1962 Thunderbird. Hard to start after warm

[74 Harley]

Start by removing the vacuum hoses and plug the ports off. Start car with a vacuum gauge hooked up. If it runs well adjust carb. You could have a bad booster.

 

[Frankie the Fink]

A major exhaust manifold leak is usually heard as a tick or snap which increaes with RPM and is loudest when the engine is cold. Remember 4 stroke engines, are suck, squeeze, bang, blow; and the parts on the "suck" side of things are prone to vacuum leaks - meaning the induction parts such as carb, intake manifold and somtimes PCV systems. I've never had a vacuum leak at a valve cover or exhaust manifold. As noted, if you have a power brake booster its worth checking that as well.

Also I've prob put two dozen Pertronix conversions in vintage cars, there was a spate of Meixo-built Flame Thrower coils that had intermittent failures, the latest ones seem to be fine, but if yours is an older one I'd replace it.