Operating Temp. for 1941 Engine

[VooDoo]

Does anyone know the operating temp for the 41 engine. I am doing an engine change with a 12 volt update but want to use my original temp. gauge. I would like to make sure it is working properly and give the correct reading for my new engine before I start driving it. Last thing I want is to be over heating and not have the guage regesiter it.  Also I am assuming I need a voltage regulator before that gauge correct Thanks Andy

[Richardonly]

My 346 flathead runs at about 190-210. (95 degrees+, it hit 220- in traffic.)  Truly depends on the weather temp, whether driving uphill, on flatland or downhill.  Also much higher in traffic.

So, unlike newer cars, mine varies by the driving condition.

Idealy it should be around the thermostate rating, but mine is not.  I added an electric fan (push) and the end of the season and not sure how much it will help with a 6V system.

[Bill Ingler #7799]

As Richard said it depends on driving conditions and outside temp but it also depends on the condition of the engine and the condition of the radiator. In the case of a new rebuilt engine- was the block cleaned to remove all the rust scale and crap in the cooling area around the block? Was the radiator re-cored? Both of these items plus what Richard said will determine what the gauge will register regardless if it is 6 volt or 12. Here is what I have done to tell me what that needle says as to temp. The hottest part of a 346 flat head is the left rear cylinder head just where you find the temp sender. I block the shutters closed on a 41 or use cardboard to block the front of the 47. Start the car and as the dash temp needle starts to rise, use an temp gun to see what different temps are registered in different parts of the radiator. I also use a long meat thermometer stuck down the radiator opening so as to read the coolent temp in the top tank. Look at the dash temp needle and write down the temps you find as the dash temp needle rise through 1/4, 1/2, 3/4, on the letter H and then when the needle is on the letter T. So now when you drive, you have a good idea what temp you have for that engine. Remember that a 9# cap at sea level will add about 2.4d degrees per pound to the boiling point of a 50/50 solution. So if I look down and see my needle at the H, I am running at about 220 and OK on coolant temp for the engine.             Bill

[VooDoo]

I don't know what my original 346 ran at because it never ran. So the typical temp is 190ish? With the gauge reading in the middle? My concern is that if my new engine runs at say 150 I want to make sure my gauge is not reading H like its overheating or visa versa. Is there a way to make sure the gauge is reading the correct temp of the new engine?

[Richardonly]

A temp gun aimed at the sending unit will give you an accurate temperature. (A local repair shop should let you borrow or do it for you.  Why spend $65.00 to test it a few times?  Kinda like I did?, LOL.)

You can also buy an aftermarket temp gauge for under the dash or hidden.  Even somewhere in the engine compartment.
I run two.  The original and a calibrated one under the dash to the left of the steering wheel.

Sadly, there is no answer to your question other than you don't want it to overheat.  A 165 thermostate would ideally read 165.  DON"T expect to see that.  The flow of the cooling system in these old cars were not like today.

The hotter the outside temp is, the hotter the engine will run.

The best I could say is 190 to 210/220 on a summer day would be acceptable to me and my 346.