engine running temp.

[55mike]

CN is spot on. I'll add, not only install a 180 T-stat, but, it's been my experience to use the Stant "SuperStat" The SuperStat is a better version of their regular T-stat. It has a small bipass built in to allow some coolant to flow when still closed, and it's very accurate.

Just for fun, I'll shoot the temp with a cheap IR gun at different areas of the engine. You'll be surprised that the heat will differ greatly depending on where it's measured.

[chevynut]

Just for fun, I'll shoot the temp with a cheap IR gun at different areas of the engine. You'll be surprised that the heat will differ greatly depending on where it's measured.

The accuracy of those infrared gun readings depend on the emissivity of the surface being measured. A black surface will measure significantly differently than a silver or white surface that's at the same temperature. They're really not that accurate as far as absolute temperature unless you know and can set the emissivity of the surface, but can show differences on the same surface.

[55mike]

The accuracy of those infrared gun readings depend on the emissivity of the surface being measured. A black surface will measure significantly differently than a silver or white surface that's at the same temperature. They're really not that accurate as far as absolute temperature unless you know and can set the emissivity of the surface, but can show differences on the same surface.

I had to google "emissivity" (chuckle..) ... and yes, I found black surfaces and different metals to have different readings. Interestingly, my t-stat housing seemed to match closely the temp I figured it should be, based on the 180 t-stat.

[jackaustin]

On the subject of cooling, my neighbor just finished building a really nice 68 Roadrunner with a 500CI stroker engine. He set up his electric fans to run at two speeds using a Dakota Digital fan controller like mine. I gave him my relay wiring setup and he confirmed it worked.

He was complaining about his engine reaching 205-207 when he drove at slow speeds. On the highway everything was fine and he ran around 180, which is the thermostat he was using. I suggested checking options on mtautoparts.com before he kept talking about changing the thermostat to a lower temperature and to a higher pressure radiator cap, and I tried to explain to him that would do nothing.

I went for a ride with him one day and we drove for 20 or so miles. He kept watching the temperature and I finally asked where he had his fan setpoints at. He had the low speed (half speed) kick on at 190 and the high speed kick on at 205. I guess he thought that he only wanted the fans to go to high speed if it got that hot. I told him the car was running exactly the way he set it up. The low speed wasn't pulling enough air to cool the engine under certain conditions, and he wasn't letting it kick to high speed until it was hotter than he wanted it to run. I told him to set the low speed at 185 and the high speed at 195 and try it. He said it worked perfectly and now never goes above 195.....imagine that.

Your engine isn’t running too cool to be safe, but 160–170°F is a bit below ideal for a Chevy 305. Running slightly warmer, around 180–190°F, is better for efficiency, fuel economy, and proper lubrication. So yes, it would be better for gas mileage and overall performance if it ran a bit warmer.