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420 SEL
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Discussion Starter · #1 ·
Help, I want to find a plug that works in my 420 SEL, I just installed a new set of Bosch super WR8DCW plugs and the car ran fine for a day or so. I went to run it this morning and it was shaking like a bag of crap and wouldn't even drive off. I pulled the plugs and they were black, one of them was completely dead, no spark at all. I put in one of my old plugs, cleaned the others and it now runs fine. The temp here is cold, in the teens at night and I don't know if these temps need another temp range of plug or not. Advice is appreciated.
Rod...[:(]
 

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Depends on the day!
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JDC is correct.. Don't mess w/ the plugs on these cars, run what the factory recomends.


Jonathan
 

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420 SEL
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Discussion Starter · #4 ·
Thanks for the info, I agree and today I ordered a set of W8DC0 plugs, hope these do the trick.......[^]
 

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Discussion Starter · #5 ·
Fitted my new original spec spark plugs and the car runs as good as new, no stumbling or rough idle and it runs smooth and strong, I just hope it stays this way...[:)]
 

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1985 380SE
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Earlier posts suggested Bosch H9DCO plugs...

" gap them to .032� or .8 mm – 28nm torque. This is the same value for all 126 V8s and the M103. "

What is the difference, besides heat range?
 
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