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Always Remembered RIP
1991 560SEC AMG
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10,146 Posts
Discussion Starter #1
Resistor or non-resistor?

I bought a set of OEM Bosch plugs (made in Germany) but forgot to specify?

Which type are best - and preferred?

I have never tuned up a 420 engine before. I already have the distributor caps and new plug wires, and am otherwise set to go. (Tomorrow morning)

Thanks
 

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Banned
1993 400E
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7,361 Posts
Copper core, NON resistor.

Bosch F8DC4 or Beru 14F-8DU4

There are Denso plugs that cross reference, use the
above numbers.

I prefer Bosch.

Are the plug wires copper core? If not get a set of Karlyn STI wires.
They make the OEM wire sets for Benz.
 

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Registered
1992 400E Nautical Blue/Andoor Blue/Creme Beige 267,000 miles
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56 Posts
I prefer Bosch F8DC4 as well. Also I only use Bosch distributor caps and rotors. The M119 tends to go through these more rapidly than the other engines. When I tuned mine up, I crossed my plug wires over top of each other, and it ran rough. As soon as I straightened them out, parallel to each other, it ran great. Of course this is not a scientific test, but it seemed to make a big difference.
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,468 Posts
I prefer Bosch F8DC4 as well. Also I only use Bosch distributor caps and rotors. The M119 tends to go through these more rapidly than the other engines. When I tuned mine up, I crossed my plug wires over top of each other, and it ran rough. As soon as I straightened them out, parallel to each other, it ran great. Of course this is not a scientific test, but it seemed to make a big difference.
Bosch is going downhill rapidly. You should go to the Karlyn site and order the correct wires through them. Through their site they will take you to Bremi (German) caps and rotors; far superior to what Bosch is making these days. Bosch plugs however, are still first-rate.

Kevin
 

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Banned
1993 400E
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7,361 Posts

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Always Remembered RIP
1991 560SEC AMG
Joined
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10,146 Posts
Discussion Starter #6 (Edited)
Progress report 30 Juli 2012

THANKS FOR THE ADVICE!

The Bosch plugs (above) were installed yesterdfay along with the two distributor caps and new plug wires (CORRECTLY and carefully routed) and the tuneup made the car an amazing runner.

That's because the plug wires were original and with Mercedes Benz stars marked on them, and even the plugs were original, it seems!

No WONDER the performance was not sensational; they must still have been the originals at 152,000 miles and 17 years!

I admit I'd assumed there had been tuneups along the way and checked the records I have on the car (bought a year and 3 days ago) back to about 75,000 miles and NO evidence of a tuneup - ever!

Next up:

Installation of the Mercedes Benz OEM new skid plate I had bought earlier this month whioe personally at the Mercedes Benz Neiderlassung "Superstore" dealer - (under the same roof as the mecedes Benz Museum)


























...which now are (I was told),,,, unavailable in USA but purchased there in Stuttgart, and then shipped to me by UPS through St. Louis.

Before the skidplate install, a LOF is in order, Castrol 20/50 and a Fram filter (their best one, Mann not available at the store ..


Appears also the cat is clogged up, it is the original, before replacing it with one, I am going to run a straight pipe a few days from now for a little while to see if it perforjs ofk.

I will leave the resonator as is, and see how it works with the Remus.

Later on reinstall the new cat I need to have on the car.....
 

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Premium Member
'92 300TE 4matic 280,000miles, '92 300TE 4Matic 'Ice Blue Metalic' 101,000miles
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10,468 Posts
I would find a better oil than Castrol 20/50 which was in my car for over a decade. The valve train looked terrible and my rings are somewhat worn. Using a better suited oil over those yrs would probably have netted me better results. I wouldn't put Fram anything on it either.YMMV

Kevin
 

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W124 E420 : W220 S500 : W222 S550
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402 Posts
I am in Europe 2-3 times per year, but not Germany....... I have to put that on my list (note: not "bucket"... I am not thinking about dying.... )

what a wonderful few photos
 
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