Spark plug color?

[1BAD68]

So I notice my 318 just started to get this little stumble at idle and when you let off the gas. I pull the plugs and all of them look good except 2.
They look brown and have an odor of like old gas you would find in a lawnmower or something.
So I pulled the distributor cap and found the rotor has a rusty colored powdery build up right on the tip.
Would this cause the spark plugs to appear like this? (see pic)

[1BAD68]

The rest of the plugs look like this...

[Budnicks]

Could be just a miss-fire causing the discoloration or maybe fuel additives that all the oil/fuel companies use now days too, just scrape off the orange colored oxidation {pretty normal} on the cap contacts & on the tip of the rotor, clean up with a little 600-1000 grit sand paper or just put a new cap & rotor on, then replace the plugs, there are pretty cheap in the scheme of things... How many miles are on the tune up ??

[1BAD68]

I'm guessing around 2000 miles since last tune up.

[Budnicks]

That's not very many miles, did you get water under the cap from pressure washing or something ??, that can cause that sometimes too, I would just buy quality tune up parts, not just the cheapest stuff, they may last a little longer... I like a cap & rotor with bronze or copper contacts, instead of the potmetal/aluminum contacts... I buy most all of my stuff from Napa or Summit or Mancini Racing too, just check the specs, before ordering or purchasing them... If it still has points style ignition, I would do the points & condenser at the same time...

[1BAD68]

as a matter of fact I did pressure wash the engine bay about 200 miles ago.
I'll take your advice and get some better quality tune up parts. The cap I installed I got from Autozone and it does have the aluminum contacts.
Thanks

[Budnicks]

as a matter of fact I did pressure wash the engine bay about 200 miles ago.
I'll take your advice and get some better quality tune up parts. The cap I installed I got from Autozone and it does have the aluminum contacts.
Thanks

    good idea

[firefighter3931]

The brass/copper contacts in the cap & rotor are much better than the aluminum which oxidizes and corrodes in a short span of time. I usually got a year out of the cheaper caps/rotors and had to replace them. 

If you still have problems with a couple plugs after the new tuneup parts are installed then you probably have an issue with the ignition wires. Get an ohm meter and measure the resistance on your plug wires/coil wire. Ideally you should have less than 250ohms of resistance per foot of length. 


Ron

[Budnicks]

If you still have problems with a couple plugs after the new tuneup parts are installed then you probably have an issue with the ignition wires. Get an ohm meter and measure the resistance on your plug wires/coil wire. Ideally you should have less than 250ohms of resistance per foot of length. 


Ron

Thanks that's very well said, that was the next thing, I was going to suggest is getting new plug wires & Ultra Low OHM resistance as possible, lower the better... It's money well spent either way, even on a stock lowly 225ci /6 street cruiser or a 572ci beheamith...