BTW, back in the 80's I had a few rad shops tell me you can NOT clean a plug rad, only can re-core it. If overheats at high speeds, its a clog rad. If its from 1968 its clog, I don;t care if there is only 30,000 miles on it, its freaken old.
Needs a new or re-core rad but could try to just remove the t-stat but I don't know. I used to drive to big rapids for college in the 80's. Car needed a rad also, it be ok for about one hour, then its going to get tricky. Gas stations used to have hoses in back, I would pull off and spray the rad down to cool it off, lots a fun..did help to drive slower, like 60 and not 75
