Brett San Diego

I specifically ordered spark plugs for my 1978 911SC from Pelicanparts.com since they were listed as W8DC. I would have just added plugs to my order of the rest of my scheduled maintenance goodies from www.autohausaz.com, but the plugs there were listed as the WR8DC plugs. So, I went out of my way to place a separate order with Pelicanparts.com since the experts recommend the W8DC model. I get the spark plugs in the mail, and they are WR8DC (labelled on each individual spark plug box and on the larger Bosch packaging containing 10 plugs). But, stuck on the outside of the box is pelicanparts.com's own label saying W8DC.

So, was Pelicanparts just careless here, or is there really no difference so that they sell the R and non-R plugs interchangably? By "no difference," I mean in using one versus the other in reality. I understand the difference in plug construction with resistors in the R plugs.

Thanks for your comments,
Brett

theiceman

hmm..... better go down and check my plugs.... :-)

Peter Zimmermann

Hi Brett: Bosch has recently introduced a new and improved line of spark plugs that incorporate a rare earth element called Yttrium in the center electrode, and in the ground electrode when Bosch considers it necessary. The WR8DC does replace the W8DC, according to Bosch, "with no performance disadvantages." Apparently Bosch has discovered that a single electrode plug with yttrium will match or exceed the life expectancy of a copper core multi-electrode (created to extend service life) plug. I guess we all have to try them, the same updates have been done to the W5DC and W7DC plugs, as well as many others. Pelican has probably opted to not change their labeling system because the update is a Bosch factory authorized change.

Brett San Diego

Thanks, Peter. Said like a crotchety old man, "Well, I'll use 'em, but I ain't gonna like it."

Actually, I'm more bummed that I paid 80 cents more per plug plus extra shipping from Pelican for something that wasn't what they said.

Brett

theiceman

Today I changed my plugs becaue i was bored and decided to dig in tt why i keep ordering plugs and now have 4 different sets of plugs on my shelf. Found Brett's post here and got my questions answerd but found this cool document i thought i would post .

Page 11 and 12 gives a great decoding of te numbers on the plugs if you are inteested.

BTW I am running the "R" plug now and took out the non R plugs. They looked absolutely perfect when i took em out , in fact they looked so good if I were a spark plug I would " hit it "

http://www.bosch.com.au/content/lang...Sect_Spark.pdf

User 4221

IIRC, "R" plugs are resistor type and emit less electrical noise to stuff like radios, etc. They should function fine.

theiceman

Yes that is right Scott all new plugs are "r" plugs now. I wouldn't want electrical noise interfering with my CIS now would I

BTW no good deed goes unpunished . Last night I went to go for a ride and test it out but it ran like a bag of dirt as soon as I started it. sounded like it was missing a cylinder, Been here before ...
Went to bed as i was tired.
This morning i tried to start it again , same problem , so I decided to back track my steps, all connectors and leads were firmly in place so i decide to undo my project, changed the passenger side bank back to the old ones .. tried to start it ...same problem ..
Changed number one as it was a bit of a pig, then I changed the middle one , then I changed drivers side front. As soon as I took it out i noticed the gap on the plug was completely closed. I must have dropped it and not realized it after checking initial gap ..... bit of a relief really. All is great now . I am back on my original plugs , runs great and I have a ton more experience at changing plugs now .
I am off to buy a lottery ticket as only i could check 6 plugs and have it be the 6th one that i check be bad

Edgy01

Usually we cause collateral damage when so do a good deed--glad you spotted the problem so quickly.

whalebird

Good find Ice. I have said that warking on a 911 requires that you do everything twice...the first time around. Valave adjustment is the same - after the second time, you get the gist of it.
In regards to plugs, many will slather the plug in anti-seize and dielectric grease only to cause problems.
Plugs like to be "dry", although some will say that you should anti-sieze the upper half of the plug threads, or the bottom half yadda yadda yadda. I always install them dry and only tighten them to the point you feel the new seal ring squish. Starting them by hand is very important, it may help to put a piece of rubber fuel line over the ceramic as an "extension" to reach them into the head.

theiceman

Whale that is why I like the factory tool from my kit .. it he a "Knurled " sp? **** at the top so you can screw them in by hand which is great .. as soon as I feel it stop it is only another 1/4 turn with the wrench and I am set.
I thought i read somewhere that plugs now already have a coating on the threads to help them go in easier .. but maybe I just dreamed that part..
But I learned a lesson here .. next time i have a suspect plug I am taking out that one first

whalebird

I have always found the factory tool to work best. I have a collection of spark plug sockets from snap-on etc, which are pretty good, but cheaper ones can wobble a bit and you can crack the ceramic while tightening the plug, or removing.
Evena though the new plugs come pre gapped, it's good practice to check them before install.

theiceman

...or after you drop them