Thanks to all for your replies.
I put a new 160 degree thermostat in (discovered it didn't even have one in it); new radiator cap; burped system to remove any air that may be in it; put in bottle of "Water Wetter"; turned fans to continuous running; insulated fuel line (to cure vapor lock), ran it 100 miles (2 trips) and I think the problem is solved. I did find the trans cooler was blocking a goodly portion of the radiator; also on the other side my power steering apparatus where I add power steering fluid was blocking also. future plans are to try to install bigger fan behind radiator, I have read they are 30 percent more efficient.
Anyway, wish me luck. To answer some of the questions, the engine is a 302 GMC bored to 320, mild street cam; headers; Edelbrock 4 bbl.
