Original Plug Leads - does it really matter?

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CraigB
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Original Plug Leads - does it really matter?

Post by CraigB » Tue 23 Oct, 2018 9:56 am

This question comes out of another post and also that i have picked up a 450SEL with a brand new set of "Eagle 7.0mm Eliminator series hi-temp silicone spiral-core cable... Made in Australia"

Normally when i have got a car, especially if not running quite right, I just buy a set of the proper resistance bosch leads and forget about it, combined with non-resistor NGK plugs - because they are the only ones still doing non-resistor plugs.

New member Scottyx has just purchased a new set of these leads, but also the proven and popular 123 distributor. My first thought was 'oh know - wrong leads' but for that ignition system is it? And if OK - should he be using resistor or non-resistor plugs?

Also wondering about these leads on the '79 450 with MB electronic ignition- what sort of problems are likely from running those leads. I'm thinking JG must see this sort of thing all the time on cars - do you religiously replace them all with correct leads?
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Re: Original Plug Leads - does it really matter?

Post by Bartman4800 » Tue 23 Oct, 2018 11:01 am

For the 123 ignition, it does not seem to matter.

They state on their website that leads with carbon core are the way to go. I have copper leads with mine which are fine. These are a bit stiffer, due to the older style (vinyl?) wrap.

As far as spark plugs go, 123 states to use what the manufacturer prescribes. So NGK BP6ES is a good choice in my book.


Bart
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Re: Original Plug Leads - does it really matter?

Post by Ivanerrol » Wed 24 Oct, 2018 11:27 am

The resistance is in the plug ends not the leads. (copper leads)
Silicon leads were introduced to reduce static on car radios.

Use resistive leads, resistive plug ends and resistive plugs and you are far out of Spec for what Benz originally designed.

Anecdotal evidence shows that using extra resistance in the ignition lead sequence works for around 10 - 12 K, then spurious misfires / ignition problems start up.
Personally I stick to the original design. Non resistive leads, resistive plug end and non resistive plug.
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Re: Original Plug Leads - does it really matter?

Post by Bartman4800 » Wed 24 Oct, 2018 12:23 pm

Ivanerrol wrote:
Wed 24 Oct, 2018 11:27 am
The resistance is in the plug ends not the leads. (copper leads)
Silicon leads were introduced to reduce static on car radios.

Use resistive leads, resistive plug ends and resistive plugs and you are far out of Spec for what Benz originally designed.

Anecdotal evidence shows that using extra resistance in the ignition lead sequence works for around 10 - 12 K, then spurious misfires / ignition problems start up.
Personally I stick to the original design. Non resistive leads, resistive plug end and non resistive plug.
Understood.

The issue is here, that we are using a modern 123 ignition distributor (not W123) which has a far higher output than the original points ignition Benz had in the W111/W108 and before that.

I personally do not think it matters that much anymore with the modern setup. I still run copper leads and non resistor NGK plugs because I replaced them before the dizzy and I am a cheapskate. I also like the contemporary look of the original caps.

Bart
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
2011 Kia Sportage "Missus commuter Bus"
2002 Mitsubishi Rosa Bus (converting it to a motor home)

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Re: Original Plug Leads - does it really matter?

Post by CraigB » Wed 24 Oct, 2018 12:57 pm

Thanks - that's a great explanation. I don't know about this eagle brand but I have certainly heard of silicon leads breaking down and needing to be replaced after fairly short intervals (on other cars - when i had a range rover and was chasing problems via forums) and i had what looked like quite new leads and two of them were what was giving me problems. A bit of copper is obviously likely to have a longer service life. And yes as pedantic as it reveals i am I do like the look of those original leads with metal ends..... but how often do i open the bonnet to look! Like i say, most of my cars are already there and maybe for this 450 (with original ignition set up) I will test and reinstall a set of one of my many spare engines!

Just extending that thought though, a 2002 Range rover had what i imagine is and looked like a fairly modern ignition set up, and still the silicon leads were a trap for me when trying to solve a bad idle. So as a general rule I still think I would invest that little bit extra in the copper leads and resistor ends just for lengevity, even if i had the 123 set up, but agree that higher spec shouldn't be a problem with a new set of silicon leads. But good to keep that in mind that after 10 - 12k you find it misbehaving that maybe it could be a lead breaking down. I don't remember what brand were on the Rangie and it is long gone, but maybe they were cheapies and Eagle is good, but I do like the idea of the copper and thanks for clearing that up.
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Re: Original Plug Leads - does it really matter?

