'65 Thermostat several questions

[Oliver S.]

Hello,

I don't know what thermostat (160°, 180°, 195°) is in my '65 300 hp Corvette. Here's what readings of the temp gauge I've observed (the gauge reading is correct - x-checked with IR Gun):
After a couple of miles the gauge shows approx. 170° (normal load). Driving without load down a longer hill and the reading goes down to approx. 160°.
If it's a 160° thermostat that is ok I would assume that it's always around 160° provided that it's under normal or no load when the engine is warm.
If it's a 180° thermostat I think it's defect.
Do my observation points to a defect thermostat?
What would be the right thermostat for my engine, 160° or 180°?
Is it still available from GM together with the gasket and does anybody know the part #'s?
Suppose that I park the car with the nose down the hill ... can I replace the thermostat without draining some coolant?

Regards
Oliver

[Joe L.]

Re: '65 Thermostat several questions

Oliver-----

The original thermostat used for 1965 Corvettes was a 180 degree F unit. 160 degree units were last used in the C1 era (some 1959 models, I think).

As far as your gauge reading is concerned, keep in mind that for a variety of reasons, dash gauges are not completely accurate. Based upon a dash gauge reading, it would be pretty hard to differentiate, say, a 170 degree unit from a 180 degree unit. The best way is to remove the thermostat and see what rating it has. The rating is usually stamped on the unit.

A 180 degree F unit is available from GM under GM #10207381. A 160 degree unit is available under GM #3041424. However, I DO NOT RECOMMEND the use of a 160 degree thermostat.

I prefer Robertshaw 330 series "full flow" type thermostats to the Delco type

[Dennis C.]

Oliver, I don't believe there is any position...

...you can put your car in and not have to drain about a gallon of coolant to avoid a liquid mess.