Re: Running hot

Posted by Tim Cole On 2012/9/14 9:08:50

Dear Pat:

Very common problem as cars age. Including modern cars.

The radiator is rather small to start with, but with A/C there is an additional load. Also, if the idle speed is near the 400 rpm spec there may not be enough flow from the fan.

Solutions are easy to test. Just let it sit in the driveway on a hot day. I have always felt that 400 rpm idle is too slow and inhibits oil splash, so I would raise it to 550 rpm and see how it does. After that some shrouding around the A/C condensor the same way as modern cars. Maybe try the shrouding first.

Beyond that, old cast iron is less efficient and radiators cores do wear out. Also, less that top compression runs hotter so if your gas mileage is not so hot check that as well.

Overall, as long as it is not boiling you are doing pretty good. I did a 56 Carribean that idled hot even with a new core. It had a junkyard block and so was rather weary.