Bosch Spark Plug Wires

[rb6667]

Several auto parts stores tell me they have an application for a 68 280SL.  Any of you used the Bosch wires??  Any others that work better??

thanks rb6667

rb6667

[al_lieffring]

If it is the same Bosch wire set that I have, there are 5 straight resistor ends and one that is bent 90deg.

This is the set that in the past was sold for the M130v carbureted engines. The wires work just fine, but if you know that all 6 resistors were originally straight, it might bother you.
It hasn't bothered me enough to buy a second set just for the one resistor.

I have some Beru resistors, but they are yellow cad, the Bosch white cad plated. again an appearance issue, so I am running with the 90deg end on the #1 plug.

Al Lieffring
66 230Sl
Jones'n for a new gas tank

[Shvegel]

I am with you Al I am bugged by the bent resistor end as well. Maybe 5 of us can buy a set!

I have the original wires tucked away for originality. I like the Bosch but that bent one...

[graphic66]

I think those Bosch wires have the incorrect resistance for our ignition systems. From memory,  I think they are 5000 ohm and our cars require 1000 ohm.

[Cees Klumper]

Also it's possible that only that one bent one has a 5K ohm cap, and the others are correct with 1K ohm.

Cees ("Case") Klumper in Amsterdam
'69 white 280 SL automatic

[jameshoward]

Had the same with the leads on my 230SL. The bent plug...

OK - stopped mid flow as Cees beat me to it. The bent one did have the incorrect 5K ohm cap whilst the others are the correct 1k ohm. These simply unscrew - ie there is a screw thread inside the cap. You can buy the 1k ohm beru caps in good shops (at least you can in Europe) so I just bought one for 4 euros, unscrewed the bent one, and put on the straight one. They are all correct for resistance on the right leads. A lot cheaper than a new set.

Agree with graphic66 - you need the minimum resistance. There's lots about this on the site.

[Shvegel]

I wouldn;t get too hung up on the resistance. It is just there for ignition noise resistance. I would however be concerned slightly if the bent one was 5k and the others were 1k. Higher resistance raises the firing voltage which makes a hotter spark which is good as long as it doesn't cause the spark to find a path to ground that doesn't involve the spark plug gap.

The 2 things to avoid like the plague(in my opinion) are carbon core wires and Champion resistor spark plugs. Carbon core wires are notorious for failing and when the resistance is in the wire the longer the wire the higher the resistance. Having 6 different resistances can greatly effect firing voltages between cylinders.

I know our plugs are not resistor plugs but I will say it anyway. Champion resistor plugs must be avoided at all costs. I used to train mechanics for BMW and one of the things I liked to do was buy a set of Champion resistor plugs and hae a student bring in a used set.
The new set would always be close to 5k resistance and the used set would always vary between 5 and as high as 27k ohms.

[hauser]

I found this while looking for sparkplugs.

http://www.stopshopanddrive.com/item.wws?sku=BSH008862&mfr=Bosch

1969 280sl 5 spd
Gainesville, Fl.

[rb6667]

Ok, Let me see if I understand this, the bent one has higher resistance, but the straight ones are ok to use??  I guess one solution would be to purchase 2 sets of wires, and not use the bent one.  Anyone need some extra wires??  LOL.

rb6667

rb6667

[ja17]

The early W113 cars without the factory electronic ignition used the non-shielded 1,000 ohms spark plug ends #000 159 3210 and are often refered to as "far range".  


The later W113 ignitions with the metal shielded spark plug ends "close range" #000 156 3010, #000 156 3210 were 5,000 ohms. I believe these were used on the later W113 cars with the factory electronic ignitions?

All the factroy wire sets used solid stranded copper wire which was tin coated  #110 159 1818 (by the meter). This was very good stuff and would not fail unless the insulation is shot. The wires misfire when the resistor ends go bad causing too much resistance, then the spark cannot get through or jumps and shorts causing a miss. Many original cars are still using the good factory original wire set after 40 years!  The wire resistance can be checked and the bad spark plug wire ends can be replaced (they screw off if the set is original). You use to be able to order new original wire by the meter (above) and "build a new set using your good ends and boots. Do not throw your originals away. Chances are you will never get set built and fitted as well.

