TheSamba.com :: View topic - Hate to ask

Sun Sep 12, 2010 1:10 pm

I bought some plugs about 6 months ago and put em on the shelf due to a long body work project. Now I am tuning up and thought I would change out the plugs while I was at it. I have been running what was in it when I bought the car - they are Bosch WR8BC+. The new ones I bought at Autozone are WR8AC+ plugs (7902 new numbers). I did a search and I see a bunch of references to the 7902, but not to the "B" plug that is in my car now??? I looked on the bosch site and it seems there is some difference and I compared them - the ceramic extends out further on the "B" plugs in my car than the "A"...

So, can i run the 7902?? I think someone is going to pop on and say it depends on the 1/2" reach or 3/4" reach of my heads - what does that mean and how do I find out???

I want to nail down ONE source for plugs and stick with it, so if I need to just go buy something else I will - even the NGK's if that is best (though I think the reach thing on the heads applies there as well - B6HS vs B5HS??)

Again, I have a feeling I am about to open an opinionated can of worms on this one, but oh well, I want the right thing.

Sun Sep 12, 2010 2:07 pm

No can of worms yeat ....have you checked crossreference on the plugs ?I would call the store where you bought them from and find out if those are the righ plugs ,or if u still have the receipt go and exchange them for some ngk if that's your personal choice ..

Sun Sep 12, 2010 2:23 pm

Please let us know the specifics on your year and engine. For MOST classic VW's the Bosch Super Plus (7902) is the right choice, but if your running any engine mods this may not be the plug for you.

Alot of folks have been worried about the difference between the old Bosch Supers that we ran for years and the new Super PLUS. Bosch no longer makes the old Super, and have replaced them with the super plus. It has a resistor in it which is better for modern stereo equipment, and has a fancy metal called Yttrium, which is supposed to last longer.

I have been running the 7902 super plusses in all 3 of my daily drivers for over a year now with nothing but good things to say about them.

There will always be people that are as passionate about thier sparks plugs as they are about thier cars. Some will stand behind NGK or autolite etc etc etc. My personal preferance has always been the Bosch. German plug for the german engine. In my vintage japanese motorcycle I use A japanese plug. It just makes sense to me that way.

The most important thing is to make sure the plug has the correct reach, and the correct heat range.

If you lay the new plugs side by side with the old ones on a table, and the metal part that screws into the engine looks the same then you have the correct reach. Heat range is a bit more complex, but like I mentioned above.... without the specifics on your engine no-one can really help you there...lol. Chances are if the 7902 is the correct plug, unless your running mofified engine components or specialty fuels.

Sun Sep 12, 2010 2:23 pm

I believe that the WR8BC plug has an extended electrode as compared to the WR8AC. It shouldn't cause any problems.

Here is Bosch's chart:

http://www.boschautoparts.com/Technical%20Resources/Spark%20Plugs/SuperPlus_DesignationCodes_10.pdf

Personal opinion follows:

After chasing random quality with Bosch plugs for a while I finally switched to NGK. They were OEM on my Meximotors and have kept consistent quality.

BP5ES for long reach applications, BP5HS for short reach. Add an "R" before the number if you want resistors.

Here's NGK's chart:

http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf

Sun Sep 12, 2010 8:30 pm

That helps. As far as what I have - it is a 73 Super that is stock. Nothing fancy, just a daily driver.

From what I gather then, the 7902 Bosch will do just fine.

Thanks for all the input.

Sun Sep 12, 2010 9:05 pm

As far as the W8AC Bosch I wont argue that for stock Bugg 1600cc etc.
Best plug ever , just cant get them no more !
But NGK Im told is the way to go .
But I too worry about plugg depth in the Head as well as the fact that Bugg's are notorious for spittin plugg's out .
In Olden day's it was beleived that a lott of spitt out plugg's were due to Plug hole thread damage primarily attributed to runnin Champion plug's in place of the Bosch .
It was beleived that thread pitch / tapper was different from American to Japp to German .
On dirt bike's I still beleive there was some truth to this ?
But over the year's it has become a more customary beleif that changeing plugg's out on Hott motor's and over torqueing were considerd the more probable cause of spit out plugg's / cracked head's between Plugg hole and valve seat etc.
Never change the plugg's out on a Hott motor !
But in half inch reach thread plugg's NGK B6HS or the NGK B5HS is fine wich plugg to use is directly related to CCR and some claim Hemi cutt also affect burn and should be considerd when chooseing the Hotter or colder Plugg .
Plug reach is how long thread's are either 1/2 inch or 3/4 ( Can look at top of plugg hole to see if 1/2 in or 3/4 is needed 1/2 in reach will have reccessed plugg hole and 3/4 will be almost flush on plugg hole )
Hotter Plugg's have smaller diameter Electrode etc .
As to the Copper coated electrode WR8AC < my understanding is that this plugg is the reccomended replacement by Bosch, for the W8AC.
But that most experienced A.C. V.W. mech's do not reccomend this plug all tho at the moment I seem unable to re- call exactly why ?
Argghhhhh ? Complete blank ! LMAO
Maybe some one else know's ?