Post by John Green » Thu 25 Oct, 2018 1:13 pm

Bartman4800 wrote:
Wed 24 Oct, 2018 12:23 pm
Understood.

The issue is here, that we are using a modern 123 ignition distributor (not W123) which has a far higher output than the original points ignition Benz had in the W111/W108 and before that.
The 123 ignition system has nothing to do with the delivery of the spark? It just times the delivery and sends it to the right spot. The issues with resistance problems are more to do with the electronic systems, especially the later EZL and EZL-AKR systems. When the field in the coil collapses it needs to go somewhere and if it meets a whole bunch of resistance it is possible that it is still discharging when it is trying to fire off the next shot. That's a little of an over simplified explanation, but I am sure you will know what I mean.

So given that you were talking about a 450SEL I would most certainly be using standard leads.
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Re: Original Plug Leads - does it really matter?

Post by CraigB » Thu 25 Oct, 2018 2:20 pm

That's good - what about w108 280s with 123 distributor...... which was the original prompt to ask - Scottyx about to install. No EZL etc.
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Re: Original Plug Leads - does it really matter?

Post by John Green » Thu 25 Oct, 2018 9:32 pm

CraigB wrote:
Thu 25 Oct, 2018 2:20 pm
That's good - what about w108 280s with 123 distributor...... which was the original prompt to ask - Scottyx about to install. No EZL etc.
Ahh yes, just re read the first post... The resistance in the leads is less important on this car. My experience with silicone leads is from 30-35 years ago and they were crap back then, most likely things have improved since then, but i would still stick with good old copper leads.
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Re: Original Plug Leads - does it really matter?

Post by Ivanerrol » Fri 26 Oct, 2018 10:09 am

The real issue with leads is the insulation.

Cheap leads - cheaper insulation. Faster to breakdown due to heat, exposure to fuels and oils etc.

Electrical energy circuits always looks to the path of least resistance. A break in the insulation may cause a short circuit away from the sparkplug. There's a better chance of less short circuiting with copper leads than resistive types.
W211 - E240
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Re: Original Plug Leads - does it really matter?

Post by CraigB » Fri 26 Oct, 2018 11:20 am

That's another good tip that I am reminded of. If you have a misfire, open your bonnet in the dark and also rev the engine - those sorts of shorts will often stand out like dogs appendages.

And just adding to comments here - while googling I came across this page on the Magnecor website. Of course they are trying to sell something and always a good idea to put a vested interest filter on stuff you read, but it does sound particularly well researched and backed up and detailed. I thought it details a bit more the sort of thing JG is referring to and EMI etc.

https://www.magnecor.com/magnecor1/truth.htm
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Re: Original Plug Leads - does it really matter?

Post by Astro-Benz777 » Sat 27 Oct, 2018 4:42 pm

I understand this thread references a 123 Dizzy rather than W123 series however just as an add on "My 2 cents"...
In my (somewhat limited) experience when it comes to Post-1980-ish W123 & W126 series vehicles, it's far better to leave the original blue leads in place (assuming no visible damage) and investigate other causes of any misfire or other spark related issues than replace them with an inferior quality set.... usually, even after 30+ years there's absolutely nothing wrong with the originals.
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Re: Original Plug Leads - does it really matter?

Post by Bartman4800 » Mon 29 Oct, 2018 12:47 pm

I could be colour blind, but all OEM mercedes leads of that era were black...
1963 220 Sb Sedan "Kermit" (Australian Assembly)
1960 220 Sb Sedan "Zum Schlachten" (Early German Assembly, with a torsion bar spring for the bonnet) - Stored in Country WA
1981 Subaru Brumby 1.8 with Weber and 5-speed box "little utie" - Sold to another enthusiast!
2006 Ford Focus "daily driver"
2002 VW Passat V6 30V Station Wagon (SOLD - This car into a money pit)
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Re: Original Plug Leads - does it really matter?

Post by Astro-Benz777 » Mon 29 Oct, 2018 9:25 pm

It might be something particular to the W126 6cyl 280's (being the "Old" M110) actually it might just be particular to M110's generally because I don't think I've ever seen an original one (126, 116 or 123) with anything except old, copper core, blue vinyl (or similar) wrapped leads.
W126's: truly the last real Benz (IMHO) :notworthy:
FORMER FAMILY:
1989 300SE (W126) Midnight Blue, Blue/Grey Interior (Gearhardt)
1982 380SE (W126) Thistle Green, Tan Interior (Sherman)
CURRENT DAILY DRIVE & BELOVED FAMILY MEMBER
1984 280SE (W126) Thistle Green, Tan Interior (Hilda...after my late Gran)

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Re: Original Plug Leads - does it really matter?

