Quick check with others who may know.
Which Bosch "Super" spark plug is correct for the 1975 1.8 engine? FI' if that is pertinent to the quest.
Long thread or short thread, or does it matter?
My old are long and the new ones I got by mail are short.
They were a gift so I didn't order them.....blah blah blah

tia.

MikeCool

Long thread. All 914/4s use the same plug. Sounds like you got plugs for a VW Bug instead.

Bosche W7CC or NGK BP5ES.

The plug thread length is pretty important. If too long, you could run the risk of bumping into the piston and if too short, you will not get a proper combustion. The plug numbers listed above are good ones. The super's are a good plug, but I might go with a resister type if you like your radio and then even step up to the 3 electrode style:

WR7DTC

7 is a good heat range for a daily driver and the DTC's will give you a good spark. The cost more, but only a buck or two.