proper spark plugs for Euro-spec M116 350SE?

[atatexan]

Is it the Bosch W7BC?

[djenka018]

Cannot remember 'bout Bosch, their price vs. quality was inhibitive for me.

For my 450 ROTW, I use NGK BP6ES and not a single atom of me ever regrets. Inexpensive and reliable. Should be the same for 350
For US specs, AFAIK, BP7ES is the way to go.

[ptashek]

Is it the Bosch W7BC?

I'm using NGK BP6E in my euro 450SE.

[atatexan]

Thanks all. Found out the proper plug is the Bosch W7DCO, a long life copper plug. Pierre Hedary and my father-in-law say the platinum plugs too hot for these cars.

[Casey]

Thanks all. Found out the proper plug is the Bosch W7DCO, a long life copper plug. Pierre Hedary and my father-in-law say the platinum plugs too hot for these cars.

Any ideas of proper Bosch plugs for the following?
* US-spec 450, D-jet
* US-spec 450, K-jet
* Euro-spec 6.9

One of the few issues with my '79 450SEL is that it will miss a fair bit when in gear at a stop once it's warmed up - I usually shift into neutral to avoid this.  I'm wondering if the plugs aren't a part of why.  As they don't cost all that much and the wires are old and brittle I'm thinking of just replacing all the plugs and wires regardless.  What are typical symptoms of bad/worn spark plugs on these cars?

People say diesels are complicated but I find getting proper spark to be much more so.  Diesels don't even need a battery or working glow plugs to run and I've push-started my manual 200D before.

[djenka018]

afaik, us spec cars use one step hotter plug. ffor ngk that's bp7e(s) and for bosch I thinkk number goes down I.e. w6

[ptashek]

What are typical symptoms of bad/worn spark plugs on these cars?

Same as on any petrol engine - very rough idle if a few of them are weak or don't fire at all, a lot of fouling, damaged or burned out electrodes, decreased mileage, and the tell-tale smell of unburned fuel out the tailpipe.

[Tony66_au]

I run NGK BP6ES in the K jet and BPR6EIX Iridium in the D jet 450, I originally used Bosch plugs supplied with the car when i bought it and they were ok but I was given the iridium plugs by a rep and they make a noticeable difference to both performance and acceleration.

[s class]

I used Bosch W7DC in all euro W123/107/116/126.  They are cheap here in South Africa at about $2 each. 

[djenka018]

How much are NGK's in South Africa now?

During my life in RSA, they were so affordable for my daily driver that I had them replaced every 10000km service.

[ptashek]

I've been changing plugs in my 450SE today, and I'm happy to have done so. Turns out she was running on 7 cylinders (idle was a bit rough, but just). Now that I know why, I consider myself to be lucky as heck... At least one thing this week ended well. Now that she's running proper on all eight cylinders, the rough(ish) idle is gone and acceleration is smoother as well. I guess mileage may improve as well, although 17l/100km on average isn't that bad.

I sure won't be buying Bosch sparks anytime soon. This is how one of the W7DCs came out the cylinder head...
It may have been overtightened, but to me this looks more like a material defect.

[jbrasile]

I have become an NGK fan over the years. BP6-ES is the spec for basisally all Euro applications both 6 and 8 cylinder. US cars up to 79 use BP6-ES and BP5-S for 1980 onwards with O2 sensors. With NGK and Bosch, the lower the number the hotter the plug, Champions are reversed.

Tks

Joe

[jbrasile]

Casey,

The miss at idle on the 450SEL is probably caused by one or more bad igntion wires or maybe a tired coil, pretty easy and inexpensive to fix.

Tks,

Joe

[atatexan]

The M-B tech father-in-law suggested we had the idle a tad high so that at rest, in gear, it seemed to miss. He said idle was high engough, though below 900RPM's, that the engine's little brain shuttled back and forth between thyinking it was to accelerate then stop. Sure enough I dialed down the idle and the miss went away.

If only everything else were so simple.

[carzilike]

Hi all, is anyone able to confirm which plug to go with for a 1976 280SE (Euro Spec) D-jet? I am finding too much variation in what is being suggested by parts websites like Rockauto