Most of these cars have had the original ignition combinations scrambled up. If you have a standard ignition and your car is eating up points you may have a bad combination of coil and/or ballast resistor.



Joe Alexander
Blacklick, Ohio

[Benz Dr.]

The 90 degree end is for cars with carbs. You need the 90 degree end to fit behind the distributor on those cars.
I've seen some of these Bosch wire sets and I'm not impressed. Carbon core coil wires, resistor ends on everything, 90 degree plug wire ends and 5,000 ohm resistors - in short, they're crap.
 It will make a difference if you have too many resistors in the circuit. Each one is at least 1,000 ohms with the rotor being about 5,000 ohms. The worst case would be carbon wires, resistor ends at 5,000 ohms and resistor plugs. You'd be lucky if it would even start. You'd would be quiet though....

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[mdsalemi]

Just so everyone is clear here...

1)  This 90 degree end with the 5K resistance, etc. is in a pre-assembled Bosch aftermarket kit that they sell EVERYWHERE.  It's only appeal is that it is cheap and available.

2)  There are so many parts suppliers out there and many of them sell the nearly-original Beru metal ends and or the nearly equivalent Bosch metal ends with the proper 1K resistance.  You simply have to build your own.

3)  There are many specific suppliers out there who will assemble the correct wire set with the correct parts.  I spent about 15 minutes in a google search a few years ago before I found a supplier.  His only problem was the wires were too long, but all the parts were right.  (Dan Caron shortened them all up for me!)

The only issue is that many of us balk when it comes to price.  The proper plug ends run $12 and more each; then you need the distributor ends, too, and the wire.  It isn't unusual then for a set to exceed $100; do the math.

When a pre-boxed Bosch set costs $38.50 (albeit with the wrong parts)at Jimbo's Foreign Auto Supply, it's hard to make the walk to $100+

If you do not show your car in a Concours, your opportunities expand greatly as you don't need Bosch or Beru parts--just solid wire and resistor ends.

Michael Salemi
1969 280SL
Signal Red 568G w/Black Leather (Restored)
President, International Stars Section
Mercedes-Benz Club of America

[rb6667]

Very good information guys, that's what I was looking for.  I am a car guy, have 3 60's American Muscle Cars, so I'm used to making things work.  I'll see if I can find the correct spark plug ends, and make my own, using the correct wires, and ends.  I know those pre-assembled kits do not fit too well.  You always have to shorten some of them.  

Thanks again for the great response.

rb6667





rb6667

[Benz Dr.]

The wire sets I sell are correct for 190SL's, pretty close for 230SL and not that close ( as far as lenght goes ) for 280SL but all are correct with the right distributor cap ends and proper resistance spark plug ends.
 All you need to do is cut the wire to the right lenght. Something you would be doing anyway if you bought a box of parts to make your own. I believe the proper pre made sets are the best choice and are resonably priced.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[rb6667]

Update!  With all this talk about Beru wires, I checked mine, and they are Beru.  Wires are blue in color.  Plug connectors have a gold Cad plating, with the wording Beru, West Germany.

 Reading some of your posts, it appears that these spark plug connectors can be re-used.  Is this correctZ??  How do you remove the wire from the spark plug connector?  I know I will have to get new distributor ends.

Thanks very much, rb6667



rb6667

[psmith]

Just for perspective or grins, I was quoted $500 for factory plug wires for my 98 Audi A6  [:0]

Pete S.

[jameshoward]

rb6667,

I managed to reuse my ends. The ones I had were connected to the wires by a small screw thread inside the cap. You simply unscrew the cap off the wire and then screw it into the new wire. Simple as that. Just read some of the posts here about which wire to get, esp those by Dr Benz and ja17 - lots of reference to carbon wire, what NOT to use, resistance (as little as poss) etc.

JH

[Benz Dr.]

