65 vette over heat


Asked by Jul 01, 2014 at 03:43 PM about the 1965 Chevrolet Corvette Convertible Roadster

Question type: Maintenance & Repair

have 65 vette with 327 350 hp rebuilt motor yrs ago everthing new rad ,water pump so on .when on eway gets up to  210 have 180 thermostat some one told to try 160 thermostat gets hoter faster.will adle all day not go past 180. what do you might be.thanks

4 Answers


wow- what a car- the 327 hi-po 350 horse is really a screaming engine- like a race engine- everything must be just right- you say it was rebuilt "yrs ago" think how often a race car must be checked and maintained- after every race- you cannot just drive this like an ordinary car, expecting it to run for years without out impeccable maintenance- sounds like you need to replace that thermostat ASAP with whatever temp spec you want- and clean that cooling system while you are at it- now, what else needs looking at? I wish I had that car, I would sleep with it and give it every little thing it needs, everyday-

John Carson

jamnblues is wordy and no help what so ever. I had a 350 HP 65 Corvette, sadly traded it in for my current 69. First make sure the radiator is clear. The radiators back then had a tendency to corrode and the radiator needed to be "rodded out" to open the water passages through the radiator. Make sure the hoses are not collapsing when at operating temperature. The entire engine is made of a poor grade of iron and rust was a big engine destroyer back in the 50s and 60s until aluminum became part of the build. All corvette engines were built stronger than the conventional Chevy motors, to put out more horse power. The 350 HP had a more aggressive cam and I think higher compression. The engine was solid, and did not need tinkering after every drive. I'd look at the hoses to make sure they are good and not spongy, then have the radiator checked. After that and during all that have the thermostat looked at, and since it is cheap, replace it. Does the engine overheat or just show it getting up to 210? Are you in town and with air? The Corvettes always ran hot, and still do. The more HP you put into an engine the hotter it is. More horses, give off more heat. The 180 thermostat means it opens when the engine operating temperature reaches 180 degrees. That is the best operating temperature for the engine. At 160 degrees, the engine does not get hot enough to ignite all the gas, you lose horse power and fuel economy. It also can over time cause engine damage. Keep an 180 thermostat in the engine and find out what the cause of the over heating is. It could be something as simple as timing. Is the cam stock grind or a more aggressive cam? A true dyno tune can set the carburetor, timing and everything else to make it run smooth and enjoyable.


hy.many things can make an engine overheating.first check if all your cooling sistem is find.on a corvette run 2 liters of prestone and the rest put deonised water with water wetter.water cools more an engine than prestone.and gas with low octane or if an engine is too poor on gaz can make an engine overheating.also those original manifolds keeps the heat.so put headers if the engine still overheats it is because the engine was not rebuilt properly.and do not forget on a small block you need one quart of oïl by 1000 rpm.so if you ref 6500 rpm you need 7 quarts of oïl us.224 onces.y am sure of this.tank,s for reading me.

John Carson

It's been 6 months now, have you fixed the problem? Another thing you may consider, if the sending unit and gauge is original, you just might consider testing them to make sure they display the correct readings. Before tearing into an engine for thousands of dollars, eliminate the easy to check cheap items first. If you run straight water, you will overheat. If the radiator cap is defective, you will overheat. The system must be air tight and sealed to work as designed. Antifreeze will help keep the fluid cool the engine, prevent rust and contaminates from blocking the water jackets. If you heat gun shoot the engine to see where the heat is hottest, if it is the heads, take a look and make sure the gaskets have all the water ports open. Some gaskets are universal and don't have holes for all the water jackets on all the engines they will fit on. From experience, this is a common problem.

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