66 mustang 200 inline 6 operating temps question

[66mustang0103]

I am a college student and drive a 66 mustang with a 200 and a c-4. Its also got a dual out header and 2 inch exhaust. Currently driving down the highway it stays about 160 F which I think is low. I think it has a 180 thermostat in it now but probably changing to a 195 this weekend. The radiator does leak a little bit, in process of for saving for a new one. I am located in northern alabama if that helps at all. I am currently getting about 20 mpg running 70 most of the time. If I increase the operating temp to about 190 would that increase my mpg? What would be a good operating temp?

Thanks Josh

 

[bubba22349]

Raising the operating temp can give you more MPG, efficiency increases keeping as much heat in the engine as you can without overheating it. However slowing down some would probably raise your MPG more. When you start going over 55 the aerodynamic drag increases. Good luck

 

[chad]

Great Q, Josh!

We had a thread (started by Rich?) about lowering the temp as much as possible (lot of guys from the far west & so. west). But too low not good either -

I'd like to know the same thing:

150* - 200*F ?

bubs points out higher is good, but how close to boiling? under all conditions?

 

[bubba22349]

For many late models 210-212 is normal. Your engine,gaskets, and cooling system, cap presure etc. everthing needs to be in top condition to do that. NASCar racers build everything to extremes with oil coolers etc. 230 to 240 is considered the danger zone.

 

[chad]

so may B 90* - 210?
209* - 212*?
I know it may seem like splitting hairs 2 some but I'm ignorant and think if there's a target - might's well attempt to hit it (the ideal & B happy w/the real).

 

[66mustang0103]

Im goin to try to make mine to where it will run about 190 to 195. It also has a small overheating problem if you let it sit and idle to long like at red lights and drive thrus. I have always been told that for older engines 190 195 is pretty good.

Thanks Josh

 

[CZLN6]

Howdy Josh:

I don't know about your seasonal weather, but here in Idaho where summer heat can be will into the ninties and winter temps can get down to zero, I prefer to use a 180 thermostat during the summer and a 195 during the winter. Kind of a nuisance to change, but it gives me peace of mind. You might want to test your thermostats in a pan of water with a candy thermometer to check for accuracy. More PoM.

Adios, David

 

[66mustang0103]

I live in northern alabama, the winters down here get to the teens or so and summers are right around 100. Im goin to start experimenting with different thermostats to see which work best. My goal is a constant 195 or so.

 

[bubba22349]

In going for more economy you could also use one of the later model air cleaner assembly (later 1960's up) so you can get heated air into the carb during cruise conditions IE stove tube hooked up to bring warm air from headers to air cleaners intake snorkel. The best ones have are a duel system with a vacuum door so it can switch to cooler air when you need the extra power for passing performance. You could also try some header wrap to keep some heat in it.

 

[66mustang0103]

I would like to get the car where it is running its best and happiest. Gas mileage is a good upside though cause its for the most part my daily driver. I already have a problem with the fuel in the carb heating up to much causing hard starts when its warm so not for sure if i wanna put heated air in or not. Once I get the brakes fixed ill find out if it likes the new thermostat or not. I dont think it likes running 160 degrees.

 

[CZLN6]

Howdy Back Josh:

Don't confuse heat soak on the carb with using intake air to the carb to your advantage. They are two different things. Relating to Bubba's suggestion, Using exhaust manifold heated air to the carb intake helps to prevent carb icing and makes for a more efficient warm up for a cold engine. Then switching to cooler, non-heated air, once the engine is warmed up makes for better performance. In Idaho, I like to run heated air all winter.

The hard starting issue is due to heat soak from the engine under the carb. While it is not an uncommon problem it is a nuisance. Try raising your float level. Many here have rigged heat shields isolating the carb from heat below. Also make sure the needle valve in the carb is sealing properly and all vents that should be plugged are sealed to minimize drain back as well as evaporation. Check for leaks, which are hard to track on a hot engine because gas evaporates so quickly.

On the thermostat heat range, FYI the rating is an indication of when the thermostat begins to open. The thermostat does not determine how hot you engine will run. So a winter 195 stat will give your interior heater more heat, and the engine will run more efficiently in cooler weather. You get the idea.

Keep it coming.

Adios, David

 

[66mustang0103]

Thanks for clearing that up about the heat soak, I thought the hot air may heat the carb up to but it may not then. Might do that in a future project. I will definetly play with the float level a little and check for some leaks.
Thanks again Josh