C2 C3 Original Thermostat Temperatures

[Mark E.]

Three thermostat temperature questions:

1- What temperature thermostats did C2 and C3 cars come with? Did it vary by year, engine, or if A.I.R., NA9 equipped? Joe posted earlier that "All 1968-69 Corvettes were originally equipped with 195 degree thermostats. This was connected to the fact that all 1968-69 Corvettes were equipped with AIR", but I couldn't find info for other years and options.

2- Is the indicated temperature the thermostat opens checked during PV?

3- Are there any data supporting an engine running at 160 degrees instead of 180 or 195 produces more power? Back in the day, I would install a 160 degree thermostat to improve performance (the belief was that a cooler running engine => cooler intake => more dense air charge => more power). Other than maybe some cold weather driveability (not an issue in Texas, especially for hobby cars), any downside to running at 160 degrees?

[Keith B.]

Re: C2 C3 Original Thermostat Temperatures

Mid years with out K19 got a 180. K19 cars used a 195. A t-stat controls minimum tempture ONLY. once it reaches its stated temp it opens. Thats all it does.

[Larry M.]

Re: C2 C3 Original Thermostat Temperatures

Agree with Keith on thermostats for C2 cars.

During PV, the operating temperature will be checked, so a 160 thermostat may cause a problem. It probably will, unless PV is done during the summer time in the heat of the day. Then the car engine temperature may be higher due to limited radiator heat capacity/removal.

I also ran a 160 thermostat in my performance cars back in the day. But I also changed oil very frequently, so the lower temperature of the oil and the residual moisture were not issues. Engine oil needs to be around 190-200 F (or more) to boil off the moisture that accumulates due to combustion. I also lived/worked in SE Texas during this time.

I personally believe that the SB Chevy engine runs best overall with a 180 F thermostat. That is all I use now.

Larry

[Jack M.]

Re: C2 C3 Original Thermostat Temperatures

Mark- There is some thermostat data available in the "Information Kits' provided by the GM Heritage Center.

For 1966 (in the Cooling System section), I find the following:

THERMOSTAT
Type: Pellet
Begins to Open at: 177*-182*F
Fully Opened at: 221*F

For 1968-69, I find the following:

THERMOSTAT
Type: Pellet
Begins to Open at: 192*-198*F
Fully Opened at: 217*F

[Joe L.]

Re: C2 C3 Original Thermostat Temperatures

Mark- There is some thermostat data available in the "Information Kits' provided by the GM Heritage Center.

For 1966 (in the Cooling System section), I find the following:

THERMOSTAT
Type: Pellet
Begins to Open at: 177*-182*F
Fully Opened at: 221*F

For 1968-69, I find the following:

THERMOSTAT
Type: Pellet
Begins to Open at: 192*-198*F
Fully Opened at: 217*F

Jack-------


Many C3 Corvettes with CCS emission control system (no AIR system) used a 180 degree thermostat.

I prefer a 180 degree thermostat for ALL Corvette applications except computer-controlled applications originally using a 195 degree thermostat.

[Jack M.]

Re: C2 C3 Original Thermostat Temperatures

Many C3 Corvettes with CCS emission control system (no AIR system) used a 180 degree thermostat.

I prefer a 180 degree thermostat for ALL Corvette applications except computer-controlled applications originally using a 195 degree thermostat.

Good to know, Joe. I was mainly illustrating the operating range reported in those documents.

[Mark E.]

Re: C2 C3 Original Thermostat Temperatures

Thanks guys.

In summary, it looks like the consensus is:

- Mid-years w/o A.I.R ==> 180 degree thermostat
- Mid-years with A.I.R ==> 195 degree
- 68-69 ==> 195 degree (Joe earlier commented all of these cars had A.I.R)
- "Many C3s" w/o A.I.R ==> 180 degree thermostat

Is there more definitive information for 70 and newer C3s?