Temp problems

[nail*r]

I have 1965 skylark GS convert with a 401 nailhead 4 speed manual tranny. Gets hot on the highway, not in the city????? Replaced the thermostat with original 160, clutch fan, off the shelf chemical flush. Sounds like a flow problem right? Soon I will be replacing the radiator.

Any ideas???????????

[1965Buick]

Done any tune up type stuff lately like swapped out plugs or played with the timing at all?

[nail*r]

Could this stuff really make that much of a difference? The reason I ask is because it gets hot fast and I mean hot. Above 220

[65Lark]

Check your flow inside the radiator and also see if your heater gets good and hot when you turn it on.If you replaced the stat and know its working OK you may have a waterpump out possibly.I have seen many new stats that were junk right out of the box,hope you get it figured out.........