The set I checked on the gold car I have in right now had a carbon core coil wire - the absolute worst place you could have a carbon core wire in the system. It chokes the spark down to nothing. The car would still run but the plugs were dark and the oil smelled like gas because it was so dilluted from improper cumbustion.
I removed the wire and used the caps and metal ends - they were new after all. I took out my ohm meter to show the customer and set it to 20K on the replacement wire which showed next to zero resistance. I moved it over to the carbon core unit and I couldn't even get a reading.

Imagine a lawn sprayer with a hose running over to your house. You have about 60 PSI coming out at the tap and the sprinkler runs great with a fountain 20 feet on each side.
Imagine what will happen if you step on the hose or put a kink in it. It will dribble out the other end. You still have 60 PSI pushing through the small crack but very little coming out.
Carbon core wires do the same thing. They cut the spark back a lot. If you have a modern 60,000 volt electronic system it probably won't matter but our cars run on 15,000 volts or less in some cases so every bit counts.

Dan Caron's
 SL Barn
benzbarn@ebtech.net
 slbarn.mbz.org
  1 877 661 6061

[rb6667]

I searched the archives and found that the original wires were black in color for the 68 280SL??  The ones I have are Blue...but they are Beru wires with the gold spark plug ends.

I do not see a screw holding those gold caps on.  Can these caps be re-used?  Benz DR.  Comments?
 

Thanks rb6667

rb6667

[al_lieffring]

quote:Originally posted by rb6667

I searched the archives and found that the original wires were black in color for the 68 280SL??  The ones I have are Blue...but they are Beru wires with the gold spark plug ends.

I do not see a screw holding those gold caps on.  Can these caps be re-used?  Benz DR.  Comments?
 

Thanks rb6667

rb6667

The 280 twin cam motors came with blue wires that had thicker insulation and 5k ohm resistors. The resistors usualy are marked with the resistance stamped on the metal shield.

The screw is inside, the risistor is twisted onto the end of the cable and the screw drives itself into the conductor in the middle.

Al Lieffring
66 230Sl
Jones'n for a new gas tank

[rb6667]

Al, you are correct.  I checked the spark plug ends and they indeed are 5K Ohms. These wires are way too long also, the previous owner used wire ties to bundle them up which caused a miss.  I took the wires ties off, and no more miss.  Obviously crossfire at work here.

I'll be on the hunt for the correct 1K Ohm wires, and connectors.

Thanks again for all the great responses.

rb6667



rb6667

[al_lieffring]

The NAPA web site shows in thier catalog metalic spark plug cable available in 100 foot rolls.

part #734803
The original cables were 7mm in diameter and had black insulation.

Napa also lists blue 7mm metalic cable with high temp silicon insulation.



Al Lieffring
66 230Sl
Jones'n for a new gas tank

[rb6667]

Thanks for the leg work Al.  I'll see if there is a way this can be purchased by the foot as needed.  100ft would handle a lot of cars.  Group purchase anyone??

rb6667

rb6667

[hauser]

I found bulk wire from Beru.  I don't know if it's the correct wire or not.

http://www.kingsborne.com/beruwire.htm

1969 280sl 5 spd
Gainesville, Fl.

[ja17]

Hello Hauser,

The Beru is "copper stranded" so it looks like the stuff! The Napa "metalic" cable of Al's may be the right stuff also.

Here are some original ends;
Download Attachment: ignition.JPG
33.98 KB


Joe Alexander
Blacklick, Ohio

[al_lieffring]

I don't doubt that Joe or Dan have seen these sets made with carbon wires, but the set I bought from Bud's Benz last summer have "Copper Core" wires, I even pulled back the boot on the distributor end to look at the cable, and there was indeed metalic wire, the copper seems to be nickel plated for corrosion resistance.

Now If I could find 4 other people with these same wires that would want to split the cost of  buying another set to replace the 90deg resistor on the #1 cable

Al Lieffring
66 230Sl
Jones'n for a new gas tank

[jameshoward]

Al,

Are you really thinking about buying a new set just to get the straight connector for cyl no 1? You should be able to pick up a beru 1k ohm plug socket at your local dealer. As you know, they just unscrew the 90 degree socket thing and screw in the new plug socket and away you go. If you need one of these and really can't get one, I think I could get one here and send it to you. They don't cost much. Let me know.

