Whats the best thermostat temp to keep my bronco running in the 180-190 range.
What they said.
While ultimately keeping it in the 180-190 range may best be accomplished with a 180 (or not...) t-stat, it sounds like you're already running higher than the t-stat rating in your engine. So also as said, you have other issues.
But going straight to a 195 is likely your best bet for now, if your engine is finely tuned. What are you running now? Carburetor or EFI? What ignition and what is your initial timing, and advance curve set to?
What about the rest? Rebuilt or original? Camshaft change or not?
You should verify your ignition timing is not too low, and you may need to be using a mechanical fan after all.
If a carburetor and standard tuning, you may very well end up back at a 180. But don't go all the way to a 160 again because it causes more trouble than it solves. And since it did not solve it the way it is now, it's not going to next time either. Our engines prefer 180 or more t-stats when running properly.
With EFI 195 is your only real choice. The only modern cars I can think of that run cooler stats are those with engines like the Hellcats, Demons, COPO's and maybe a few others.
And engine that has a good combustion process and does not ping early will actually appreciate those 200° temps.
You're not overheating until your (accurate) gauge reads 230 and climbing. Of course, you don't really want it getting into that area because there's no more headroom. But at 210-220 if it's not climbing, you're still ok.
I went to a car show this morning and was at 185 on the way there when it was 75 out. I hit 205 today cruising at 65 when it was 87° out on the way out. Its only going to get hotter out.
How does it run around town at slow speeds? Sounds like aero and airflow could be your issue because it's running to much higher than the rating of the thermostat at higher road speeds.
Cooling setup is 160° tstat, aluminum radiator, flexalite electric cooling fan, 95 Mustang Cobra water pump, green coolant with royal purple purple ice additive.
The radiator should have more than enough capacity on it's own, assuming good flow through it.
The pump should be fine, though I don't know the specifics of a Cobra pump. Higher volume and pressure are good things for a pump to do, but even a stock garden variety pump is enough to cool a Bronco when everything else is working as it should.
Coolant type and additive are good. But what is your ratio? The more water, the better it cools, but we're not talking about enough to change the whole setup if you're just a little over 50/50 mix. If you're running mostly anti-freeze though, I would give it a little better chance by adding some water.
I never had a problem with "mostly" anti-freeze, but I always added just water when it was low. By the time it was time to change out the coolant, I was probably at a better than 70 percent water solution.
Not quite as consistently hot as your area, but hot enough to highlight issues if they were there.
Your fan choice could be an issue.
How big is it, what type is it, and how much CFM? Is it a puller or a pusher? Fully shrouded, or at least ducted?
An electric fan can cool a Bronco, as long as everything else is sorted. They really shine at slow speeds, but can also really struggle at higher vehicle speeds as aero becomes more of a problem than a help.
So what's your setup? Lifted? That makes the aero equation even worse.
Got pics?
I was turning around 2100 rpm on the highway for 20 mins
So what's your setup totally? Lifted? Big tires? What gearing? Overdrive trans?
Reason I ask is that 2100 rpm at highway speeds is pretty low for a Bronco, so that means you either have an overdrive, taller gears, smaller tires, or your highway speeds were not that high overall.
But if the gearing is wrong for the tire size, your engine will be struggling. And the harder the engine has to work at lower rpm, especially at higher vehicle speeds were air is trying to bypass and push back through the radiator, an electric fan is going to be fighting an uphill battle. And a Bronco is going to run hot.
Good luck.
Paul
