Q: I’m trying to control the coolant temperature in my project vehicle. It’s got a new Chevy 350 engine block with a high-flow water pump and thermostat, plus I’m running a 30” x 19” aluminum radiator that gets plenty of airflow. I have tried a couple of different setups but the coolant temperature always creeps up slowly.

I would like to know if a four-row copper and brass radiator would be more efficient than a two-row aluminum unit. Also, what’s the optimum operating temperature for a small block Chevy? Finally, where’s the best place to locate the temperature sender?

basic stock engine coolant water tempeature gauge in the dash of an old car
(Image/Jeff Smith)

A: Great questions.

Aluminum dissipates heat more efficiently than copper and brass, so it gets the job done with fewer rows of tubing. Plus, it’s lighter and that’s always an advantage when it comes to high performance.

An aluminum radiator with two rows of 1” tubing will provide cooling equivalent to four rows of copper tubing, and it should be sufficient to support up to 400 horsepower.

If your powerplant is pumping out more horses, you may need a radiator with two rows of 1¼” (up to 600 hp) or 1½” (up to 800 hp) aluminum tubing. As long as your ignition timing and fuel mixture are both correct, a properly sized radiator with an appropriate fan and shroud should keep things cool. A product like Red Line’s Water Wetter cooling system treatment may also be helpful because it can boost the cooling properties of water.

Ideally, your engine should operate at 180°F to make the most power. The temperature-sending unit can be located in the cylinder head or in the intake manifold.