Thread: 331 hemi from a new Yorker what temp is safe

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There is a temperature gauge quirk that both my HEMIs have. It has to do with running a mechanical gauge and the location that I use to screw the end of the pickup in (the crossover pipe that connects the 2 cylinder heads where the thermostat is located).



At above 2000 RPM or so the gauge will show 5-7 degrees hotter than the engine is actually running. You can actually watch the needle jump if you quickly step on or let off of the gas.

As near as I can figure this is where you have the 2 streams of water colliding and possibly the highest pressure in the system. I think what is happening is when the engine is reved that the pressure is slightly compressing the liquid filled bulb causing the spike in the gauge.

I've mentioned this before............I bought one of those Mr Gasket radiator caps with the thermometer in it and it is super accurate. My dash gauge is 20 degrees too hot, but when I shoot the engine with my infared gun it is exactly the same as the radiator cap reading. So I just ignore my dash gauge these days. I would strongly recommend one of the Mr Gasket caps to anyone who is questioning their operating temp.

Don