I have a radiator and flex fan from a 68 Delta 88 with A/C and 455 engine, when I put the 455 (.030) in my 67 Cutlass I used this radiator and flex fan and the engine ran 180 degrees all day. I just replaced the 455 with a 67 400 (stock Bore) and with the same Radiator and flex fan the engine temps go quickly to 210 plus. I have 180 degree thermostats in both engines. The flow thru the radiator after the thermostat opens is good. I flushed the block and radiator and the coolant was clean, no rust. My question is if this set up cooled the 455, why does the 400 run so hot? Thanks

 

If it worked with the 455 it should work with the 400. How long to "quickly to 210+" does it take? What are your timing settings and what distributor are you running?

 

210 F is not hot. It is a perfectly normal engine operating temperature.

 

Timing is set at factory 8 degrees, distributor is stock breaker point. I know todays engines run at 210 but being old school I like vintage engines to run around 180 to 190. At fast idle, I shut the engine off 210 and climbing, less than 2 minutes. Thanks

 

Yesterday's engines ran at 210 also, without problems. Engines that run hotter are more efficient. The thermostat only controls the temperature at which the thermostat opens, not the final operating temperature.

I have a '67 Delta 88 with a temperature gauge, and it routinely runs between 200 and 210 all day long with no problems.

You're chasing a phantom.

 

Ideally, the radiator should always be able to outcool the engine and the thermostat should regulate the system. Sort of like your home AC has a thermostat, and the AC system can always out-cool the heat, so it cycles (in a car's case, restricts flow). However, old cars are not ideal, so many thermostats just open and stay open, and the radiator does the best it can, which is why the temp fluctuates. (Also, I think new gauges are not very precise, so, along with good radiators, this is why it gets to 50% on a new car and stays there.)

 

Less than 2 minutes to get from ambient (cold start) to 210*?

 

I understand what you are saying, but all thing being equal why would the 400 run 30 to 40 degrees hotter than the 455? Thanks

 

Yes to the 2 min

 

May want to check gauge

 

If its jumping up to and over temp in 2 min's there is an air pocket in the system and it needs to be flushed out. I generally will leave the cap off and observe when the thermostat opens. Once it opens and starts to flow in the radiator, the level will drop and I stick the end of a low flowing garden hose into the radiator to force water in and flush the pocket out.

 

Thanks, I also thought about the air pocket and had already flushed the system just as you said and it "burped" several times. I will check the gauge.

 

The simple answer is something is not equal. You just have to find out what that something is.

Things to consider:
- The radiator may have an internal blockage. When the engine was out, something may have gotten into the system and plugged some radiator tubes.

- The radiator may have an external blockage. Check for debris blocking air flow through the radiator fins.

- The 400 may be generating more heat, possibly due to something such as tighter piston-to-cylinder clearance, tighter bearing clearance, etc.

 

The simple fact here is you cannot boil water in 2 minutes.

 

You can boil water in .2 seconds, if you have enough heat, like that Hawaiian Volcano. However, a cold Olds block cannot make heat enough to boil in 2 min.

 

 

Interesting!