Best Sparkplugs for 1967 230SL M127 motor

[Benz Dr.]

All I see here is Pertronix employing CYA. Carbon core wires are bad advice for our cars.

A 560SL uses metal core wires, electronic ignition, and a fairly hot coil which works just fine on those cars.

 6K ohms total system resistance is optimal for our cars. 5K for the rotor and 1K for the spark plug ends. Resistors are used for radio suppression, AM radio, and few listen to that anymore. Aside from the farm report ( important ) or talk radio ( not very important )

[67230SL-Vinny]

It would seem that if the solid core wires in your W113 are in good condition, and the engine isn't soaking wet like a tractor might be, I would think there's no reason to switch to carbon core wires if using the Pertronix ignition.

However, I'm still not sure about whether the idle is smoother with R plugs.  I'm thinking Bud's, very experienced with Pertronix installations, installed WR7DC plugs for a reason. I should have my answer next week.

[Paul99]

I get my plugs from THE GREEN SPARK PLUG COMPANY in the uk.

https://www.gsparkplug.com/ignition/spark-plugs

https://www.gsparkplug.com/catalogsearch/result/?q=NGK+BP5ES+6511+Spark+Plug+Copper+Core

A small UK family run company so I am sure they will ship anywhere (postage costs I guess) 

Hope that helps my USA Canada cousins.

[CFF]

FYI in the US the Mercedes classic center has the proper none resistor Bosch plugs. I think I paid $5 each for 18 of them so I have some spares.

I believe Mercedes is the only source for the correct plugs.

[Tomnistuff]

Is there an easy-to-decipher chart or charts explaining available heat ranges and cross-referenced equivalances for some of the more reputable spark plug company's products? 
They all seem to have different numbering systems and lots of wonderful claims but no technically useful information or comparisons.
Tom Kizer

[67230SL-Vinny]

Quick Update:
Bud's confirmed that the only reason they used the WR7DC plugs with the Pertronix back in 2015 when they installed it was because the W7DC plugs were NLA. If they could have still gotten them at the time they would have used the W7DC originals. So the Pertronix doesn't change what plug should be used.

The good news.....Bosch apparently made the replacement for the original, now called W7DC0
Not sure where my mechanic got them but....Just Google the new number W7DC0 and you'll find them.

I did a test replacing the WR7DC with the W7DC0 and in fact the new plug did run smoother and stronger, like the original!

Get 'em while they're hot! 

[Ed Riefstahl]

Greetings fellow Pagoda friends,
I could also use some direction here in the area of plugs and wires. I've been reading this thread with great interest, but may have missed something. As some of you know, my wife and I are planning a 5-7000 mile road trip this summer in our 1966 230SL.

I have changed the oil in the injection pump and adjusted the valves. One of the last things on my list is cap, rotor, plugs and wires. I think they have about 25,000 mile on them. I,m currently running Bosch WR9DC plugs & and standard Bosch wires.

I pulled one of the plugs this morning and they need to be replaced. Even after following this thread, I am still unsure what plugs to put in the car. I may be able to get the above plugs, but am wondering if there is a better option and if I should try to get non-resister plugs.

The compression is not great and in about 125 to 130lb range. I believer my 280S is above 150. So I'd like to do whatever I can to get the best performance I can before our trip over the Rockies. A complete engine rebuild with be in order down the road, but it runs great, uses no oil.

I think I can make a solid wire core coil wire easy enough, but what plugs should I try to get for it? Maybe I'm missing something, but still not sure what plugs will perform the best, that are available and if non-resistor will help.

I appreciate any and all suggestions or comments.

Ed Riefstahl
1966 230SL (Ms Magoo)
1970 280S (Miss Daisy)
1999 BMW Z3 5 speed
1991 BMW 318I 5 Speed
1997 Toyota Paseo Convertible - One of 1000, (have you ever seen one?)
1997 Ford Ranger step side (Mater)
2023 Mazda CX 5

[Pawel66]

You may want to take a look at the enclosed. I thought I saved it once in Technical Manual, but cannot find it there now.

From a non-mechanic perspective, I would not experiment going for a long-haul trip. If I had solutions that worked for me, I would probably stay with them.

[BobH]

You may want to take a look at the enclosed. I thought I saved it once in Technical Manual, but cannot find it there now.

From a non-mechanic perspective, I would not experiment going for a long-haul trip. If I had solutions that worked for me, I would probably stay with them.

That's a handy document Pawel, i've added it to the "ignition system" and the "123" section of the manual

Thanks

[TJMart]

You may want to take a look at the enclosed. I thought I saved it once in Technical Manual, but cannot find it there now.

From a non-mechanic perspective, I would not experiment going for a long-haul trip. If I had solutions that worked for me, I would probably stay with them.

Pawel,

That's a nice summary! Is there one for a 280SL WITH transistorized?

Tony

[Pawel66]

No, I am sorry, I was selfish, did not go to the transistorized version...

[mauro12]

Hi guys , I’ve always used Bp5es but I noticed that often I have interference with the radio . Some strange noise that increases with rpm increase. I’m almost sure that depends on the no R on the plugs . Have you experienced the same issue ?

[Benz Dr.]

Hi guys , I’ve always used Bp5es but I noticed that often I have interference with the radio . Some strange noise that increases with rpm increase. I’m almost sure that depends on the no R on the plugs . Have you experienced the same issue ?

AM radio?

[mauro12]

I guess should be fm frequency . Am is not used anymore .
What difference it makes ?

[Benz Dr.]

AM will pick up a lot more radio waves from the ignition system. Later high output ignition systems need resistor wires and plugs to protect the ignition boxes from radio waves. Our cars really don't need much resistance in the ignition system.