If I remember correctly, the Cap'n recommended the basic copper-core single-prong spark plugs for our 914s. Any other advice out there?

Also, since we're here, how about for modern engines? Are the super 4-prong iridium fusion-reactor plugs worth it?

Thanks,
Konrad

Yes, copper for 914's and air cooled 911's.
Modern engines, I have no idea, I imagine follow manufacture recommendations.

for the 914 try to find bosch w7cc. over here the W7 are hard to find, they will try to sell W8 ones instead. Of course there are several NGK options if you do not want to go for a Bosch plug.

IIRC, the Cap'n recommended NGK B6ES or Bosch W7CC.

Provided it's stock, I'd go with whatever the OEM recommends since they do spend a ton of money on plug selection. Modern engines are pretty well integrated systems.

914 stuff is like noted above. Copper for the win.

Buy the plugs spec'd during production. If it was ACDelco iridiums then buy those and not the cheaper crap.
The 4 prong are usually spec'd for high pressure direct injection turbo motors.

Copper or solid core only, for some reason aircooleds, both /4 and /6, don't like fancy plugs.

Also Bosch and NGK have rolled threads, plugs like champion have straight cut threads and are more prone to stripping the threads out of the head.

Now that's useful information! I remember back in school watching about half the threads vanish into the combustion chamber of my old Nissan 200SX the first time I changed the plugs.