Triumph Repair: running hot, combustion gases, incoming air

Question
Hi Scott,
I have a 1975 spitfire and when I drive around the city the temp is around 190 to 200 degree's but when I get on the highway it goes up to 220 to 235 degree's is that to hot for the car and what can I do about it.  Just so you know I did put a new radiator already in the car and water pump. Any advice you can give me would be helpful.

Answer
It could be restricted air flow into the engine compartment. (check the front valance and cowls aren't blocking incoming air)

It could be blow by of combustion gases into the coolant (compression test, leakdown test and/or pressure test the cooling system)

It could be a faulty thermostat.

It could be timing too far advanced and/or the engine is pinging.

It could be too lean a mixture in the carbs.

It could be a blockage inside the block/head.