SBC Ideal Operating Temperature Range
Team Owner
Joined: Aug 2007
Posts: 58,061
Likes: 7,146
Army
I'm in the heat of Orlando with a 270HP solid lifter original '61 and, after adding a vacuum advance, removing the fan clutch and adding a spacer/better fan, (kept same radiator) and padding all the holes around the crummy fitting original fan shroud I run 160 deg to 180 deg with an occasional excursion up to 190 when stuck in traffic in 98+ deg weather. Car cools right down once moving. Before these changes the temp gauge would creep up to like 220 and I wasn't happy with that at all.
I DID have to block off the heat risers and fabricate some carb spacers to stop the fuel percolation issues on today's crapola gas.
I DID have to block off the heat risers and fabricate some carb spacers to stop the fuel percolation issues on today's crapola gas.
Safety Car
Joined: Aug 2006
Posts: 3,548
Likes: 36
From: Location, Location QC,NY
Paul
Le Mans Master
Joined: Apr 2004
Posts: 7,106
Likes: 38
From: Newark DE
I don't know if I totally agree with you on this. I have the bone stock 327/300 in my '62 with the original rad. It was running at 195ish at all times, city or highway regardless of outside temp. When I replaced the coolant, I saw that the PO had installed a 195 t-stat, so I replaced it with a 180. The car now runs at about 180ish, city or highway regardless of outside temp etc...
Paul
Paul
By changing out to a 180º t-stat your new minimum operating temp is 180º.
If your cooling system is in good condition and has the capacity to to cool efficiently enough you can pretty much keep the operating temp at or close to the t-stat temp which in your case seems to be.
On the other hand, if the cooling system was lacking, lets say a low BTU level radiator that can't cool well enough, airflow problems, or whatever, just because you changed out to a lower t-stat temp doesn't mean the actual operating temp will go down.
If your motor and the condition of the cooling system dictates that your motor wants to run at 210º for example it wouldn't matter if you had in a 160º, 180º, 195º or whatever t-stat.
The t-stat will only control the MINIMUM operating temp, not how high the actual operating temp may go up to
Drifting
Joined: Jul 2005
Posts: 1,615
Likes: 37
So, based on this I will say that my new average is 192 and not 180.
Le Mans Master
Joined: Mar 1999
Posts: 5,401
Likes: 986
From: Itasca IL
Today is the first really hot day in Chicago this season, and my "new" 66 L-79 seemed to be hovering between 210 and 220 in traffic. Based on my experience with a prior L-79 and the big block 71 I had, this seemed a little high for my preference. While mostly correct, my car does have a copper/brass radiator which I intend to replace in due time. For grins, I looked in the owner's manual, and it states "During normal operation, gauge will indicate around the 210 mark. Hard driving, heavy traffic with stop and go, or prolonged idling in hot weather will produce a reading around the 230 mark."
Burning Brakes
Joined: Mar 2004
Posts: 1,108
Likes: 4
From: Plano Texas
One item that is sometimes overlooked is the type of gasoline we put in our cars. The carburetors of the 60's were calibrated with a stronger blend of gas that had a higher octane and other ingredients without worry of emission regulations. In most large metropolitan areas, such as D/FW, we are now forced to run "reformulated gasoline" that is "oxygenated" with oxygen molecules. As such, the gasoline runs leaner in the combustion chamber because the fuel contains oxygen designed to make it burn more efficiently. I know of no chart or article that can crossover metering jets in 60's carbs to what would be needed to run oxygenated fuel in the same carb today. However, through trial and error, I have found that a 5% to 10% increase in main metering jet size improves my engines performance, makes them cooler running and they seem to run smoother with less likelihood for hard starting and percolation. Unfortunately, gas mileage suffers with the increased jet sizes, but my engines do run cooler.
This advice is worth what it cost ya!! Good luck.
This advice is worth what it cost ya!! Good luck.
Instructor
Joined: Sep 2015
Posts: 137
Likes: 17
This thread makes me less nervous about my SBC creeping up toward 200 degrees with a 180 degree thermostat. In Los Angeles traffic (similar to the "3 mph parade" reference earlier) I am frequently trying to find a place where I can cruise in 4th for a while to cool down the engine. I guess maybe I will just relax when the temp is 200 and enjoy the parade.
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Instructor
Joined: Sep 2015
Posts: 137
Likes: 17
One item that is sometimes overlooked is the type of gasoline we put in our cars. The carburetors of the 60's were calibrated with a stronger blend of gas that had a higher octane and other ingredients without worry of emission regulations. In most large metropolitan areas, such as D/FW, we are now forced to run "reformulated gasoline" that is "oxygenated" with oxygen molecules. As such, the gasoline runs leaner in the combustion chamber because the fuel contains oxygen designed to make it burn more efficiently. I know of no chart or article that can crossover metering jets in 60's carbs to what would be needed to run oxygenated fuel in the same carb today. However, through trial and error, I have found that a 5% to 10% increase in main metering jet size improves my engines performance, makes them cooler running and they seem to run smoother with less likelihood for hard starting and percolation. Unfortunately, gas mileage suffers with the increased jet sizes, but my engines do run cooler.
This advice is worth what it cost ya!! Good luck.
This advice is worth what it cost ya!! Good luck.
Instructor
Joined: Sep 2015
Posts: 137
Likes: 17
Safety Car
Joined: Jul 2022
Posts: 3,983
Likes: 1,610
From: Eastern MA
Old thread but I guess it goes to show that this is needed info. I don't read old threads top to bottom but when an overheat thread comes up, I like to mention 1) that the over-pressure in your cooling system means your boil over temp is around 247*F with a 15psi system, and 2) idiot lights became standard because concerned people "read into" their gauges too much and saw possible issues when there were usually none. Manufacturers addressed the problem but only alerting the driver when an issue was present.
If I have a car running 200* as the norm, it might make me look into what's going on but I wouldn't actually worry.
If I have a car running 200* as the norm, it might make me look into what's going on but I wouldn't actually worry.
