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Proper running temp for 1275

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mikeamondo

Jedi Hopeful
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So now that I'm able to test drive a bit... what is the proper / ideal running temp for my 1275 powered Bugeye? And, at what temp do I need to pull over and let it cool down?

Sitting it traffic last time, it was approaching 200... I'm thinking that's way hot, but I need to test it more to get good results.

Thanks!
 
Mike,
It should depend on your thermostat, but below boiling is good. The thermostat sets the ā€˜minimumā€™ temp and the efficiency of the cooling system (radiator, radiator cap, water pump, block, head, and coolant) should set the maximum. Iā€™m pretty fond of 185-190* thermostats as an all around temp.
Rut
 
If I'm swapping out the themostat (It's right up on top, right?)... is there a particular source to get that from, brand to use, or brand to avoid? Any pitfalls here to just putting a new one in to be safe?
 
Mike,
I just buy mine from the flaps (friendly local auto parts store), but I always test the new one and my old one to make sure they are accurate. Pot of water on the stove with a thermometer in it and it should open close to the marked temp.
Rut
 
There is with Radiator Cap. Takes a special one.
 
Bugeye's down flow radiators do not use an expansion tank which requires an 8lb deep seal radiator cap. If you are running straight water under 8lbs of pressure your boiling point is 233*F. If your running a 50% dilution of antifreeze with 8lbs of pressure your boiling point will be 248*F. I donā€™t run a thermostat, I run a blanking plate but I like to keep my temps around 175*F to 185*F.
 
So... 15 mile drive, 40-50 mph, good number of fairly steep hills along the way.... Ran mostly around between 190 and 200. Toward the end of the drive, crept over 200. Parked back in the parking lot and let it idle to simulate traffic... was sliding towards 212 when I shut it down.

So seem a smidge on the hot side of normal. I think I'll replace the stat and the cap for starters. Should I do a flush as well, and if so, what's the method?

Thanks!
 
Mike,
That sounds pretty normal and I wouldnā€™t worry unless you got up into the 225* range on a regular basis. A good flush might be in order since our cars are old and Iā€™m sure thereā€™s sludge and old rust from the engine lurking about. I try to do a reverse flush to move as much stuff out the way it came in after a good long soak of a commercial cooling system flush. Keep your cap and thermostat for now to see how the engine behaves after the flush...you may be golden. Another thing you can do if your car overheats and your cooling system is ok, is to check both timing for too much advance and carbs for a lean condition. Dont mess with this stuff unless you have a problem and have no other alternative. You can also run a 25/75 solution of antifreeze (75% water) since water is a better heat remover than antifreeze. Good luck and let us know how it goes.
Rut
 
My '69 is apparently one of the coolest running 1275s out there. Even in bumper to bumper traffic, it never makes it more than halfway up the temperature gauge. It's definitely not a sticking thermostat -- you can see the needle drop when it opens. Longbridgehealey - the previous owner had the same observations. I kind of figured it was one of those "if it isn't broke, don't fix it" situations.
 
It might be worth the effort to take some pictures and measurements of your radiator cap. If that is not sealing properly your water temps are not going to correlate to the engine temps and you will not get efficient cooling.
 
Happy to do that... what exactly am I measuring, and I'm assuming the pics are to show you guys on here to see if it's the correct cap? I would also like to understand exactly how the cap effects the cooling, if you have a second to explain it....

Trevor Jessie said:
It might be worth the effort to take some pictures and measurements of your radiator cap. If that is not sealing properly your water temps are not going to correlate to the engine temps and you will not get efficient cooling.
Click to expand...
 
Morgantown Va is 960' above sea level. Your boiling point of water is 210* at that altitude. As the altitude goes up the boiling point of water goes down. Your Bugeye should have an 8lb deep reach cap!!! If the cap is wrong, defective or not correct you have no pressure on the cooling system so you boil water at 210* Not good!! Read post #6 to increase your boiling point!
 
If the system is not under pressure, then the coolant vaporizes in the water jackets. If the coolant stays in liquid form (by increasing the pressure and thus raising the boiling point) it can carry the energy out to the radiator to be dispersed.

So it is important that the radiator cap sealing ring reaches the flange down in the neck at is rated 8-9 lbs.
 
Excellent description! We are finishing deadline for the mag right now... I'll check it out this afternoon and post a pic of the cap...
 
I don't remember what pressure cap I had on the car but if your cap pressure is too high you can bulge the tank on the downdraft radiator. Experience. The nicest tank I had. I like to run the stock pressure cap which I think is a 4 PSI cap.

Kurt
 
Kurt may be right about the pressure, maybe I'm thinking of the crossflow cap pressure rating.
 
I just checked the manual. 7 lbs for the vertical flow and 15 for the crossflow.
 
OK, I must have had a cap in the teens when i bulged the top tank. Probably was trying to raise the boiling point. Anyway, be warned if the cap is too high of a pressure rating.

Kurt
 
Cap says 7 pounds... here's a couple pics..... spring is .... springy.
Stat1.jpgStat2.jpg
 
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