Author Topic: Spark plug connectors (Read 16158 times)

69280sl · « **on:** May 15, 2009, 14:50:12 »

I was trying to figure out if my 1968, 280sl should have bakelite or metal sleeve spark plug connectors. Tom Colitt provided a good answer which I post here to possibly inform others as well.

" Gus, it was not a matter of early or late. The metal connectors were used as an interference suppression when a radio was installed, otherwise the bakelite were used. Both Bosch and Beru could be found, the Bosch were white cad, the Beru Yellow and also depended on factory installed/ prepped or dealer retrofitted."

Good Luck, Tom

Naj ✝︎ · « **Reply #1 on:** May 15, 2009, 18:42:01 »

Did he say if they should be 1k or 5k with radio?

Maybe 5k....

naj

69280sl · « **Reply #2 on:** May 15, 2009, 21:04:11 »

Good question Naj. He didn't say, I posted his response in total.

Benz Dr. · « **Reply #3 on:** May 16, 2009, 05:30:52 »

Use 1K and you'll be OK. The plug ends for metal or bakelite are really all the same. The difference is some have the metal shields and some don't. The function and basic parts are the same.

However, I've seen Bosch sets with the number one spark plug terminal at 90 degrees. This set is for cars with carbs but will work on our cars. The spark plug terminal may bother you but the really big thing that should bother you is that ALL of these incorrect sets have coil wires that are carbon core. Why Bosch did this is a complete mystery to me but they did.

Go and check if you have this set up. Pull the coil wire and you will see a black string in the centre of the wire or where a metal wire should be. I take the boot and metal ends off and get a regular metal coil wire ( spark plug wire ) and reuse the boots with ends. I have a special tool which makes that job pretty easy to do. Make sure you leave about 10 - 15 mm of wire sticking out the end of the wire and then fold it under the metal end before crimping so that the wire and end are touching each other for proper contact.

A proper coil wire will make your engine come to life, start better and idle smoothly.

69280sl · « **Reply #4 on:** May 29, 2009, 18:26:56 »

To finish this off... MB Classic Center advises that all W113 cars should have spark plug connectors with !K ohm resistance. No radio = bakelite. Radio fitted = metal sleeved (suppressors).
The 5K ends are for "larger engines" but the tech was not specific as to which engines.
Gus

Benz Dr. · « **Reply #5 on:** May 30, 2009, 03:22:32 »

That's because he's wrong and couldn't come up with any examples. It's 1K and THAT'S IT.

wwheeler · « **Reply #6 on:** June 01, 2009, 19:53:36 »

If you don't listen to the radio but rather listen to the symphony coming out the exhaust, can you eliminate the 1K connectors at the plugs to increase the spark? If so, what other things would be affected?

Benz Dr. · « **Reply #7 on:** June 02, 2009, 02:33:23 »

Fort the most part - nothing. The static affects certain things more than others. AM radio is affected a lot more than FM but who listens to AM these days? It was all you could get in a car back in the 60's.

I go to sprint car racing. They use magnito's instead of points and coil or even electronic. The magnito produces its own voltage - the faster you spin it the more it makes. Top fuel dragsters also use the same type of set up because it requires no battery or starter so it saves weight.
Most of the PA systems at typical race tracks are affected by the unshielded mags on these cars and you will hear the PA break up as they pass. Who cares, they sound better than the PA which you can't hear anway.

Allenh · « **Reply #8 on:** August 08, 2009, 20:25:02 »

My '64 has metal shields. the #1 of the set is at 90 degrees, a carb set, but the resistance is 5K. all of the srtaight ones are 1K. Love to be able to find a loose straight one somewhere. They just screw off the cable. I bought some high quality copper cored cable and made a new set for my car. Fit and fuction are excellent, custom fit, but that odd 5K end bothers me.

Allen

J. Huber · « **Reply #9 on:** August 09, 2009, 02:39:40 »

Hey Allen. Try Dave Gallon. He sold me a straight 1K to replace my 90 5K. Very reasonable -- fast delivery.

Dave Gallon · « **Reply #10 on:** August 09, 2009, 20:16:23 »

The suppressed spark plug connectors for 280SL were 5K Ohm! ~~I have attached a scan of the page from the Service Manual (OK, the BBB) which clearly shows that the 280SL/8 had six "5 KOhm straight design" spark plug connectors.~~ In addition, I have an NOS set and many used connectors all of the correct Bosch or Beru part number which are marked 5K Ohm. Now, is that important today for a driver? Probably no. Nevertheless, I stick to these specifications and, in my view, they must be correct for a top show car. Tom Colitt and I have extensively researched this topic and have invested quite a bit of time on the restoration of these parts. Perhaps someday we will have some stock for sale.

