Iridium Spark Plugs

[charles p]

Iridium plugs made an old mower engine run like new.  I was so impressed I bought some for every small engine I have, though I have not yet tried them in anything but the lawnmower.
Are they hype or for real?  What about using them in large engines or outboards?
Can the spark from a plug be too good?

[Larry L]

Iridium plugs have a much smaller center electrode. As such, it takes far less current to make the spark. Usually the spark kernel is larger and hotter than a plain metallic plug. Iridium is stronger than platinum and will stay cleaner than any other type providing you haven't changed the plugs temperature. Running one too cold will eventually foul. Iridium will stand up to far hotter combustion temps than any plug- 1200F more than platinum or better said, the pistons will be molten before the plug electrode gives up. The only engine I would never use them in is one running E85 or a blown alcohol engine. The tip of the plugs run too hot and detonation can be an issue. They are for real but they are also not a cheap date. For most engines, there is very little performance gain for the dollars spent but may make a weak ignition engine run like a champ.

[Ranger99]

clean the rust patches off your
flywheel and check the coil gap
and key on your mower.
a regular plug should
work good and give a good spark.
iridium is kinda pricey for a
mower or the like.

[Lloyd Smale]

I thought they were a gimic myself until i bought some for my jeep on the recomendation of the guys on one of the jeep fourms. The little 4cly would allways buck going up the hill on the way to town because its so underpowered and after the plug swap it would make the hill without a hicup. Id swear you could actually feel the differnce in the seat of your pants driving it after the swap.

[Bugflipper]

I was having trouble with a 50's tiller being a pain in the butt. No real replacement parts for the motor. I just cleaned the magneto and so on. Rebuilt the carb and it still spit, hesitated and sputtered. Sounded just like a harley. I put in an iridium plug and it ran like a top after. A lot of folks say it's a bandaid instead of addressing the real problem. But it's easier to replace a plug than to tear apart the engine and spend half a day pissing around with it.

[1sourdough]

 I put an iridium plug(2) in my Cub Cadet this Spring, the old Champion plugs were acting up. It was about like night to day, the engine had recently developed starting issues, totally gone.

  I won't go out & get them for everything, but will consider them when other plugs are coming up short.

[geezerbiker]

Bosch Platinum plugs will do the same for a lot less money.  I think the iridium is a gimmick on an otherwise standard design of a high performance spark plug.  Before iridium, there was platinum and before that there was gold palladium.

Tony

[mechanic]

The iridium is not a gimmick.  In our overhead cam forklift engines, it saves a lot of money on service calls.  The mfg. recommends them, and if we go cheap and replace them with something else, we'll be out in a few weeks changing them back.  They are usually good for about 8,000 hours as we use them.  We periodically clean and regap.

That's about 400,000 miles on an auto.

Ben

[Bob Riebe]

I bought my first Iridium plugs for my bike back in 1978, they are not new or a gimmick.

[geezerbiker]

Try Bosch platinum plugs and you'll find they do the same for less money.  BTW, somewhere in my junk I have a NOS Firestone spark plug from preWWII that according to the box has a plutonium tip.  Gimmicks in spark plugs goes way back...

Tony

[Bob Riebe]

Try Bosch platinum plugs and you'll find they do the same for less money.  BTW, somewhere in my junk I have a NOS Firestone spark plug from preWWII that according to the box has a plutonium tip.  Gimmicks in spark plugs goes way back...

Tony

If you are going to go that route, then standard plugs, especially if given a little file work for more "spark", are really all that is necessary, plus you can change them more often and not spend any more money.

[Bugflipper]

Beware that platinum actually has more resistance than even the cheapest copper plugs. The selling point is platinum lasts much longer so folks don't have to change plugs as often. With modern electronic ignitions it's no big deal as the spark output is much more than actually needed. On a struggling magneto system platinum wouldn't be the best option.

[oldandslow]

I don't have a clue how well replacing iridium plugs with platnum plugs would work and don't intend to find out. The iridium ones aren't all that expensive considering how long they last.

Wife's previous SUV's owner's manual specified in large capital letters to use only iridium plugs and change them at 120,000 miles. I finally got around to changing them at 140,000. I keep gas mileage records and hadn't had any drop in mileage but decided to change them anyway. It made no difference in the car's performance at all. Her current SUV is the same brand and has the same plug specs as the previous one. I'm going to run the plugs until I notice some performance drop off to warrant a plug change.

[charles p]

Wife's Lexus specifies Iridium plugs.  My small engines all love them and crank much easier.