Just purchased 69 Camaro and installed new 4 core radiator with 13lb cap.Noticed upper rad.hose stays very hard.I removed thermostat so no blockage there.If I lift lever on cap to releave pressurer, hose becomes soft . Is this normal for Camaros to have so much pressure in cooling system?Engine temp. seems O.K about 165-170.Any info.helpful. Thanks

The system could have excess air which expands more than coolant, but if it is not expelling coolant then you are good to go. Most systems will build at least 10-12psi under normal driving. This "friendly" pressure will aid the coolant in higher vapor points! Water for example boils at 239* with the addition of 10psi of pressure.

Also, it's not good to open the cap under pressure or when warm. This removes that "friendly" pressure and if you continue in your travels this might provoke the coolant to boil away in certain spots not having the additional protection. So, open only when cool or if opened when hot, let everything cool down before sealing off again.