65' 365hp - Correct Thermostat

[Jim R.]

Re: 65' 365hp - Correct Thermostat

Joe what bad things can become with using a 160.

David------

For your application the original thermostat was a 180 degree. That's what was used then and that's exactly what I recommend now. 160 degree is too low for a modern engine (and, even 50 year old engines are modern in this context) and a Corvette cooling system will only be able to maintain a 160 degree temperature if the ambient temperature is frigid.

However, I do not recommend the poppet-pellet type thermostat (the type that Wayne pictured). The Robertshaw 330-180 is the way to go.

[Joe L.]

Re: 65' 365hp - Correct Thermostat

Joe what bad things can become with using a 160.

Jim------


Well, no really bad things are going to occur. The main problem is that a 160 degree will cause a wider range of engine operating temperatures. Consider that a thermostat only controls the LOWEST temperature that an engine will operate at. So, with a 160 degree thermostat you will have a range of 160 degrees to whatever. With a 180 degree, you'll have a range of 180 degrees to whatever (the same "whatever" as with the 160 degree). So, the operating range with the 180 degree is narrower. That's a better situation. Plus, 180 degrees is a very efficient temperature for engines to operate at.

[Edward J.]

Re: 65' 365hp - Correct Thermostat

Joe what bad things can become with using a 160.

Jim, to add to Joes last post, A 160 degree thermostat will sometimes not give the radiator enough time to do it's job, which is to lower the temp. of the coolant, hence over a period of time the temp of the coolant can slowly rise and create a problem of overheating, say if you were stuck in at a traffic situation. Normally everyone thinks that a lower temp thermostat will make the car run better which is true in a sense. but for regular driving a constant temp works better, even more so with the ethanol blended fuels problems for a lot of corvettes with heated cross overs.

[Duke W.]

Re: 65' 365hp - Correct Thermostat

Low operating temperature can cause oil contamination with blowby that can form acids. 180 degree stats became standard when the industry switched to "permanent" (ethylene glycol) base antifreeze in the early sixtes. The previous alcohol-based types boiled off too fast at 180 or more, but higher thermostat temperatures encourage boil off of blowby contaminents in the oil.

195 stats became standard with emission controlled engines, because higher operating temperatures generally yield low HC emissions.

The quoted themostat temperature rating is the nominal temperature that it begins to open. They are not full open until about 30 degrees above the specified opening temperature.

As Joe said (and has said a zillion times) the thermostat only establishes the lower end of the normal operating temperature range. Regardless of the themostat temperature rating the normal operating temperature range with a 15 psi cap is up to 230F. A 50/50 blend of glycol/water with a 15 psi cap does not boil until 265F, so at 230 you still have 35 degrees margin, but if all cooling system components are in good working order, 230 should only be seen in extreme conditions such as low speed stop-and-go driving in triple digit temperatures.

Duke