For a 1995 3.4L Which plugs? NGK V-Power? or Iridium or Platinum & why? I have heard that it is best to stay with the base plugs, but have not heard any real reasoning...

Thanks in advance.

 

The car uses waste spark DIS ignition, which means 3 plugs fire from the center electrode to ground, and the other 3 fire from ground to center electrode. No big deal except that 3 plugs are going to erode the center electrode faster than the ground electrode, while the other 3 are going erode the ground electrode faster than than the center electrode. This means nothing if you are using regular plugs, or plugs that have both electrodes tipped,because all 6 plugs will wear out one way or the other in the same amount of time. However, if you use plugs that only have the center electrode tipped, 3 plugs will last a very long time, while the other 3 will only last about 1/2 as long.
If the car is stock, the best engine performance will be achieved by using the same plugs that the factory put in when the car was built. (AC.R43TSK gapped at 0.045"). The reason being that the plugs were especially made for the engine. Substitute plugs are made to cover a variety of engines, and consequently do not have the exact heat range. If the car is modified you will have to experiment with the heat range. For longer plug life either iridium or platinum will work as long as both electrodes are tipped. The iridium are easier to fire, but have been known to actually lose the tips in high performance engines, the platinum are more reliable but are harder to fire. The ignition system for your car is designed to use standard type plugs without precious metal tips.

 

Thanks for the details! So do you know what the advantage is to DIS Ignition, if any?

Sounds like you are saying that many plugs have only the center coated, and not the side electrode? Many manufacturers give little details on their products -- might be hard to tell...

In my case, the '95 3.4L has a high-flow CAT, performance Flo-Pro muffler and SLP CAI -- my guess is that this setup is still close enough to stock not to make a difference in plug selection?

 

The advantage of DIS is no moving parts, and no distributor. Anytime you can do away with a moving part and replace it with an elctronic circuit,it is a big advantage. Most tipped plugs only tip the center electrode, but there are plugs sold with both electrodes tipped (dual platinum). Your engine is still pretty close to stock, so the stock plugs should work fine. You start having problems when increasing displacement, changing compression ratio, changing camshaft. Usually, but not always, a modified engine runs better using colder plugs. Really need to look at the insulator & go from there.

 

So do the iridium or platinums have the tipped plugs or whatever... are they ok to use in the car?

 

You can use them, and they will work OK,but if they don't have both electrodes tipped, you are wasting your money, and might as well put in regular plugs, just like the factory did. Otherwise, double tipped plugs should last for at least 75K miles, which is probably more than the life left on the engine. As far as I can tell no one is making double iridium plugs, but that could easily be wrong.

Autolite Double Platinum info:
http://www.power-21.com/honeywellpow...x?b=A&vt=1

Champion Double Platinum info:
http://www.federal-mogul.com/en/Afte...PlatinumPower/

NGK Info:
http://www.ngk.com/sparkplug411.asp?...num&mfid=1

AC Info:
http://www.acdelco.com/parts/sparkpl...l-platinum.jsp