Spark Plug Question for a 1969 280SL

[Rolf-Dieter ✝︎]

While in Germany last month I picked up 6 new spark plugs for my car.

I am wondering if they gave me the right NGK plugs for my car having the original ignition.

The new plugs i have are 2412 NGK BP7ES

Also, what Spark Plugs are you using?

Thanks,

Dieter

Edit Typo ... read NGK BT7ES ,,, should have read 2412 BP7ES NGK

[Jowe]

BP7ES, or equivalent, are the original spec. However, if your engine runs rich (which propably most are), slightly hotter plugs are better. I changed from BP7ES to BP5ES earlier this year and my engine runs much better after that.

[66andBlue]

Sorry Dieter, wrong plug! The "R" stands for "resistor" and you do not want that.
Download the PDF it is more readable.

[Rolf-Dieter ✝︎]

Thank you Johan and Alfred,

I had a typo "T" instead of "P" (I made the change in my original post) I will try the plugs for a while and see how they work for me. My plugs have not been changed in the past 4 years and 10,000 plus miles.

Thanks again for the quick reply !

Dieter

[Benz Dr.]

BP7ES, or equivalent, are the original spec. However, if your engine runs rich (which propably most are), slightly hotter plugs are better. I changed from BP7ES to BP5ES earlier this year and my engine runs much better after that.

And that's why it's the only plug I recommend.

[WRe]

Hi,
here you can find some info and checklists for the different spark plugs:
- http://www.gs-classic.de/download/ZuendkerzenVergleich01.pdf
- http://up.picr.de/4489147.pdf
- http://www.christian-koerkel.de/Service/Zndkerzen.pdf
- http://www.tmoc.de/fileadmin/upload/office/Zuendkerzen.pdf
- http://www.judweggis.ch/pdf/Zuendkerzenliste.pdf
...WRe

[Rolf-Dieter ✝︎]

Thank you One and All for the information

Dieter

PS ... Just for reference, I removed the old plugs and they are BOSH SUPER PLUS WR7DC Brasil 790

[Cees Klumper]

Inspired by this thread I checked my plugs and found I am using NGK BP7ES. I had a set of BP6ES as spare, but no '5s'. So I went and ordered thru Amazon 12 of the '5s' and found wildly different prices, from €1.75 each to €10 or more. They're on their way and I look forward to trying them out, as I believe my car does run a little rich (need to get myself to order and install that wideband air-fuel gauge one day).

[mdsalemi]

Inspired by this thread I checked my plugs and found I am using NGK BP7ES. I had a set of BP6ES as spare, but no '5s'. So I went and ordered thru Amazon 12 of the '5s' and found wildly different prices

Wildly different prices on Amazon is the rule. Usually for most everything, there's a tight band, and then the outliers.
I'll agree with Jowe on the BP5ES. I had the "6" for years, but Dr. Benz suggested the 5's, and it does run better with them, I think a cleaner burn.

[Rolf-Dieter ✝︎]

Perhaps we can describe some of the symptoms we see when we say "Running too Rich or too Lean"

When I make a quick research on the Internet on "Running too Rich or too Lean"

I come across this link ---> http://automedicsafrica.com/car-running-rich-lean-means-much-insufficient-fuel-supply/

So my question(s) to you Gentleman is "On what symptom do you base if your engine is running too rich or to lean?"

a) build up on your spark plugs.

b) engine temperature.

c) smell of gasoline as you drive.

d) plugged fuel injectors.

e) faulty air flow sensor.

f) all of the above.

I purchased my spark plugs from a very reliable source in Germany a dealership that maintains Pagodas all the time. I requested plugs for my 280 sl and was given the 2412 BP7ES NGK plugs. Can it be that in Europe they use the original specified spark plugs and in our part of the world we change spark plugs to a different specification while perhaps ignoring points "d and e" above as being the route cause. I wonder.

The spark plugs I removed do not look too bad (compared what Ive seen in the past on some of my American cars that Ive owned over the years), so I will monitor the spark plugs now in place as to build up and condition as well as behaviour of my engine during sort and long trips.

Dieter   

[Cees Klumper]

My main clue is that my engine has always consumed a lot of gasoline ... even after the total rebuild by Joe in 2003 (in fact it was a different engine) the fuel consumption did not improve. Probably because I am running the same fuel injection pump. I have set the idle mixture (including by using a Gunson CO meter) so that is fine, and the split-linkage test is ok, the cold start valve does not leak and so on and so forth, but as we know checking and adjusting the mixture under load is a different matter; not so easy. That's why I know I need to either send off the fuel injection pump, install one of the other 10 or so that I have sitting around idle (pun intended) OR get a wideband air/fuel meter to see if I can calibrate the pump under load settings.
Other than that, the engine runs fine, the plugs don't foul up, and I have no other obvious symptoms of overly rich mixture other than in stop-and-go traffic the engine has run a little warm on two occassions (in 18 years ...) but as we know that can be due to a host of other issues with the cooling system.

