upgrade spark plug wires - PeachParts Mercedes-Benz Forum

CamelotShadow · #1 10-23-2007, 05:26 PM

Quote:

Originally Posted by Graham

I ordered a complete (supposedly OE) Bosch system from ******** for my '72 350SL.

The distr cap and rotor are OE type.

The wires are Bosch Premium (Opt-Layer Mag) and plugs are Bosch resistor type. The wires do not have resistors built in and are not copper. Box is contradictory in that it says wires are stainless steel spiral wound for American and Asian cars only but also says they are for Mercedes V-8 engines!

Original '72 vintage wires had resistors built in to end fittings - 6kohms at one end and 1.6 kohms at other and presumably copper wire between. Plugs were non-resistor type.

Total resistance of original system was about 8 kohms. New wires are 1.6 kohms and with plugs may be about same as originals. I wonder if it makes any difference what wires we use, so long as overall resistance of circuit from coil to plug tip stays approximately the same??

I went ahead and installed the new parts. All I can say, is that the car is running well and that it does not miss from idle up to max revs. No interference on radio. One experienced MB technician says my set up is fine and he has been working on MBs all his life.

I still have original blue coil. I have been thinking about switching to Pertronix point-less ignition (Ignitor). They sell a coil that goes with their system for about $40.00. have not determined yet if this would be suitable for our car. But, you should be able to get an OE equivalent coil from any of the on-line vendors.

I got the bosch dis cap & rotor too
as well as the Same Bosch Prem opti wires
Now I don't know what to do as
I paired it with non resistor NGK plugs

The cap & rotor r in but still have to install plugs & wires

I'm not so worried about the radio
just want to do what best for running the car...

So what are they doing
changing the wires to deal with the unavailability of non resistor plugs?
What about if we have the spec non resistor plugs
then what kind of wires do we get???

Jim B. · #2 10-23-2007, 06:36 PM

Beru plug wires are the best for the W126 vehicles.

CamelotShadow · #3 10-23-2007, 06:43 PM

Quote:

Originally Posted by Jim B.

Beru plug wires are the best for the W126 vehicles.

Was trying to save where I could
It's hard when u live on a very limited income
& drive a benz...

Was hoping Bosch would make a decent quality wire
& that it would pair up with the bosch rotor & distr cap...

Who knows
but I have them & hopefully new bosch will be better than the old ones on there...

Have to talk to Enrique
I might havew to see the Bosch or take a stock loss & return them to Rusty.

I'd think about exchanging them
buy they just take so long to get here
& I;d like to have this done by xmas
I;m sure you can understand that...

mbzr4ever · #4 10-24-2007, 12:51 AM

Quote:

Originally Posted by CamelotShadow

Was trying to save where I could
It's hard when u live on a very limited income
& drive a benz...

This is true, but just think about how much you are saving by doing the work yourself.

Just today, I changed my wires to the Beru for my 300e (w124). They say silicone on them and they sure look nice. Ok, so it took me 2 hours to change the wires, rotor and cap, but I took my time - you know how females are....

My mechanic would have charged me $95 per hour, so I know I saved at least that much.

CamelotShadow · #5 10-24-2007, 01:24 AM

Quote:

Originally Posted by mbzr4ever

This is true, but just think about how much you are saving by doing the work yourself.

Just today, I changed my wires to the Beru for my 300e (w124). They say silicone on them and they sure look nice. Ok, so it took me 2 hours to change the wires, rotor and cap, but I took my time - you know how females are....

My mechanic would have charged me $95 per hour, so I know I saved at least that much.