Thank you, James, for your reference!

James has a later set of spark plug connectors with five straight and one right-angle. (As the page from the Service Manuals shows, this set of for the 280S/8). Happily, I was able to exactly match his straight connectors with a current production part. I would need the Bosch part number from the straight connectors to insure I could do this on an arbitrary ignition wire set.

Please see my later post for correct scans!

69280sl · « **Reply #11 on:** August 10, 2009, 03:46:31 »

Dave: I dont understand the first chart. It shows 6 straight connectors AND 1 angled???

Gus

Dave Gallon · « **Reply #12 on:** August 10, 2009, 20:32:22 »

Sorry for the confusion!! The scans I originally posted are from an earlier edition of the Service Manual and have an error relating to the "angular connector". A later revision of this page was corrected. I have attached scans of the corrected page for your reference. The conclusion, however, is still the same. A 280SL with radio interference suppression has 5K Ohm spark plug connectors.

mdsalemi · « **Reply #13 on:** August 11, 2009, 12:17:55 »

Dave,

Does Beru NOT supply 5K straight connectors? I know the "proper" metal connectors, straight, are availalble

http://www.beru.com/english/produkte/stecker.php
http://www.racepages.com/products/index.php?N=6076+1073+1668+4294962861

...as examples. But, I note they do not list the resistance.

66andBlue · « **Reply #14 on:** August 11, 2009, 16:34:04 »

Beru does supply 5 kOhm straight (and other connectors) and the resistance values are also published.
See: http://www.kingsborne.com/connectors.htm

Dave Gallon · « **Reply #15 on:** August 11, 2009, 18:24:11 »

Michael,

I am not quite sure what to make of your post. As to the links, the first points to connectors that are definitely not original. The second link points to a web page that contains inaccurate information (I have been there before!). If one looks at the model / year ranges advertised for the spark plug connector, it is obvious that they have chosen one connector and are attempting to make it fit where several different connectors were originally used. In fact, the connector they are selling simply will not connect to a 280SL original ignition wire! Your 5K assertion is simply wrong. Please look at the attached scan from a Beru catalog. Beru part number BA 4/14/5 (0 300 071 002) is the original Beru connector for a 280SL (and many other Mercedes from this period). Its characteristics are 5K Ohm resistance, 87mm long, uses a "wood screw" to connect to the ignition wire, and has an M4 thread to connect to the spark plug. I do truly wish this part was available but, unless there has been a change in the last few months, it is not available. Now, note Beru DBAL 4/14/5 P (0 300 072 003). Its characteristics are 5K Ohm resistance, 97mm long, uses an M5 screw to connect to the ignition wire, and an M4 thread to connect to the spark plug. If you look at the "Race Pages" illustration, it is obvious that this is the part they are selling and, yes, it is available. Besides the fact that the two connectors are obviously different appearing, the M5 thread interface to the ignition wire is the big problem: the ignition wire must have a female M5 thread connector crimped on its end to mate with this connector. A 280SL simply has a cut off piece of wire to receive a "wood screw". The Beru DBAL 4/14/5 P is for use on the 3.5 and 4.5 liter V8s beginning in 1969 (we have a 280SE 3.5 coupe, we are the original owners of a 280SEL 4.5, and a 300SEL 4.5 - I know the spark plug connector used on these cars. Finally, in case you are thinking, "Why not adapt the DBAL 4/14/5 P for use with the 280SL?", there is a problem. The female M5 thread connector is not available separately, I have searched everyplace I know. Oh, and the V8 ignition wires are very expensive. I hope this helps to clarify the issue.

mdsalemi · « **Reply #16 on:** August 11, 2009, 21:29:17 »

Dave,

It was a question, do they supply the 5K or not? You indicate not. Asked and answered??

Maybe my 1K's are why I get some static...

If NLA we have to go with a close equivalent however. What would that be?

Benz Dr. · « **Reply #17 on:** August 12, 2009, 03:18:31 »

I've seen original spark plug wires on 280SL's and they were 1K ends. 5K ends may have been used on cars with radios but I wouldn't use them andf crrtainly wouldn't recomend them. The problem with books is people read them, see what appears to relate to their questions, and then it's gospel.

