I just had the dealer change plugs on my Hemi. I asked them to label them for me and half the cylinders have really white looking plugs (both) half look what I would call normal light brown. Is this something to do with MDS or could it be clogged injectors, it doesn't run as smoothly as it used to.

 

I think (someone will crack in with better info) that they use a different material for the top vs the bottom, I think the bottom plugs last alot longer than the top

 

Could you post up a pic of a plug so we can actually see what you are attempting to describe?
The bottom of the ceramic is always gonna be white and towards the top will get brown. Top half should be brown.
If the tips are white, that means lean conditions.
A pic would really help bud. also, what plugs were white? i ean what cylinders? very possible they could be from the mds, but they shouldn't be chalk white ever.

 

If I understand what you're saying, you mean the electrodes are white, or light brown? Either color is fine, so long as it's not in excess. This page gives you a breakdown of the colors and conditions. White is normal, it kind of depends on the gas you buy, the stuff you add to the tank, and sometimes the region you live in.

http://www.classictruckshop.com/club...park/plugs.htm

 

There are no top or bottom plugs. Same plug in every socket, all changed at the same time. Unless they labeled them more specifically, "cylinder 1 front", "cylinder 1 rear", etc., this may be hard to track down. Are the electrodes burned?

 

The plugs that fire on the wast (or Exhaust stroke) will look white as the cylinder is very lean on the exhaust.

As for not running great after a plug change. Maybe they did not check the gap on the new plugs. I call it "box gap plugs" its like a box of chocolates you never know what your going to get.

 

ohh mike, i figured it was like the 4.7 which has a set of top plugs to be changed at 30 and bottoms at 50

 

That makes sense. I've already pitched the plugs from my C, and I can't remember if they showed that color mix.

Actually, I believe the "two-plug" 4.7s are 30K and 90K (may be 102K).

**EDIT** Here is a pic from the plug change on my C. Not a radical difference between the front and rear plugs...

 

Not sure why I was quoted in your post.

 

I'm pretty sure it was because he was agreeing with you and backing up your statement, however; I don't see the plugs being burnt any different than another. They are both located within the same combustion chamber, it's just that one plug fires a split second after the other. Both plugs within the same cylinder means both plugs are subject to the same heat and explosions regardless which one fired first.

As far as the 4.7L's dual spark plug thepry...where are you guys getting this from??
Is this something new on the newer 4.7L heads? i still don't see one plug lasting longer than another either???
Please school me if I'm misunderstood regarding the 4.7L's, I love learning!!!