Ohhh I don't mind doing work or saving money
but I have to admit
sometimes you have to get expert help

I don't even know if the wirs I got are really right for my car
Its a Euro & parts can be extremely confusing

I don't mind paying to get things done right
I'm no expert but I try my best
Did Ok w rotor & cap
Saved $
but I;m not in the mood to have anything else break
got to get a therm vac valve replaced
because I broke it
So did I save $$$
maybe not
but I mat still have gotten more for my $

Graham · #6 10-24-2007, 07:53 PM

Quote:

Originally Posted by CamelotShadow

I got the bosch dis cap & rotor too
as well as the Same Bosch Prem opti wires
Now I don't know what to do as
I paired it with non resistor NGK plugs

The cap & rotor r in but still have to install plugs & wires

I'm not so worried about the radio
just want to do what best for running the car...

So what are they doing
changing the wires to deal with the unavailability of non resistor plugs?
What about if we have the spec non resistor plugs
then what kind of wires do we get???

I asked the vendor and they asked Bosch. The story I got, was that the old copper wires with resistors are old technology and no longer made (at least by Bosch). They also said that Bosch no longer makes non-resistor plugs. But, the vendor did say he was just repeating what a Bosch rep had told him. He asked me to let him know if I unearthed more info, because he keeps getting this type of question!

Regarding damaging the ECU and coil. I don't understand why that would happen, if the circuit from the coil to the distributor and from the distributor to the plug tip has the same resistance as the original design.

I have asked a few experienced MB mechanics about this and they feel that my set up (New low resistance wires with resistor plugs) is fine. The car is certainly running well. In your case, you may want to use resistor plugs with the new wires (But what do I know??).

I have not had much luck getting anyone on the various forums much interested in this subject. Mostly just get old axioms like "don't use resistor plugs" and so on.

But it seems things have changed and we need more info to move forward.

I wrote to Bosch Canada, but no response. I may try calling Bosch USA, but you might want to too:

Bosch Customer Service:
888-715-3616
(Monday thru Friday 8:00 am to 5:00 pm CST; for U.S.)

CamelotShadow · #7 10-24-2007, 09:53 PM

NGK bp5es plugs are in w prem bosch wires
dis cap & rotor now

Runs smooth
Not sure if it runs any smoother though
as it ran very smooth before.

Guess its working
I just want to have things just right.

They make advances in wire technology
Wires just transmit the energy & less resistance could be better
just as long as the right amount gets to where its supposed to go.

I got a slightly hotter plug in there
but with a hi mileage engine
coupled with non autobon speeds the plug might be just right

Graham · #8 10-25-2007, 11:58 AM

I called Bosch Customer Service (888-715-3616). They called me back.

I was told that the #09027 are the correct Bosch wires for the 4.5SL. He could not explain why box says for Mercedes V-8 AND also for American & Asian cars only, but thought it was because it is a generic box.

He said we should be using resistor plugs and that WR7DC+ were correct for the car. He said the lower wire resistance should improve things. He did not know what the resistance of the plugs were.

The rep was not too convincing, but I guess car runs fine, so why argue with success?

CamelotShadow · #9 10-25-2007, 02:29 PM

Always resistance in a wire
nature of a wire
but resistance is not good
The easier the signal flows the better.
but you would want to end up hitting the combustion within the spec perameters

don't know the specifics
but I got the prem bosch wires don't even know model
just the ones Rusty sold for the 83 SEC

So how does it work?
Coil is the powerhouse?
transfers current to distrib cap
then travels to plugs to ignite fuel air to make combustion?

with less resistance in wires there should be more current hitting the plug faster

dont necessarliy think a hotter plug carries more energy
its just has a thinner ceramic coating which allows the plug to stay hotter
burnning uo more carbon under low soeed city type driving whuch we have alot of

I would suspect but it would worry me
that a lower resistance wire coupled w the no resistor plugs might increase the applied voltage available...but I have read only the amount needed to jump the gap will be used which is in the 10,000 to 30,000 range volts

Thing to look for is the dis cap
if there is a problem there
have to trace it to either a wire or plug
installing a new cap will not correct the condition causing the arcing...

Anyone help clear up my frizzy thoughts

I got the plugs & wires in now
so hoping all is fine but I wouldn't want to damage or prematurely wear anything out...