[Benz Dr.]

I go by '' Pin Ball Wizard '' senses.  How the engine idles, what it smells like, what color the plugs run at, how it sounds, and how well it pulls under load. Pretty hard to beat a seat of your pants feel. Either your car has it, or it doesn't.

[Rolf-Dieter ✝︎]

Well Dan,

You have driven my car and I've driven yours and I think we both can agree our cars do have it

BTW, like you I also go by what I see, feel, smell etc. One reason I gave up my ///M3 (e92) since it had no dip stick for me to see, feel or smell my motor oil

Mind you my car has a few signs of old age and I do my best to correct that as time goes on. Notting too serious and quite forgiving considering the age.

Dieter

[Iconic]

Why are you all only talking about NGK plugs?
What is wrong with the Bosch spark plugs, specifically the WR7DC+ (7900)?

[Jowe]

Why are you all only talking about NGK plugs?
What is wrong with the Bosch spark plugs, specifically the WR7DC+ (7900)?

The recommendstion is to never use plugs with additional resistance e.g. WR7DC. Bosch W7DC and NGK BP6ES are equivalents and W8ES and PB5ES are equivalents. (Yes, higher number on Bosch are hotter, whilst lower number on NGKs are hotter...) Also Champion plugs may work, N11YC or N13YC are similar to BP5ES.

Have a look in the Service and Maintenance Manual in the Premium section about spark plugs.

[Rolf-Dieter ✝︎]

Why are you all only talking about NGK plugs?
What is wrong with the Bosch spark plugs, specifically the WR7DC+ (7900)?

The discussion is about the NGK BP7ES plugs since (see original post) I purchased those plugs in Germany last month during my Euro trip and was given those plugs for my 280sl by the owner of a shop where Pagoda's are serviced and restored.

There is nothing wrong with the BOSCH (Super plus) WR7DC Plug, I had those in my car for the past 4 years (driven 10,000+ miles and they still look great). I replaced (for the time being the BOSCH plugs with the NGK plugs). I will check them once I arrive at PUB in September and compare them with the WR7DC plugs. Another member here will bring me the NGK BP5ES plugs and I will then replace the NGK BP7ES plugs with the NGK BP5ES plugs.

I will make it a test (driving to PUB with the NGK 7's and returning back home the same distance with the NGK 5's) and see what difference there will be in a) gas consumption, b) behaviour of my engine and how the plugs look as far as deposits are concerned. 

I'll report my findings here after PUB

Dieter

[Iconic]

Also, what Spark Plugs are you using?

OK Dieter. But I was referring to your question above and I was surprised no one was talking about the Bosch plugs.
Even you mentioned that you took out the Bosch spark plugs and are replacing them with NGK.
I am using Bosch WR7DC+ (7900).
I look forward to hearing your test results.

Dan, why don't you use the Bosch spark plugs?

[Benz Dr.]

Anything with an R in the code indicates a resistor plug and the thing you want is actually remove as much resistance as possible. I kook for and remove carbon core wires, 1K ohm resistors on plug wires at the distributor cap or coil wire and resistor plugs. The rotor will have 5K ohms and spark plug terminals should have 1K ohm for an optimal system.

I used to use Bosch plugs. W9DC was my choice but they'e no longer easily available and that's an important when trying to move work along. The equivalent plug in NGK is BP5ES and I find they may even work a little bit better. I refuse to use Champion or AC plugs in an aluminium head. Black oxide and zinc plating have nothing on nickel when it comes to anti corrosion and Bosch or NGK are nickel plated. I still use a dab of anti seize on every new plug.

As an aside:

AC stands for '' Alfred Champion. ''

[stickandrudderman]

I usually fit WR7DCO without problems.
Occasionally I can find some W7DC old stock which I'll buy and use but it doesn't seem to make any difference.

[Benz Dr.]

Some engines will run OK on cooler plugs and some won't. It could be fuel additives or maybe it's simply 50 years worth of service required. 

[Iconic]

Thank you Dan and Stick !!

[66andBlue]

....  Black oxide and zinc plating have nothing on nickel when it comes to anti corrosion and Bosch or NGK are nickel plated. I still use a dab of anti seize on every new plug.

For someone with as much experience as Dan has using anti-seize may not lead to over tightening the plug and damaging the thread.

But NGK warns against using anti-seize because it may lead to over-tightening . See PDF in the tech manual: https://www.sl113.org/wiki/Electrical/SparkPlugs
NGK plugs are surface treated with Zn-chromate to prevent corrosion and seizure.