Spark plug question

['76mintgrün'02]

Unfortunately, you'll find that only the NGK resistor plugs are available now.  They discontinued non-resistor plugs.  You can switch brands, or switch rotors, to offset the added resistance. 

 

The resistor plugs add 5K ohms of resistance and the stock rotor has 5K ohms, but the e21 rotors only have 1K ohms of resistance.

 

I'm using BPR5ES plugs now with the e21 rotor.  I may switch to Champion plugs and put the other rotor in when I am due for new plugs, but I also like the wider tip on the e21 rotor, since I'm using a vacuum advance distributor.  Not necessary, but nice, anyway.

[TobyB]

As to heat range, the construction of the insulator around the center electrode is what varies-

 

 

Heat Range | Basic Knowledge | SPARK PLUG | Automotive Service Parts and Accessories | DENSO Global Website

WWW.DENSO.COM

 

 

t

 

[VWScott]

4 hours ago, TobyB said:

As to heat range, the construction of the insulator around the center electrode is what varies-

 

 

 

Heat Range | Basic Knowledge | SPARK PLUG | Automotive Service Parts and Accessories | DENSO Global Website

WWW.DENSO.COM

 

 

t

 

that is some quality info there,I didnt know that

[JohnS]

13 hours ago, John76 said:

If your engine has not been refreshed (valves, guides, rings) and is burning more oil than normal, you might try BP5 instead of BP6 plugs. These are a bit hotter and kept my plugs cleaner (in the self-cleaning temp range) longer.  

Same here.  My '73 burns a little oil and has always liked the BP5ES (hotter) and my '74 prefers the BP6ES (colder).

[JohnS]

6 hours ago, '76mintgrün'02 said:

Unfortunately, you'll find that only the NGK resistor plugs are available now.  They discontinued non-resistor plugs.  You can switch brands, or switch rotors, to offset the added resistance. 

 

The resistor plugs add 5K ohms of resistance and the stock rotor has 5K ohms, but the e21 rotors only have 1K ohms of resistance.

 

I'm using BPR5ES plugs now with the e21 rotor.  I may switch to Champion plugs and put the other rotor in when I am due for new plugs, but I also like the wider tip on the e21 rotor, since I'm using a vacuum advance distributor.  Not necessary, but nice, anyway.

I always thought that the older style stock wires with the Bakelite resister boots were an issue when using the newer BPR NGK plugs.  I never considered the rotor?  Do you have the part number handy for the e21 1K rotor?  Are you using resistor boot old school style wires with it?  I always thought that I could switch to using the BPR NGK plugs by just replacing the older style wires and using the same rotor.  I suspect that most likely all combinations would work just fine on a well tuned car and you really wouldn't notice any difference.  I'm always wanting to learn though...

Edited April 4 by JohnS

[JohnS]

Sorry going a little off topic on the rotor questions.  I went digging in my crap to see if I had any of the e21 rotors.  None found.  Lots of the standard rotors with the 12111354503 part number.  The bonus was that I found a couple of the original tii rev-limiting rotors.  I wonder what the resistance is on those bad boys?  Any real reason to use a rev-limiting rotor on a stock tii driven by an old fart like myself?  Here's what I plan to install soon on my '74tii.  Rebuilt 002 distributor (from Advanced Distributors), Igniter II, and rev-limiting rotor.  Thoughts?  ...

 

Edited April 4 by JohnS

[tzei]

Measure R? You can always glue limiter non-operational. No reason not use limiter version unless it’s tired and limits too early or you would like to rev a bit higher.

[Son of Marty]

I don't like the hard rev limiters I mean if your running 6600 rpm do you turn your key on and off because that's how these rev limiters work. If you need a rev limiter your much better off IMO with a soft limiter that just shorts one plug at a time like the msd box.