If I've got this all muddled up and have missed your point, ignore me.

Incidentally, SLS now only sell the wires set with the 5k ohm ends. They cost 90 euros at set, which is about that in $ or about GBP60. They insist that 5k ohms is correct for the 113.

JH

[Raymond]

"They insist that 5k ohms is correct for the 113"  They would be wrong.
At least partly. 5k-ohms may be correct for '71s but there is plenty of evidence on this site to prove that no resistance would be best for the earlier cars.  For the '68 you want the low resistance plastic connectors.  You want copper core for low resistance.  You want straight connectors with no resistance added, you want plugs that aren't resistors.  In short you want as much wallop from the coil as you can get.

By the way, improperly posting photos can cause the text window on this forum to stretch out.

Ray
'68 280SL 4-spd Coupe

[ja17]

Hello,

Early 280SLs and earlier W113 cars without the factory transistorized ignition used the 1,000 ohm plastic spark plug connectors. Later 280 SLs with the factory transistorized ignition had a much more intense spark so they used the 5,000 ohm metal shielded spark plug connectors.

If you have upgraded your ignition system with a hotter coil or modern ignition, the 5,000 ohm ends work just fine on even the earlier cars. Using the 5,000 ohm resistors on the original early non-transistorized ignitions is a strain on the system.

Joe Alexander
Blacklick, Ohio

[Mike Hughes]

Would the "strain on the system" when using 5000 ohm metal resistors on an otherwise stock early system manifest itself in rapidly pitted points, etc.?

quote:Originally posted by ja17

Early 280SLs and earlier W113 cars without the factory transistorized ignition used the 1,000 ohm plastic spark plug connectors. Later 280 SLs with the factory transistorized ignition had a much more intense spark so they used the 5,000 ohm metal shielded spark plug connectors.

If you have upgraded your ignition system with a hotter coil or modern ignition, the 5,000 ohm ends work just fine on even the earlier cars. Using the 5,000 ohm resistors on the original early non-transistorized ignitions is a strain on the system.

Joe Alexander
Blacklick, Ohio

- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havanna Brown (408)
  Light Beige (181)
  Cream M-B Tex (121)

[ja17]

Hello Mike,

The points are actually on a different low voltage "primary" circuit. The points should not be effected. The high voltage to the spark plugs on the non-transistorised cars comes from the high voltage terminal (center) of the coil. The high voltage current flows through the coil wire and any rssistor ends on this wire, through the distributor cap, through the rotor and it's internal resistor, back through the distributor cap, through the spark plug wire ends at the distributor with it's resistor, through the spark plug wire, through the spark plug connector and it's resistor, into the spark plug (hopefully non-resistor) and finally the spark!  
Any weak link along the way adds resistance. With the metal shielded spark plug wire ends you start off with 5,000 ohms resistance, you have a resistance built in the rotor (5,000 ohms), and you also have resistance built in some of the wire ends at the distributor in most cases (1,000 ohms). Now if you have the wrong spark plug connectors, or carbon spark plug wire, resistor spark plugs (5,000 ohms),or any other weak failing resistor in the system you have too much resistance and the spark intesity will suffer or fail completely.
Say you have the original early (non-transistorized) ignition system. You should start to be concerned when the total resistance in a single spark plug circuit exceeds 13,000 ohms total from the coil through the spark plug.  So we can compute; coil wire ends (two) 2,000 ohms, rotor 5,000 ohms, distributor end of plug wire 1,000 ohms, and the wrong spark plug connector 5,000 ohms, then you add some resitor spark plugs at another 5,000 ohms!!  You now have a total 18,000 ohms with all new parts, and are over specs to start with! The resistance in many of the parts will increase with age also. The electricity will follow the path of least resistance. So when the resistance becomes to high the spark will simply jump out of the circuit (arcing) or not make it at all causing a miss.


