Does the rear side of the block need any paint, the side under the bell housing?

 

I dont know if any ov the block "needs" paint. But if the motor is out and your painting the rest of it why not? The bcak of mine is painted, came that way from my machine shop...

 

Just out of total curiousity, would high-temp paint help AT ALL to keep engine bay temperatures lower or is painting our blocks PURELY asthetic only?

 

I would think that painting would actually retain heat more, maybe I am wrong. Not sure how it would affect the underhood temps.

I would say the later especially considering how bad cast iron will rust.
Guess I will go ahead and paint the rear too.

 

There are paint additives that make the paint inslulate, but I only use them on headers. I'd rather let heat out of the engine block, even at the expense of slightly higher underhood temps. And, the block really isn't hot enough to affect underhood temps much, compared to exhaust.