['76mintgrün'02]

4 hours ago, JohnS said:

Sorry going a little off topic on the rotor questions.  I went digging in my crap to see if I had any of the e21 rotors.  None found.  Lots of the standard rotors with the 12111354503 part number.  The bonus was that I found a couple of the original tii rev-limiting rotors.  I wonder what the resistance is on those bad boys?  Any real reason to use a rev-limiting rotor on a stock tii driven by an old fart like myself?  Here's what I plan to install soon on my '74tii.  Rebuilt 002 distributor (from Advanced Distributors), Igniter II, and rev-limiting rotor.  Thoughts?  ...

 

I prefer the simplicity of the non-mechanized rotors.

 

The wide tipped one you showed looks like the one I'm using.  You can measure the resistance between the tip and center.  I'll bet that's a 1k ohm rotor.

 

I have not measured the bakelite plug wire ends' resistance.  I adjusted rotor resistance to keep the overall resistance close to the original design.  (I was told that it didn't matter which end of the run the resistance was on, plug or rotor).

 

Here is a link to some VW info, much of it also applies to our cars.  https://ratwell.com/technical/IgnitionSystem.html

 

This is from that.

Which Rotor?

If you have a Bosch distributor you should be using a Bosch or Beru rotor. They are the best made parts you can buy that are not only inexpensive but well made and long lasting. Only buy a rotor from the local auto parts chain in an emergency. Better yet, carry a Bosch/Beru spare.

If you have a stock ignition system your rotor is probably Bosch 04033 (or perhaps the 04016 rev limiting version). These rotors have an embedded 5 kohm resistor. The resistor serves several purposes:

• Limits current to reduce erosion of the spark plug electrode
• Reduce radio frequency interference (RFI)
• Works with coil to increase the burn duration of the spark
• Limit reverse current to protect the ignition switch

 

Keep an eye on the underside of the cap.  Sometimes there is an alignment problem with the 002 and Pertronix.  This was mine.  I called Pertronix and they recommended the model I used.  I think it was wrong. 

 

 

Sometimes the magnetic ring won't let the rotor sit low enough on the 002 and it rides hard up against the cap, so keep an eye on that too.  It's easy to see the problem because there'll be evidence of rubbing.

[Son of Marty]

1 hour ago, '76mintgrün'02 said:

If you have a Bosch distributor you should be using a Bosch or Beru rotor. They are the best made parts you can buy that are not only inexpensive but well made and long lasting. 

They were when they were made in Germany, but the off shore ones at least from Bosch have gone from good to beyond bad these days, which is a shame.

 

PS. I'm not saying the VW link above is in anyway diminished by Bosch's crap.

Edited April 5 by Son of Marty

[TobyB]

There's usually a number cast into the rotor- 5k or 1k.  Marelli was still good when Bosch went... south...

 

t

 

[JohnS]

Both of my cars have and are running just fine right now using stock 2002tii parts (I think Bosch or Beru) and an Igniter I for years.  Was going to "upgrade" to a rebuilt distributor using an Igniter II.  If it ain't broke don't fix it?  That's why I've been putting off this "upgrade" for over a year now...  The voice of reason is calling me... Don't f with it right now.  😊

 

I looked at both rotors with magnifying glass and don't see any indication of a resistance number cast into any of rotors I have Beru or Bosch.  I can see part numbers, production date circle...  What does the resistance code look like? 

 

Sounds like I don't need no stink'in  rev-limiting rotor.  I'll never hit those revs... 🙈

Edited April 5 by JohnS

['76mintgrün'02]

26 minutes ago, JohnS said:

What does the resistance code look like? 

 

 R5 example made in GERMANY.

 

I'm using the coil that was on the car when I bought it 12 years ago.  It's also marked GERMANY.

I also installed a used condenser that has GERMANY stamped in it.

 

I get a kick out of putting German made parts on my car.  It seems like these parts last a very long time.  My tune-ups have more to do with adjustment than replacement.   

[JohnS]

Found a NOS German made Bosch R5 rotor in my stash.  I'll use that along with some non-resisted NGKs that I have.  When I run out of the NGKs, I'll switch to Champion N9Ys.  Problem solved.  Thanks for all of the info...

 

['76mintgrün'02]

Nice!

 

Did you put a couple drops of oil under the felt plug inside the center post while you had the rotor off?

 

Is your cap marked GERMANY?