Proper spark plug for Carrera 3.0?

[echrisconnor]

Not sure what plug I'm supposed to have in a Carrera 3.0

Wayne's book recommends a W260-T2, however I'm not sure what that translates to in NGK or conventional Bosch W-rated plugs.

A 1976 2.7 takes a W 5 (cold plug)
A 1979 3.0 SC takes a W 8 (hot plug)

What plug would be best for a C3 (I can give more detailed engine specs if that helps)?

[RickM]

Good question:

To confirm Wayne's recomendation you may want to call Bosch. They're very helpful.

Bosch Customer Service:
888-715-3616
(Monday thru Friday 8:00 am to 5:00 pm CST;
for U.S.)


Here's NGK: 888-800-9629

or 1-877-473-6767 prompt #2 for assistance.

[echrisconnor]

I suppose this should help me, but I still can't make sense of it. Is the 260 a 6 heat rating?

[RickM]

That number doesn't look right. I doesn't cross reference anywhere.

[echrisconnor]

I don't have the book in front of me so I can't double check, but I'm pretty sure that's what it was. Now, I may be making the assumption that it's for a Bosch plug (since it didin't explicitly state what plug). Could it be a Beru number?

I'm curious what other C3 owners are using though. The advance curve on the C3 is closer to a 2.7, but it's still a 3.0 like the early SC... Compression on both engines is pretty much the same. If I want to keep the plugs clean but still be able to run a good amount of advance without preignition from a hot plug, what would make sense?

[RickM]

I stand corrected. It seems that it is a Bosch plug using an older numbering system...it changed a few times over the years.

Searches are showing:

Current Bosch # is W4C1

NGK part # is B8ES

http://www.mzsimson.de/service/Bosch.htm

[echrisconnor]

Wow, a four. That's a pretty cold plug isn't it? Noah's NGK 7 is on the cold side too. Noah, do you have any problems with fouling or buildup on your plugs?

[RickM]

FYI:

NGK's system is different from Bosch. For NGK, the higher the number the colder.
So Noah's 7 is hotter than the recommended plug.

[Early_S_Man]

Yes, the old 'W260-T2' was a cold plug ... only slightly warmer than the infamous 'W265P21' plug recommended for all 911E and 911S MFI engines ... which was later changed to W3DP0.

NGK's numbering system is similar to the old Bosch system in that higher numbers mean a colder plug ... I guess Bosch liked Champion's numbering system, so they changed to a similar system in the '80s!

[echrisconnor]

So, what seems to be proper is:

NGK -- BP7ES or B8ES (higher # is colder)

Bosch -- W3DP0 or W4C1 (higher # is hotter)

Is there any reason to lean hotter or colder here?

[RickM]

Any way to determine the operating temp of a plug while in use?

"By properly selecting the heat range of the plug, it ensures that the plug will operate between the plug’s designed operating range of 500-900 degrees Celsius. In this range, the spark plug will be self-cleaning, yet will not be hot enough to pre-ignite the air/fuel mixture."

[Bill Verburg]

The original spec from the owneres manual was either Bosch W 260 T 2 or Beru 260/14/3 either w/ a .7mm gap

that was for use in the Fatherland where speed limits are somewhat mor erelaxed than over here.

Looking through my records WR5DP and ND W24ES GU where the ones I used over here