Non resistor spark plugs
 

Hello,

If anybody is in need of non-resistor spark plug for your mercedes I have just ordered some from BERU. Here is the link, $3 each..................
US Distributor of genuine BERU products -http://www.beruparts.com

They are located in San Marcos California and the Tel# is 800-643-0375

They had to order from Germany but are listed in their stock as current and available.

My handbook for the Mercedes 300ce/m103/w124/1989 says I need the following plugs in my car..........
1]Bosch H9DC, H9DCO, or H9DP
2]Beru 14K-9DU, 14K-9DUO, or 14K-9DPU
3]Champion S12YC, or S12YCC

Good luck::D

Gavinbr

There are still some vendors with new old stock Bosch on the shelf. I got a set last Spring. Probably should have bought two sets.

Just google HD9CO or whichever you are looking for.

Resistor plugs
 

I have seen reference to not using resistor plugs before. The dealer has always given me I believe hr9dco plugs resistor. I change them about every 30k. Is there a reason not to use resistor plugs?

Because they are out of the non-resistor ones.

Denso T20EPU are a great alternative too.

I will get iridiums for Christmas

the additional resistance of the R -type plug causes performance and idling problems ,not so apparent till you install the correct non- R plugs
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Are they more that about 2 or 3 $ or € each? If so, save the money and spend it on Christmas drink.

And no resistor types either, I hope.

R

I don't have the part number on hand but on all the vintage stuff we work on we use NGK non-resistor plugs, had great luck with them and they are easy to find.

IIRC its BP5ES and BP6ES.

I need iridiums with my nitrous

Yep, that's what I use.

M103-12V uses the NGK BP5EFS

The 6 is a step colder then the 5...
NGK is counter intuitive in their heat range numbering...higher the number, the colder the plug.
Also have the out of production Beru S1K non resistor solid silver electrode plugs that I will be trying out in place of the NGK's...

I have changed plugs in my M103 many times, but I also am getting old enough that my memory is not serving me well.

I remember 10 or 12 years ago Benzmac (Donnie) recommending the Bosch plug and closing the gap a little tighter than the factory spec. I have done that with every plug change since that time and it improved idle quality and general performance. Now, however, I can't remember how tight. I THINK I've set them at .032" but I don't remember for sure.

Even though I'm old, I still have a great memory. Problem is that it's kind of short.:rolleyes:

I'm also old in my 60's.....your .032" or .80MM gap is just fine ;)

From NGK:

3. Gapping
Since the gap size has a direct affect on the spark plug's tip temperature and on the voltage necessary to ionize (light) the air/fuel mixture, careful attention is required.
While it is a popular misconception that plugs are pre-gapped from the factory, the fact remains that the gap must be adjusted for the vehicle that the spark plug is intended for.
Those with modified engines must remember that a modified engine with higher compression or forced induction will typically require a smaller gap settings (to ensure ignitability in these denser air/fuel mixtures).
As a rule, the more power you are making, the smaller the gap you will need.

A spark plug's voltage requirement is directly proportionate to the gap size. The larger the gap, the more voltage is needed to bridge the gap. Most experienced tuners know that opening gaps up to present a larger spark to the air/fuel mixture maximizes burn efficiency. It is for this reason that most racers add high power ignition systems. The added power allows them to open the gap yet still provide a strong spark.
With this mind, many think the larger the gap the better. In fact, some aftermarket ignition systems boast that their systems can tolerate gaps that are extreme. Be wary of such claims. In most cases, the largest gap you can run may still be smaller than you think

http://www.ngksparkplugs.com/techinfo/spark_plugs/installation.asp

Nice write up on gapping,I had wondered why NOS said to close the gap to .030