Correct Spark Plugs

W=14x1.25mm thread
7=heat range
D=19mm thread length, 3mm tip projection
C=copper

W=14x1.25mm thread
R=suppression resistor
8=1 step hotter plug
A=12.7mm thread length, 1mm tip projection
C=copper

If your cylinder heads used 19mm (3/4in) reach plugs, don't replace them with those 12.7mm (1/2in) ones. You'll badly shroud the spark and the exposed threads in the heads will promote detonation.

1/2in was used on old stock heads. New stock heads and performance heads use 3/4in plugs that are less likely to strip.

Thanks Justin.

 

Great info.  Yes, the new plugs are about 1/4in longer.  Gotta take back the new ones and get the correct replacements.

 

Thanks, Grant

Meant the new ones are 1/4 "Shorter".  Thanks, Grant

You can also use an NGK BP5ES or BP6ES.

They just looked up 1970 VW 1600 engine (or so).  Plus you don't need the resistance which is to prevent ignition noise in radio.  Most plug wires are resistance wires which do same job.  Or you might need even a have a radio or experience interference.

Quoted from the Samba:  "W8's are hotter running plugs for most normal driving conditions as well as colder climate and lotsa stop n go traffic. 

W7's are colder running plugs for warmer climates and extended/high rpm highway driving. Usually the plug of choice when building those hi-perf motors as well because they tend to run a little hotter than stock."

 

If you'll be running mostly in the warmer months (like the rest of us), then get the W7's in the proper shank length.

I'd pull one of the old plugs and see that it is the same length as the new ones.  Just sayin'.

 

Too long and you could have a gapping problem as well as a gaping problem...

Hey I think that may have been my first quip of the new year. Oh, it was the removing the deck lid quip. But this may have been a little better.

All Type4 engines will take a 3/4" (19mm) long reach plug.  It's only with the T1 that confusion sets in -- varying reach and diameter depending on heads selected.