Joe Alexander
Blacklick, Ohio

[Mike Hughes]

So would the extra resistance introduced when using the 5000 ohm metal connectors instead of the 1000 ohm plastic ones cause a weak enough spark to make the plugs foul when they otherwise would not?

- Mike Hughes  -ô¿ô-
  1966 230SL Auto P/S
  Havanna Brown (408)
  Light Beige (181)
  Cream M-B Tex (121)

[ja17]

Hello Mike,

If your coil or ignition system has been upgraded with a "hotter" set up the 5,000 ohm ends are no problem.

Most likely the 5,000 ohm  ends will work fine on an original early set-up also. However, you are starting out with a disadvantage which may bring on problems sooner.
Complete failure may not happen until much higher resistance, but issues like hard starting, (especially in damp weather), spark plug fouling, and spark arcing through wire insulation may occur sooner.

If you have carbon spark plug wires, instead of solid copper,  you are adding much more resistance also. As mentioned, resistor spark plugs will add another 5,000 ohms resistance.

Each spark plug wire should be checked with an ohm meter during a tune-up or as needed. This will tell you the condition of the spark plug wires and the resistor ends.

Joe Alexander
Blacklick, Ohio

[J. Huber]

Resurrecting this one... and it all makes sense (sort of) but I wanted to be sure. For a lot of years I have been using "Bosch 7mm Opti-layer copper core Ultra premium " wires. The ends are 1K ohm except the the first one that is the 90 degree 5K.

It is my understanding that I can just change out the 5K (0 356 351 027) for a straight 1K (0 356 301 022). And that the ends screw on. Does this sound right? Do you suppose this will affect the running of the car in anyway?

[bosch red coil, 1.8 ballast resistor, NGK BP5ES plugs]

thanks as always

[jameshoward]

James,

Yes, you can. It's what I did after reading this post.

I went to my auto parts supplier and purchased a new end made by Beru (subsequently edited to provide the correct manufacturer's name after Graphic's post; they are very widely available in Europe; not sure about the US)  that just screwed onto the wire. I checked the readings thereafter and it was exactly the same as the others. Took all of 5 minutes.

James

[J. Huber]

Thanks James, I plan to try the new straight connector soon. Let's see...5 minutes for you = hmm. Ok I'll plan for an hour...

[graphic66]

Anybody ever find a source for Beru wire and ends.

[66andBlue]

Try Kingsborne - very knowledgeable including older parts.
http://www.kingsborne.com/connectors.htm

[waqas]

Anybody ever find a source for Beru wire and ends.

Have you checked with Dan Caron (Dr Benz)?  At some point, he had pre-made sets available in both Bosch and Beru.

[Benz Dr.]

Thanks Wagas, I still can get those wire sets.

This is what you should use based on my recommendations:

26 KV red coil on early systems
1.8 ohm ballast resistor
coil wire without any resistors
new rotor if it has more than 5 K ohms resistance
spark plug wire with no resistors at the distributor cap and 1 K ohms at the spark plug
Bosch W9DCo or similar plug. W7DC is too cold for most engines even though that's the rated plug.

On later ( original ) CD ignition systems I would use the same parts but would leave the coil and any ballast resistors in stock trim. Plug wires don't need the resistor ends on them and you defiantly don't want resistors on the coil wire. I like the same 1 K ohm ends at the plug wires which should have metal ends to be correct. The earlier bakelight ends will also work.

Some of the replacement electronic system instructions indicate that you can remove the ballast resistor. Read the instructions carefully or contact the supplier/manufacturer before you do. The ballast resistor protects the coil from over heating when you leave the key on and the car isn't running. The coil and ballast resistor can and will get very hot even when the engine is running.

[graphic66]

 Dan, How long can you leave they key on without the engine running and not damage the coil or points on your setup. I am very hesitant to play my radio without the car running as my 230SL doesn't have an accessory position. The old radios sound very good at outdoor picnics and such but I am afraid to play it for fear of damaging my coil and points..

[zoegrlh]

A year ago I bought two sets of the Bosch wires in order to have all stright ends and proper restistance for all 6 wires.  They work well, and look good, and have Bosch stamped along the wire for that dressed-up look.
Bob