some of the things to check. All these thing helped drop my coolant temps.
Start with the radiator, straight up and down help let the most air throught it without fan assistance. The more the angle the less the flow of air with out the fan running all the time. I have found that the splitter that ERA sell with the car work well. I like the look of the 2 small fans in the front but they don't do alot to move the air through the Radiator. They also block the air flow to the rad. Choice is yours on this.
Hoses, Are you running all rubber hose on the bottom line or steel with short turns. I have found that this hose will collapse when the motor is running if it doesn't have a wire support. Exhaust pipe works great for this run with just 2 short turns on the ends. Same applies for upper hose, more steel less rubber.
Pulleys, who's are you running??? If they are March, you will have a heating problem at Idle I went through the same problem of 215-225f at idle. March sells pulleys that slow down the speed of the water pump and Alt. This is the wrong way to go. You want to look at the custom Kirkham pulley set they sell. Water pump and crank shaft are the same size, look great and increase flow on the water pump. I would have to measure but 6" upper and lower are about the correct size.
Intake manifold gaskets and ports for coolant flow. Depending on who's manifold you are using, some need to have the grinder used to clean out the coolant passages. You can gasket match with the intake gasket and go in about 1" and clean out the scale. Becareful to not remove too much and cause a leak. Just good cleanup. Intake gaskets, if you are using the 1247 ones they slide down and partially block off the flow between heads and manifold. They should be RTV or High-Tac into the correct position on the intake manifold and allowed to dry before installing. This applies with the return on the oil from the heads too. Trim the gasket to make sure you get a clear return.
Thermo stats I use BB dodge RB motor ones and trim about 2mm off the outside edge. The hole is about a 1/2" larger than the FE one they sell. This means alot more flow through it. 2, 1/8" holes in the housing for air to get out on the motor. If you can find a garage with a vacuum coolant machine this works the best with removing the air and complete fill of coolant.
The last thing is getting a pressure gauge hooked to the coolant system, This is a long shot, a small leak of the headgasket. This would be the last thing to go through. This would be IF you have felpro 1020 gasket in the motor. Look for an funny looking crud on the inside of the valve covers, could be either side. AGAIN this would be last and sending out the heads for a pressure test.
The coolant mix has been talked about. I use 50/50% and 1 bottle of waterwetter.
Do you have the headers rapped or heat coatings on them? A big problem is getting the heat from under the hood area. I run to small fans that pull the heat from under the hood and go out the side vents in the fenders. Brings the temp down about 15-20 degrees.
Start with the thermostat going larger in flow and hoses and see what happens. I think with the thermostat, hoses and correct pulleys for speed of the water pump this should bring down your temps in the motor. Good luck Ps some of the guys park their cobra with the nose up on jack stand to help get all the air out of the coolant system and get a complete fill of coolant, it's a free trick. Rick l. Ps I have an Aluminum motor and went through all that is posted above to get my motor to idle in the 180's and race in the 205-210f range. I am also running a Griffen rad in my car after pulling the copper one from ERA. I was looking for lower readings too.