Technical Slightly Hopped up 305 overheating...need some input.

Okay poboyross let's hope all of this helps. Just keep the kids away from the running engine and fan.
A small block Chevy engine should not even need a fan of any kind while at highway speeds. If it is overheating on the road you need a better radiator and better flow.

 

Yeah, about 2/3 of the way through getting the bolts on, a similar thought occurred to me and I was like "dammit". Next time, though....

I'll call this a success, as after installing the 15" fan, filling the system with water, and putting the electric fan back on the front, it took about half an hour of idling in park (higher RPM, I know) at about 1350 RPM, to reach a resting point of about 220. I believe there's still some more air in the system, as I filled it once, then refilled after the thermostat popped open. So there might still be some la***ude to get the temp lower. No Water Wetter in there yet, though.

Thanks to all for the advice...it was a big help!!!

And to answer the "what heads?" question...mine are the double pointed peak ones on this chart. Indicates that they are early 70s heads? Weird, I thought that my block indicated it's a 305 from the early 90s.

 

Sorry for taking so long to respond mate, two 1inch rows should be good. Some cores have a much smaller tube size, two rows with the small tubes would have be part of the problem.

Doc.

 

Glad you got this sorted out.I bought a 72 chev pu years ago that had a engine transplant.After it granaded on the hiway on my way to work ,couldnt figure out why till years later when i was scavaging parts from it realized it was a 400 block with all the 350 gear on the front inc the harm balancer.