The Stovebolt Site Forums The Shop Area Engine Shop what temp is best in a 350?

I have a 190 degree thermostat in my 350. It stays there most of the time but will increase to 210 when 4 wheel drive and tooling around.

Just wondering the optimal operating temp? Is cooler better? What are the negatives of removing the thermostat? I live in Florida so it almost never gets cold.

removing the stat completely will result in overheating, although some folks take the center part out, leaving the surrounding "big washer" to maintain a flow restriction .... around 200 is good for a small block with a 14# cap on a rad that can take that pressure - slightly higher temps expected if you're working it harder

Bill

Do you have a fan shroud? That may help cool it when your working it. You could try a 180 state. How close is the fan blade to the radiator? If its to far away the fan could be not moving enough air.

With a 195 stat and a 14-17 lb. radiator cap the normal operating range will be from about 190 to 220 or so. That's what the engine was designed and clearanced to do. It won't even begin to boil any coolant until it reaches almost 250 if the radiator cap and hoses are in good condition. The only limiting factor will be your heater core, which was designed for a 7 lb. cap if you're talking about your 4X4 NAPCO.
Jerry

I've always had an understanding that 350s run a little hot 210-220 range.

I have an electric fan, and the engine never gets above 215 even on the hottest days in Florida, so it looks like I'm in the good range. I guess what seems hot to a human isn't so hot to a Chevy 350.

Out of curiosity, why would the engine overheat with the thermostat completely removed?

It won't unless there is another problem with the cooling system. Removing the thermostat will not fix any problem would be a better way to put it.

It will if you end up sitting in traffic. The water flow through the engine and radiator doesn't have a chance to cool since it is being constantly flushed through. While driving, this isn't as big of an issue as all the airflow pushed through the radiator helps. Sitting in traffic, you only have what the fan can pull through the radiator while the water is constantly flushing. Not enough.

I have never used anything above a 180 degree thermostat in a small block and have had no issues. Once I tried a 160 and the heater would not function due to the water temps. We do not have climactic extremes of heat or cold during the seasons here in the PNW, but I imagine you get fairly warm in summer.

Running without a thermostat decreases gas mileage a bit and can create issues tryng to warm up an engine.

Jeff

if the thermostat is completely removed, there is a problem with the system, the water flow is too fast to pick up enough heat from the engine and too fast to achieve the design cooling from the rad - things might work fine under some ambient temps and loading, but the Generals engineers had good reason to design the system as they did .... by removing just the thermostatic portion of the stat, the 'doughnut' left in place keeps a restriction to control the rate of flow to the original design, you just lose the precise control of temp range set by the stat rating .... and these engines do work best and last longest run at the design temps

Bill

The main concern with running without a thermostat isn't overheating, although the dwell time of the coolant in the radiator could be an issue. All engines are designed so the parts establish a correct running clearance at a particular temperature, and the 350 is designed to run around 200 degrees or hotter. I can usually spot an engine that's been run without a thermostat when I tear it down for a rebuild by looking for a thin shiny area in the middle of the piston skirt. An engine that has been run at the right temp will have a much wider piston-to-cylinder contact patch because the piston heats up and gets round at the proper operating temp. Bearing clearances also get right when the crankshaft and rods run at the correct temperature, and the rings expand to minimize blowby.
Jerry

Thanks, I definitely learned something new today. It makes perfect sense that the radiator wouldn't have enough time to cool the water.

175 thermostat and 14# cap. She runs at 190/205

Jerry, you are spot on. Thanks for the reminder!!