ORIGINAL: Tired Old Man
I'm not going to provide specifics but simply accept I know more about this subject than most. DON'T use a bakelite cap.
I just went out and looked at the Bakelite caps on my Motorcycle. They also have a rubber boot that fits tight on spark plug. The inside of cap has metal grips that makes it hard to even pull the entire cap off sparkplug. The brand is Denso....they also make spark plugs. Capt,n