Double Platinum Spark Plugs

[Cuplable]

So, it time to change the spark plugs on the 'ole 3.4L Impala. I know that the shop manual calls for platinum plugs...but I'm considering double platinum plugs. My question is: Are they worth it? In theory, I believe they would be better. Platinum on both sides of the spark seems to make since to me. And, it's only a buck more per plug ($6 total). Nothing that will break the bank. I do plan on running this car til the wheels fall off....or I win the lotto, which ever comes first.

Any insight or links to other material is welcome and appreciated.

 

[Matt_S]

GM used double platinum plugs as OE for a number of years, although they've switched to iridium now. Apparently the reason is their waste spark ignition system that fires two cylinders each time the coil discharges, doubling the number of sparks that each plug sees. There was a problem with these plugs though, in that the platinum disc that was laser welded to the ground electrode would tend to break off. This would increase the gap and sometimes cause idle problems, missing, rough running, etc. I've never heard of anyone claim mechanical damage. IMO, the center electrode is really where you have to worry about wear, though.

 

[Dominic]

I recommend getting the Denso iridiums. You can find them under an AC-Delco part number as theyre now becomming factory stock in many new cars. Im running the 41-101s in my 3.8 and theyre fantastic.

 

[Kestas]

Don't worry about mechanical damage from the platinum pads breaking off. The metal is incredibly soft, softer than many plastics.

 

[punisher]

Get iridiums or double platinums. Double platinum plugs are the norm for waste spark systems. Ford used to have 2 different types of plugs used/mixed on the same engine, platinum ground (PG) and platinum electrode(PE). They finally went to double platinum (PP suffix). The reason for double platinums is because you can put a platinum plug on the wrong side of the coil on a waste spark system, ie you can install a platinum ground plug in place of a platinum electrode plug and have excessive gap erosion.

 

[road_rascal]

Fords are weird. The front plugs on my '01 Windstar were single plats when I pulled them out and the rear bank had double plats.

 

[BlownF150]

Sounds like your van just caught the end of a batch or something. My truck came with Motorcraft platinum plugs. I now use colder NGK copper plugs as neither platinum or iridium plugs are terribly happy with higher boost pressures. The NGK's I use do very well in 1200hp+ drag radial cars though.

 

[mechtech]

Double plats are the replacement for the switched plat tips on stock plugs.
Waste spark ignitions save a few cents [times thousands] with the plat on only one or the other side, from the factory.
Use the double plats, and be happy.

 

[SHOZ]

quote:

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Originally posted by road_rascal:
Fords are weird. The front plugs on my '01 Windstar were single plats when I pulled them out and the rear bank had double plats.

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That's because of the waste spark design. The front bank gets a positive change which fires down through the plug to the block. The rear bank gets a negative charge which fires up through the plug to the coil.


If you change plugs once a year or so then copper plugs are a better choice.