1962 340 hp thermostat

[David L.]

Re: 1962 340 hp thermostat

I basically have the same question.

Recently I replaced the fan-clutch system on my 1998 S10 pickup (4.3L eng., 5-spd. M.T.) with a dual electric fan assembly made for a 1998-2004 Dodge Intrepid and some modifications to my fan shroud. At the same time I replaced the 195 degree thermostat with a "Murray Ultra Premium" thermostat (part # 15119, 195 degrees) that I bought at O'Reilly Auto Parts that has a "Larger than OEM opening allowing for up to 50% increase in coolant flow". During normal driving this summer my temperature gauge stays at about 195 degrees except when I am in stop and go traffic on a hot day which then kicks on the dual electric fans when the gauge reaches about 205 to 210 degrees. Prior to the fan assembly conversion the temperature gauge was always at about 195 degrees in the summer (highway driving as well as stop and go driving). How does "an increase in coolant flow" at the Murray Ultra Premium thermostat help while the temperature remains the same? The coolant flow rate varies with the rpm's of the engine water pump assuming the thermostat is operating correctly and is not stuck in the closed position. The coolant flow rate (Q (in gpm) = AV) before the thermostat would be the same as the coolant flow rate after the thermostat (assuming the same RPM) since it is a closed sysyem. In my opinion the only change using the Murray thermostat with the 50% larger opening (A = x-sect. area) would be a decrease in the velocity (V) at that point.
Q = (A1) x (V1) = (A2) x (V2) where A2 = 1.5 x (V2)
therefore, V2 = 0.667 x (V1)

[Duke W.]

Re: 1962 340 hp thermostat

Isn't it simple thermodynamics...at constant pressure, the opening or physical size of the thermostat pass through opening will either pass more or less water flow...the question is...is one thermostat bigger than the other and what impact does that have on cooling? or is it moot!

It's fluid mechanics and for a given head (pressure differential) flow is linearly proportional to area. In a SAE paper on the development of the (nineties) LT1 engine it was mentioned that the pump design was based on obtaining high flow rate through the heater core at idle to maximize passenger compartment heat in cold weather. That implies that the pump rate is higher than necessary for optimal engine cooling.

Duke

[Terry M.]

Re: 1962 340 hp thermostat

It's fluid mechanics and for a given head (pressure differential) flow is linearly proportional to area. In a SAE paper on the development of the (nineties) LT1 engine it was mentioned that the pump design was based on obtaining high flow rate through the heater core at idle to maximize passenger compartment heat in cold weather. That implies that the pump rate is higher than necessary for optimal engine cooling.

Duke

The pump rate on those Gen II LT1s is probably higher than needed at some engine speeds. On B/D-bodies there is a restriction in the heater hose to lower the coolant flow through the heater at highway speeds. In their cost conscious wisdom GM/Chevrolet made it from plastic, and we have to replace them often. Lots of angst about that on the Impala SS/Caprice sites.

[Joe L.]

Re: 1962 340 hp thermostat

The pump rate on those Gen II LT1s is probably higher than needed at some engine speeds. On B/D-bodies there is a restriction in the heater hose to lower the coolant flow through the heater at highway speeds. In their cost conscious wisdom GM/Chevrolet made it from plastic, and we have to replace them often. Lots of angst about that on the Impala SS/Caprice sites.

Terry------


That plastic tee restrictor is not just used on B/D bodies. There's one on my old 89 Eldorado. GM calls these things a "valve". A few years ago when I had the car in for a smog check, the technician was probing around and the plastic tee broke, spewing scalding hot coolant in his face and eyes.

[William M.]

Re: 1962 340 hp thermostat

From my records the thermostat used on the Corvette engine prior to 1963 was a 170 degree Delcostat thermostat. I also have NOS 160 and 180 degree Delco thermostats in addition to the NOS 170 degree Delco thermostat pictured. MVC-016S.JPGMVC-017S.JPGMVC-018S.JPG

[John D.]

Re: 1962 340 hp thermostat

Dino, Biggest complaint is the lack of a dimple on top. it's a raised dimple. John

P.S. Dino, A dimple is a depression. 63 to 65 FI and some of the earlier years have dimpled studs holding the FI onto the base plate.
The water outlet studs (more than one variation) have a tit on top. With circular machine marks leading up. When the cutting tool is not dead center the end result is this raised tit. There is a term for this but I forget it.

[Dino L.]

Re: 1962 340 hp thermostat

John.....could you post what the water neck stud should look like?
thanks
dino

[John H.]

Re: 1962 340 hp thermostat

I only remember 160* thermostats from the 50's, when alcohol-based anti-freeze was commonly used, and glycol-based "permanent" anti-freeze was an extra-cost item. When I ran a Shell station in East Lansing, Michigan in 1960-62 when I was in college, we kept a barrel of the old blue alcohol-based anti-freeze on a rack next to the building for the students who couldn't afford the "real thing" for their winter beaters.