m103 spark plug gap...
 

Hey everyone! Just thought id let you guys know I installed new plugs today and have gapped them to .04, the car is running super smooth and I have had no problems whatsoever.

Re: m103 spark plug gap...
 

I'm curious about why?

I've always used the recommended Bosch copper plugs that are pre-gapped and I've never had any reason to think the engineers at M-B didn't know what they were doing. My 300E runs perfectly from idle to 6K.

the larger gap allows for a larger spark, thereby burning the fuel more completely, resulting in a smoother idle and a little more power. The reason MB didn't use the larger gap is probably due to operating tolerances. Can you imagine what would happen if mercedes started stalling out because of bad plug gaps? It would be disasterous to their reputation, and would be entirely possible if a car had a worn coil or perhaps sub-standard plugs were used. Big companies always have to be a little conservative with what they do, in order to make sure ALL of their cars run fine.

How many miles on your engine?

115,000

Thanks for the response. Have you actually noticed a difference?

In my case, a new set of ignition wires made a noticible difference even though I had no idea that the installed wires were damaged.

I only had about 50K on the clock when I changed the wires.

I change the plugs at around 20K because they cost practically nothing and are easy to change so long as I keep the wire boots lubed with HD silicon.

Well, the only difference I have noticed the is the smooth idle. The car has never idled this smooth before. As far as performance, the gains would be minimal, and probably not noticible to the seat o the pants meter...

Check out this thread:

http://www.peachparts.com/shopforum/tech-help/5999-spark-plug-gap.html?highlight=.040

Plug gaps
 

When owned my '89 190E 2.6 (another M103) a tech at my dealer told me they routinely used a plug gap of .035 which smoothed out the idle. Doing so eliminated a tremble at idle my car had.