Post by TheMadRacoon » Mon 29 Oct, 2018 9:32 pm

My W114 280E had original black leads and an '80 W123 280E I'm sure was the same (it was only 7 y.o. at the time I saw it). I've also never seen blue leads on any Benz from 1970 to 1990.
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Re: Original Plug Leads - does it really matter?

Post by Astro-Benz777 » Mon 29 Oct, 2018 9:42 pm

Well colour me wrong then.
So the leads like in this pic aren't OE then?
280se_engine2.jpg
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W126's: truly the last real Benz (IMHO) :notworthy:
FORMER FAMILY:
1989 300SE (W126) Midnight Blue, Blue/Grey Interior (Gearhardt)
1982 380SE (W126) Thistle Green, Tan Interior (Sherman)
CURRENT DAILY DRIVE & BELOVED FAMILY MEMBER
1984 280SE (W126) Thistle Green, Tan Interior (Hilda...after my late Gran)

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Re: Original Plug Leads - does it really matter?

Post by CraigB » Mon 29 Oct, 2018 9:50 pm

They look the part and mercedes blue like the parts boxes and dealer signs... so why not? Are there any marks on them? The only cars I would be sure had original are both from 1969 and are black, but 1980s were a different time. Curious on JG's comments!
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Re: Original Plug Leads - does it really matter?

Post by Astro-Benz777 » Sat 03 Nov, 2018 4:32 pm

On the Plug Boot end on the metal boot itself, they say the following...
1k 𝛀
K4
BERU
W-GERMANY
0300052103

:dontknow:
W126's: truly the last real Benz (IMHO) :notworthy:
FORMER FAMILY:
1989 300SE (W126) Midnight Blue, Blue/Grey Interior (Gearhardt)
1982 380SE (W126) Thistle Green, Tan Interior (Sherman)
CURRENT DAILY DRIVE & BELOVED FAMILY MEMBER
1984 280SE (W126) Thistle Green, Tan Interior (Hilda...after my late Gran)

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Re: Original Plug Leads - does it really matter?

Post by John Green » Sun 04 Nov, 2018 8:27 am

TheMadRacoon wrote:
Mon 29 Oct, 2018 9:32 pm
My W114 280E had original black leads and an '80 W123 280E I'm sure was the same (it was only 7 y.o. at the time I saw it). I've also never seen blue leads on any Benz from 1970 to 1990.
All M110's had blue ignition leads for some reason....... We were asked for them quite often and never managed to find a source for them.
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Re: Original Plug Leads - does it really matter?

Post by Astro-Benz777 » Wed 07 Nov, 2018 11:22 pm

John Green wrote:
Sun 04 Nov, 2018 8:27 am
TheMadRacoon wrote:
Mon 29 Oct, 2018 9:32 pm
My W114 280E had original black leads and an '80 W123 280E I'm sure was the same (it was only 7 y.o. at the time I saw it). I've also never seen blue leads on any Benz from 1970 to 1990.
All M110's had blue ignition leads for some reason....... We were asked for them quite often and never managed to find a source for them.
Sweet vindication!!
Thanks John!
W126's: truly the last real Benz (IMHO) :notworthy:
FORMER FAMILY:
1989 300SE (W126) Midnight Blue, Blue/Grey Interior (Gearhardt)
1982 380SE (W126) Thistle Green, Tan Interior (Sherman)
CURRENT DAILY DRIVE & BELOVED FAMILY MEMBER
1984 280SE (W126) Thistle Green, Tan Interior (Hilda...after my late Gran)

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Re: Original Plug Leads - does it really matter?

Post by TheMadRacoon » Mon 12 Nov, 2018 8:12 pm

Flamin' wallabies, so mine weren't original!

Well tie me to an ant hill and spread my ears with jam!
Emad,
TheMadRacoon
1975 350SLC Astral Silver (725) / Blue (2012, 284,900 km - present.... a real Benz, getting better and better)
1988 190E Deep Blue (900) / Cream (2006, 190,000 km - 2007, ~ 215,000 km .... FSH and still spent big $$$)
1974 280E Reed Green (860) / Bone (1993, 316,700 km - 2004, ~490,000 km and still A1)

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