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Old 03-07-2000, 11:04 AM
Posts: n/a

Hi Nick,
I've been steering people away from the "mass-market" (tiny electrode) platinums since I tried them 10 years ago.I have no problems with the real Platinum plugs ($18.00+ each)that Bosch has made for Porsches for eons(other than the cost/benefit). The problem with the cheap Platinum plugs is the small size of the center electrode and the fact that since it doesn't have enough rigidity to support itself,it can't protrude beyond the end of the insulator. In cars that run a relatively rich fuel mixture the plugs tend to arc down the center insulator to the shell. In a test chamber (an old Champion Spark Plug cleaner/tester)using compressed air to simulate conditions in the engine,the difference between the Platinum plugs and standard Copper-Core is obvious. The Platinum plugs produce a very thin thread of spark compared to the copper-core plugs. The spark plug's mission is to initiate combustion. A "fat" spark hits more molecules of the hydrocarbon/air mixture than a thin spark.The more molecules that are "hit" with the spark,the more efficient the combustion process. Try going back to the standard plugs gapped to 1.0 mm (.040")and see if the idle and acceleration "feel" better. The consensus among Techs (from empirical data)is that copper works best in a Mercedes.
Randy D.

ASE Master Tech
Mercedes Tech 20 Years
68 250SE
68 SAAB 96 Ice Racer
69 300SEL 6.3
70 300SEL 3.5
81 300TDT
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