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post #1 of 9 (permalink) Old 08-17-2013, 08:23 PM Thread Starter
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first and second carb

Hi,
in order to adjust the valves i removed the spark plugs and noticed something interesting.
the first three plugs from the front are clean and white while the other three are black.

What does this mean?
the carbs are not set properly or?

from the left is front of the engine and back to the right.
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post #2 of 9 (permalink) Old 08-18-2013, 06:17 AM
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Yes.

First things first. Get the vacuum issues resolved. You are not going to get a good sync until you have proper, even air flow.

Second. You do not want resistor plugs if you are using the stock replacement wires. They have built-in resistance and the use of resistor plugs reduces the spark.

The plugs can wait but remember this the next time you change them.
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post #3 of 9 (permalink) Old 08-18-2013, 07:08 AM Thread Starter
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I had platinum plugs and the engine worked like shit
With Luna we have the same plugs
If these are not correct plugs what are the correct plugs?
Thank you


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post #4 of 9 (permalink) Old 08-18-2013, 07:13 AM
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Nothing wrong with the Champions, just get the non-resistor versions next time. Same plug number minus the "R".

Don't you ever sleep?
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post #5 of 9 (permalink) Old 08-18-2013, 09:01 AM
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Originally Posted by kavadarci View Post
I had platinum plugs and the engine worked like shit
With Luna we have the same plugs
If these are not correct plugs what are the correct plugs?
Thank you


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Platinum plugs are a no-no in Mercedes. There are even service bulletins in this regards for some models.

Use a Bosch or Champion (I prefer Bosch as they are the OE supplier) plain copper plugs, nothing fancy. And no resistor plugs, either.

As the previous poster suggested, if you have vacuum issues they have to be sorted out before you can do anything else. Vacuum leaks will wreak havoc with the Zeniths and make them and the ignition system near impossible to sort out.

Dan
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post #6 of 9 (permalink) Old 08-18-2013, 10:25 AM
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"Platinum plugs are a no-no in Mercedes. There are even service bulletins in this regards for some models."

Dan,

I have read comments like like that on various car forums aimed at every brand of plug I can think of. What is the actual reason why a particular electrode material (platinum) would be harmful in an engine from one manufacturer but not others?

I first got interested in Bosch platinum plugs when I found out that UPS had converted their fleet. I then ran them for years in the Mopar small block engine in my Dodge van with both point and electronic ignition.

In the 1980s one of the motorcycle racer magazines tested spark plugs in a race engine on a dyno and on the track and found no measurable difference. They concluded that racers should "Buy the spark plugs that perform best at the cash register".

Another motorcycle related myth that is out there is that the bikes need different oil than cars/trucks. I'd bet the ranch that the only diffenrence is the can the oil is in.

Ray
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post #7 of 9 (permalink) Old 08-18-2013, 12:42 PM
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LWB250,

I installed a HotSpark ignition with an after market coil. With this coil, do you still recommend that I should NOT use resistor plugs? The problem that I was having was finding copper plugs that have the threaded end where the wires plug onto. BTW, the engine is running very strong with no signs of lack of power to the engine.

Here are the specs on the coil:


Ideal for use with 6-cylinder or 8-cylinder electronic ignition or with points

More turns of copper wire than other standard-sized canister coils

High secondary resistance (10K Ohms) sends as much as 45,000 volts to the spark plugs

Heavy-duty, high-energy coil

Standard 56mm X 112mm (2.2 in. X 4.4 in.) canister size - fits stock-sized coil clamp

Primary resistance: 1.7 Ohms

Secondary resistance: 10K Ohms

Turn ratio 143:1

Primary inductance 2.36 mH

Secondary inductance 33-38 H

Solid, epoxy-filled canister (not oil-filled) for high-vibration environments

Three-way 1/4" brass male connectors on both terminals

Rugged, mirror-polished, non-corrosive case won't chip or peel over time, like chrome-plated coil canisters

Designed specifically to produce maximum spark with Hot-Spark electronic ignition or points.

Last edited by Luna Gaudi's 72 250; 08-18-2013 at 12:44 PM.
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post #8 of 9 (permalink) Old 08-18-2013, 03:47 PM
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Quote:
Originally Posted by Waldbaum View Post
"Platinum plugs are a no-no in Mercedes. There are even service bulletins in this regards for some models."

Dan,

I have read comments like like that on various car forums aimed at every brand of plug I can think of. What is the actual reason why a particular electrode material (platinum) would be harmful in an engine from one manufacturer but not others?

I first got interested in Bosch platinum plugs when I found out that UPS had converted their fleet. I then ran them for years in the Mopar small block engine in my Dodge van with both point and electronic ignition.

In the 1980s one of the motorcycle racer magazines tested spark plugs in a race engine on a dyno and on the track and found no measurable difference. They concluded that racers should "Buy the spark plugs that perform best at the cash register".

Another motorcycle related myth that is out there is that the bikes need different oil than cars/trucks. I'd bet the ranch that the only diffenrence is the can the oil is in.

Ray
Ray,

Please don't take my comments and misstate them. I did not say anything about platinum plugs being harmful. I stated that Mercedes has issued service bulletins regarding the use of platinum plugs in some of their cars and that they should not be used. The service bulletins I saw (and I can try and dig a copy up) pertained to the use of platinum plugs in the W124 chassis cars using the 3.0 liter inline six engine. The complaint was that they cause rough and unstable idle. There was no statement that damage would result from their use, but that there was an issue of performance.

As for using them in any other car/engine, my approach, as a former NIASE certified mechanic who used to make a living working on high line cars, is to use what is recommended by the manufacturer.

Platinum plugs are by no means new to the automotive industry. That being the case, if they provided a performance boost or were better for a given car/engine, the OEM would have installed them.

Luna, as for your aftermarket ignition, I would contact the manufacturer and see if they have specific recommendations. If not, I would continue to use what MB spec'ed in the engine - standard copper electrode Bosch (or equivalent) plugs. To put anything else in the engine is a waste of money.

Dan
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post #9 of 9 (permalink) Old 08-18-2013, 03:52 PM
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Quote:
Originally Posted by Waldbaum View Post
"Platinum plugs are a no-no in Mercedes. There are even service bulletins in this regards for some models."

I have read comments like like that on various car forums aimed at every brand of plug I can think of. What is the actual reason why a particular electrode material (platinum) would be harmful in an engine from one manufacturer but not others?
Not sure if I'm adding to urban legend or not, but I was told that the platinum ran hotter than their counterparts, and would destroy the piston top in 10,000 miles or less. I ran platinums for eons and never had an issue, but to be fair to urban legends, I've never had the engine apart to inspect them.

I've also heard, often, that if you have a degraded ring set in one piston, to use platinums to burn off any oil deposits...

I'd love to hear a good, scientifically-based reason myself.
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