The standard 13 KV coil isn't that strong and you want all the spark you can get at the plugs. Aside from high end car shows stick with what works best which is 1K spark plug ends for every day driving. How long have I been posting about ignition systems around here and still the same questions come up as though it's something new?

Complete new system consists of:
26 KV red coil
1.8 ohm ballast resitor
Beru solid core wires with straight ends
( Some sets with 90 degree number one plug have carbon core coil wire. Save the ends but get rid of the coil wire and get a steel core wire. I prefer coil wires and distributor cap terminals without resistors which only cut the spark back. )
W9DC (o ) spark plugs or NGK BPES5 ( I'm not that familiar with NGK plugs so I might not have that number just right but you want a hot plug )

The later plug wires and spark plug ends used on 380SL's and the like really have no bearing on this discussion other than for reference.

Things are very different today than when these cars were first built. Different fuels, different oils, different tires, different a lot of things so you have to adapt to what works.

Dave Gallon · « **Reply #18 on:** August 12, 2009, 06:12:27 »

For those of you reading this thread who have any interest in historical accuracy vs. hearsay, I thought I would report that it is a fact that my 1968 US Version 280SL was built at the factory with radio interference suppression and was delivered originally with metal shielded 5 KOhm spark plug connectors. (It still has them!) Further, I have an NOS Bosch radio interference suppression kit dated January, 1968 which contains 5 KOhm spark plug connectors. I have attached scans of the instruction sheet; look part way down the second page for the spark plug connectors. By the way, the Bosch part number in the kit exactly matches the part specified in the Mercedes Service Manual. I always find facts interesting and refreshing, don't you?

As I have already said, this information is probably not important for those endeavoring to have a daily driver. It is a question of accuracy and a matter for the concours judge. (Or, for those such as me who are mildly insane and crave originality.)

waqas · « **Reply #19 on:** August 12, 2009, 07:25:45 »

Sounds like we're all violently agreeing.

It seems the consensus is this:

1k ends on cars without radios (maximum spark)
5k ends on cars with radios and hence built-in radio suppression (less than maximum spark)

This makes perfect sense. As discussed many times before, the max ignition path resistance is something like 15k or 16k. Mercedes expected all cars to be maintained perfectly to all specified tolerances. If there was no sacrifice, MB would have recommended using 5k ends across the board, radio or no radio. After decades of use, many of us may not know how much margin our ignition systems have left, so why not try to maintain the maximum margin possible?

So it is indeed useful to know the correct ends to use on a car fitted with radio interference suppression built in. However, I can vouch for Dan's recommendation to use the ends which maximize the spark. Since upgrading to 1k ends, my car hasn't run better.

Radio static be damned, I prefer the sweet purr of my engine!

mdsalemi · « **Reply #20 on:** August 12, 2009, 12:33:37 »

Dan,

The same questions come up because new people show up; or questions arise because what once were not problems or issues for long time members or lurkers, become questions or issues, and it bubbles to the surface again.

BTW I have a 40KV coil from Pertronix.
The ballast resistor is for show only--not used.
I have 1K ends, with a little static in the radio. But top down you can't hear a darn thing anyway.
They may not be 100% original, but the ends I have are pure Beru. They look as close to original as you can buy today.
I have the original set of wires, also 1K Beru. The only difference in appearance is slight shape where the wire screws in at the top.
May not be 100% perfect, but is better than what you even get at a dealer these days, and certainly better than plastic/bakelite ends from Bosch.

Maybe with this 40KV coil I can find some close-looking 5K ends and have a clear radio...

Benz Dr. · « **Reply #21 on:** August 12, 2009, 15:00:43 »

Anyone can say anything here and be an expert if no one knows the difference . In that regard, a lot becomes hearsay around here. So what?
I think I did say that the 5K are for radio supression......

I go by what works. I know about 1K and 5K ends with some 2K ends thrown in along the way. Mike, i ;Df you have a 40 KV coil I'm pretty sure you could use 5K ends. I'm not so sure 5K ends would do much for performance with a 13 KV standard coil as used on 230SL's and the like. The later blue coil is stronger but the CD ignition system produces a hotter spark anyway.

News:

Author Topic: Spark plug connectors (Read 16158 times)

Allenh