Spark Plugs for the 912

[NC Bill]

I just bought the plugs for my annual - the NGK DCPR8E.

 

But I notice that these are marked 4179 while previously I used 4339.

 

What I've learned on the internet is:

NGK 4179 DCPR8E
   Gap      .036” (0.9mm)
   Terminal type   Solid

NGK 4339 DCPR8E
   Gap      .028” (0.7mm)
   Terminal type   Removable Nut

 

Are the 4179 interchangeable with the 4339?

[Anticept]

No. You must use 4339. 4179 are one piece cores without threading knobs. 4339 have threaded knobs which you remove to expose the threading for the plug connectors.

[rhanson]

Yes, my new plugs are 4339 ( from O'Reillys auto parts ); cannot tell what old ones are, other than

 

the DCPR8E id.  912 is running fine so far.

 

RH

[Doug G.]

If you can't take the nut off to get at the threads on top they will not work.