Contrary to overheating, my 1968 302 Ford is running on the cool side(170) down the road. It's in a 1934 Ford with aluminium radiator with shroud. No heater core and using bypass hose from thermo housing to water pump with the other tube plugged. Sound I restrict the bypass hose a little and see if it makes a difference? If I let it idle in barn it will go above 180 .
What temp thermostat do you have? and have you checked it for proper operation with a pan of hot water on the stove, and a thermometer?
Restricting the bypass hose, likely won't make much of a difference. 170 is where everything is in equilibrium at that given ambient air temp. I.E. The radiator is rejecting the same amount of heat energy to the air that the engine is creating and adding to the coolant. There are only a few things you can do in increase the temp. 1: Put a higher temp thermostat in. This will likely cause the coolant temp to cycle up and down as the thermostat will likely not stay open all the time, but will open and close as needed. This happens in my '51 F-1 as I have a efficient, large 4 core brass and copper rad. Driving down the highway on a cool evening or morning, the coolant temp will cycle between 140 and 190, as the thermostat opens and closes. 2: Restrict air flow through the rad. By reducing the mass air flow rate through the rad, the coolant temperature will have to rise accordingly in order to maintain the same heat rejection rate as before. The bad part is you need to maximize air flow during idling and high traffic, so this can be a bit tricky. AC condensers and Intercoolers work well for this task. 3: Increase your engines horsepower. Ah, the Hot Rodders answer. Putting more heat into the coolant is always a good way to heat it up. Problem is, that it takes a certain amount of power to move the car along at 65 mph, no matters what. So whether you have 100 hp or 500 Hp under the hood, cruising at 65 will still produce the same amount of heat energy and the coolant temp will stay the same during those events.
4: live with it. It won't wear out real fast at 170, so if you plan to put less than 50k or so miles on it, you're probably not losing anything with the coolness. And it probably helps prevent fuel boiling issues, too.
Is it possible that you have a 160° thermostat in there????? We used those in our fox bodied cars for more horsepower..... Don't ask.....
I would say that your radiator is too good, your water pump is in excellent shape, the water jackets in your block and heads are too clean, and your fan is doing a great job. Mess one of those up and maybe it'll start overheating.
Whatever temp my hot rods run at without spitting coolant on the ground is just fine with me. If it’s not broken, don’t fix it.
I run mine with no fan at all. 160 t stat. It shows 145 degrees at t stat housing and 175 degrees at the head. I have no hood, no shroud ,aluminum heads and radiator. Been driving it for 16000 miles no problems. People ask how I run with no fan and can't believe it when I tell them it runs cool.