engine running temp.

[norm]

I have a chevy 305 from a 77 nova in my 55. I was wondering if the engine can run too cool. I'm in florida temp is only just short of 90 deg. hum is about 68 %. While crusing at about 40-45 mph with the ac on . my temp gage is just over 160 but short of 170. would it better to have it running at a higher temp or good where it is at. Better gas mileage if running warmer?

[chevynut]

I have a chevy 305 from a 77 nova in my 55. I was wondering if the engine can run too cool. I'm in florida temp is only just short of 90 deg. hum is about 68 %. While crusing at about 40-45 mph with the ac on . my temp gage is just over 160 but short of 170. would it better to have it running at a higher temp or good where it is at. Better gas mileage if running warmer?

First I'd check to make sure your gauge is reading correctly. If it is, you might want to see if your thermostat is stuck open. I would think that under those conditions your engine would want to run higher than 160. Most guys have problems cooling, not getting the engine hot. The engine is more efficient running at a higher temperature, and I personally would use a 180 thermostat.

[norm]

I will double check but I am pretty sure the thermostat is working When I was working on it a week or so ago I could tell when it opened by feeling the upper hose. thank you again for your help. ON my last post you helped with on the ac not being cold it did turn out it had a bit too much refrigerant in it

[markm]

Consider yourself lucky and call it a day. There are lot of guys who would love to have your problem.

[norm]

thanks

[markm]

Those old 305s tend to run cool, I have one in my Dads 46 Chevy 1/2 ton with a 65 Mustang radiator and it runs cool. Mine has a non-computer controlled Q-jet from an 84 Chevy van. Actually move along pretty well in the old truck with a 8.5 ten bolt 79 Camaro 3.08 Posi. and a TH350. My Dad drove it in many Shrine parades and many of his buddies had heat issues with their rides.

[norm]

does running cool like mine have any affect on performance or mileage?

[markm]

No race car I ever had ran as fast off ET when I pulled on the track above 160. I believe these cars actually came with 160 stats, I seriously doubt there is any notable difference in milage between 170 and 180 on a motor equipped like yours.

[chevynut]

does running cool like mine have any affect on performance or mileage?

Since you don't have a race car where mileage doesn't matter, the answer is yes. Any internal combustion engine is more efficient operating at higher temperatures. An adiabatic engine, if it could be made, would be 100% efficient. Simply put, the more heat of combustion that you lose to the cooling system, the less heat there is to make power. A cold running engine is more prone to developing sludge in the oil. New cars run at higher temperatures for a reason. We're not in the 60's anymore.

As I said, I would check to be sure your gauge is reading correctly before I did anything, but I would use a 180 thermostat if it's really running 160.

Also keep in mind that a thermostat doesn't regulate your maximum temperature, it regulates the MINIMUM temperature. The thermostat is there to help warm up the engine and to keep the engine warm. Some guys think you can fix an overheating problem by going to a lower temperature thermostat, but that does nothing to address it.

Your engine's temperature depends on how much heat is generated, and how much is removed. If you have a small engine, or drive slowly, you burn less fuel, making less heat. If you have a large radiator and an efficient cooling system, you can remove more heat. If you generate less heat than you're removing, the engine temperature drops, and if you generate more heat than you're removing, the temperature rises. Once the thermostat is wide open, it might as well not be there because it does nothing. Then engine temperature is then regulated by how much heat is removed via the radiator. This is partly why most new vehicles have electric fans, so the engine temperature can be regulated independently of engine speed or load.

Here's a good thread on the subject that I found....

https://www.thirdgen.org/forums/tech-general-engine/24919-those-you-who-think.html

[busterwivell]

I have a basically stock 350 in my 56. I have a 180 thermostat. When I leave the house and temps are in the upper 70'/low 80s I'll run 160/165 when driving at 55. When the temp goes up into the 90's, and I have the AC on, My temp will go up, sometimes to 200/205. I don't think I have anything wrong. I don't think you do either.

Bill

[chevynut]

I have a basically stock 350 in my 56. I have a 180 thermostat. When I leave the house and temps are in the upper 70'/low 80s I'll run 160/165 when driving at 55.Bill

If that's the case, either your thermostat is defective or your temperature gauge is off. The engine should never run that much below the rated temperature of the thermostat. I believe a 180 thermostat starts to open around 180 +/- a few degrees.

When the temp goes up into the 90's, and I have the AC on, My temp will go up, sometimes to 200/205.

Under these conditions your thermostat rating is irrelevant. Whether 160 or 180 it's wide open, and the engine temperature depends on how good your cooling system is. The only way to make it run cooler is to improve heat loss from the cooling system.

[chevynut]

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. 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.

[norm]

Thanks guys for all the great info. It helps a lot . I will just check to see if the gage is accurate and leave it alone
Norm

[chevynut]

Thanks guys for all the great info. It helps a lot . I will just check to see if the gage is accurate and leave it alone
Norm

If the gauge is accurate, and you're really running at around 160, I'd change the thermostat as I said. If you read the thread I linked a few guys did that and gained some mileage. Every little bit helps. 190-200F is not really that hot.

Here's some more light reading for you.

https://www.motortrend.com/how-to/how-to-choose-a-thermostat-for-your-classic-car/

[norm]

just some info, I checked the temp gage against an ac thermometer. The gage is reading the correct temp.