Can or should you add lead to gas for a 67 Mustang?

Answer 1

The classic engines were built when leaded gas was standard. If you don't burn leaded gas or add a lead substitue to you gas in one of these classic cars, it damages the valve seats. If you were rebuilding the heads of a classic engine these days, most people would ask to get hardened valve seats installed so you can burn unleaded gas without a problem. But since we have been on unleaded gas for about 20+ years now, I would assume if the car is currently driving on a regular basis, it probably has had those valve seats already installed.