What's Normal Temp for '70 C10 396?

[mosel70]

My stock radiator and belt-driven fans couldn't keep my 396 (402) from overheating while stopped and in gear. I put in Mishimoto's three-core alum radiator and dual electric fans (2600 cfm) specifically made for 67-72 Checy C10s. Last summer I put in Summit's high volume water pump and a Mishimoto 180 degree thermostat. With 87 degrees outside and stopped and in gear, I'm running 196-202 degrees with IR temp gun pointed at coolant hose just off thermostat housing, but temp gauge needle is just in the red (new temp gauge). I'm running the fans constantly while the engine runs.

As temps are getting higher here in Las Vegas, what is the highest temp I should allow before getting alarmed? Any way to get the temp down?

[Ken B]

I would try another gauge inside the truck, it doesn't seem accurate. The 427 in my Chevelle runs between 190-200 on the hottest of days and it has all stock cooling components.

[Alex V.]

Sustained temp probably shouldn't be over 200, but I wouldn't expect damage from momentary spikes of less than 215-220.

[weq92f]

My '70 402 runs right around 195 when idling with A/C running and in gear, like at a stop light. Running straight fan against a radiator without shroud.

The temp will go to about 220 and sit there if the truck continues to sit and build heat. Once we start rolling, the temp comes back down.

If it's extreme enough, I'll slip it into neutral and bring the RPMs up to around 2000, which will also bring the temp stable or back down.

Hth,

-klb

[clay68c10]

My old 68 would run at 205 with a .030 over 454 in Dallas summertime, a/c on, in traffic or idling or whatever. I think I was running a 195 thermostat. I datalogged my EFI just to watch the temp, it was pretty steady. I was running a Lincoln MK8 fan with a PWM controller. The fan was almost always running at 50% or more once the truck got warmed up.
I recalibrated my stock gauge, it would always be on the edge or in the red. A different resistor on the back got the needle where I liked it. I don't remember what resistance did the trick, that's been a while ago.

Big blocks do run hotter than small blocks, for sure.

[engineer_gregh]

I don't trust the stock temperature gauges. I have a built 402 and had the same issues you are seeing. First thing I would suggest is to add an aftermarket under dash gauge to get a more accurate reading. If in fact you're running hot you might want to play with your timing to see if it will help. Big blocks do run hotter, but I am uncomfortable with any reading above 200 degrees. I'm running dual 1600 cfm fans but with the stock 4 row radiator.

[davepl]

I wouldn't trust the gauge. But if that were my gauge in my truck, that's about 220F, which is getting toasty.

My truck will not hold it's temp in warm (85+) Seattle weather with the AC on, so I imagine you'd struggle a bit in Vegas. Without the AC on it should be able to manage though.

Get a standard thermal temp gun and point it at the thermostat housing, that's how I check my actual temp. I have one in the glovebox right now because I'm chasing a similar issue on my own 1970 C20 396.