Ok, we just put a rebuilt 305 in an '86 HO 305 car with a carb. Everything is new or pretty recent. I have a new 2 core 2' all al. radiator, a new lower air dam, a new 180 thermostat with 2 holes drilled in it, a newer cheapy rebuild water pump, newer hoses and when we fill it with water we use a power filler. The car also has a dual elec. fan setup with some shrouding. The car isn't bad with the AC off but with the AC on it runs up to 240 in a few miles and then pushes the water out of it. We have tried water wetter and a ton of other things and nothing has solved the basic issue. At this point I may end up pulling the heads to check the gaskets...any other ideas?

 

man are you sure you got the right water pump and that it is not spinning the wrong way

 

Hrm...the car owner supplied the water pump. Am I correct that this cars water pump spins counterclockwise and older SBC's spin clockwise?

 

yes sir that is correct. serpentine belts spin it counterclockwise and the standard belts clockwise.

 

one92 is correct w/ respect to rotational direction. The problem
arises when either pump is driven in the wrong direction. This
most often occurs when older (v-belt clockwise) pumps are
mounted into newer (serpentine c-clockwise) systems. And
it is VERY easy to get used parts mixed up in this fashion.
However, based on the cooling you say does exist, I would be
surprised if this is the problem.

Here's the experience of another thirdgen'r at a local meet.
All new parts, including a bigger aftermarket radiator, and
results were much like yours. Turns out that to get the
radiator in, it was tilted back some, which created an opening
between the sides and the core support. Heated air was
circulating back around to the front, in a virtual closed loop.
Some small tin block-off plates solved the issue.

Good luck.

 

hey, whats your normal temp without the a/c

 

You probably have an A/C condenser plugged full of bugs, rocks etc. Pull the radiator back out, and clean all the junk out of the condenser. You'll have to pick it out...an air hose, water hose etc. won't do it. As the condenser gets quite hot with the A/C on, you end up pre-heating what little airflow you have coming through it, and the car overheats.