I'm not sure what the best running water temp for the 300 is, but mine runs up to about 210 max at times. Is this alright or is it too high. I am going to have to do some real up hill climbing in about a month and don't want anything to over heat. Thanks

 

I found out the best temp, but still want to know if 210 is alright and won't cause problems over the hill. Also I have another question. What causes the engine to "chug" for a few seconds after the engine is shut off?

 

The standard thermostat for the 300 is 195 degrees-- the engine will then run about 210 around town and slightly lower on the highway, depending on the outside temps. The engine temp will vary from 195 to 230, depending on load, how good your cooling system is and outside temp. If it goes up ,230-240, and stays there you might have a problem.

stractor

 

The run-on after the key is off is dieseling. Several possibilities: carbon build-up, heat range of plugs too hot, engine overheating (but 210* is normal,) or overadvanced timing or idle speed set too high. Try running a pint of water slowly through the intake at 2000rpm to blow the carbon out. You can suck it out of a container using a small vacuum line from the intake manifold if it's efi, or just pour a very small stream down the carb. If that doesn't do it, make sure the timing is set right and check the heat range on your plugs.