Fri Sep 16, 2011 11:22 am

GeorgeL wrote: I believe that the WR8BC plug has an extended electrode as compared to the WR8AC. It shouldn't cause any problems.

Here is Bosch's chart:

http://www.boschautoparts.com/Technical%20Resources/Spark%20Plugs/SuperPlus_DesignationCodes_10.pdf

Personal opinion follows:

After chasing random quality with Bosch plugs for a while I finally switched to NGK. They were OEM on my Meximotors and have kept consistent quality.

BP5ES for long reach applications, BP5HS for short reach. Add an "R" before the number if you want resistors.

Here's NGK's chart:

http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf

The BP5HS has a different tip then the stock plugs. Does that mean I need to get a different set of wires?

Fri Sep 16, 2011 1:19 pm

HI72 wrote: The BP5HS has a different tip then the stock plugs. Does that mean I need to get a different set of wires?

You mean on the end that connects to the spark plug wires? The little round ends on the spark plugs simply unscrew, use a Vise-grip pliers.

Fri Sep 16, 2011 10:54 pm

i wouldn't go with NGK B5HS for a 1600. Today i noticed my car sounded like it was running off of two cylinders, so i pull my distributor wires and that was exactly what was wrong with it. I pulled the plugs out and did a compression test and my compression was fine. The one thing i did notice was my spark plugs on the two cylinders looked different from the ones that were firing correctly so that has to be the problem, so tomorrow im going back to good old bosh. :)

Thu Sep 29, 2011 1:18 pm

PinetreeKiller68 wrote: i wouldn't go with NGK B5HS for a 1600. Today i noticed my car sounded like it was running off of two cylinders, so i pull my distributor wires and that was exactly what was wrong with it. I pulled the plugs out and did a compression test and my compression was fine. The one thing i did notice was my spark plugs on the two cylinders looked different from the ones that were firing correctly so that has to be the problem, so tomorrow im going back to good old bosh. :)

Hmm, in what way do they look different? Could you have a vacuum leak on one side? I can see one plug showing a defect, but not two.

NGK plugs are very consistent in quality, the way that Bosch plugs used to be before they moved production to 3rd world countries.

Thu Sep 29, 2011 4:34 pm

GeorgeL wrote:
Personal opinion follows:

After chasing random quality with Bosch plugs for a while I finally switched to NGK. They were OEM on my Meximotors and have kept consistent quality.

BP5ES for long reach applications, BP5HS for short reach. Add an "R" before the number if you want resistors.

Here's NGK's chart:

http://www.ngksparkplugs.com/docs/tech/partnumberkey.pdf
^^ agree 100%. bosch plugs just aren't what they used to be. quality control is way down. i switched to ngk for both my beetle and my 911 and had no problems since.

i use ngk bp6hs in the beetle w/ stock 1600dp & stock vw heads. runs beautifully. i've got almost 10,000 miles on them right now, runs like a top still.

Thu Sep 29, 2011 4:36 pm

PinetreeKiller68 wrote: i wouldn't go with NGK B5HS for a 1600. Today i noticed my car sounded like it was running off of two cylinders, so i pull my distributor wires and that was exactly what was wrong with it. I pulled the plugs out and did a compression test and my compression was fine. The one thing i did notice was my spark plugs on the two cylinders looked different from the ones that were firing correctly so that has to be the problem, so tomorrow im going back to good old bosh. :)
are you sure you had the firing order right? 3 and 4 are easy to mix up. trust me i know... happens to the best of us at one time or another. :lol:

Thu Sep 29, 2011 4:58 pm

also check what kind of heads you've got. i think some aftermarket heads use 3/4" reach spark plugs, in which case you'd need the -es ngk plugs instead of -hs.