1965-66 Commando Valve covers

I wasn't aware silicone even existed in 1965. I know none of it made it to the shop I worked at, until much later. Then many mechanics started using that blue crap on everything, it was awful.

I know a little about heat disapation, one of our good customers, makes nothing but heat sinks. If the valve cover was not helping with heat disapation, I should be able to lay the inside of my arm on it.