I replaced my stock spark plug with an NGK Iridium (CR8EIX) today. I checked the gap which was .025 and the spec is a .028. But I put it in as is and it seems to run fine.

As do most I like to read the old plug after removal. It looks good to me for only 2,900 miles. I also found this cool comparison chart for spark plugs.

 

It's harder to read spark plugs today. Fuels, cleaner running combustion chambers, and better ignitions seem to make any plug that's running even close to optimum look about the same. It's only when they're running fairly rich that you can see that. On your spark plug gap, there are some decent gapping tools that allow you to alter the ground strap distance without any damage. I like to achieve maximum gap when possible to provide the widest spark.

 

Ya, that was my fear. All I have is a coin gage and I didn't want to bust off the tip trying to bend it back. If I notice any decrease in performance I'll fix it.

 

I just put an NGK Iridium plug in my engine when I put it back together. I actually put in a plug that is one grade cooler than stock. I used a CR9EIX I went with the cooler plug because my engine was occasionally pre detonating when hot , and at low low rpms.
When I checked the gap on mine it was right in there at .030 (manual calls for .027-.031)
Old plug I pulled out looked pretty good. I'll get a pic and post it up.
Dan

 

I usually set my plugs on the tight end. Better to run toward optimum than to run away from it. You want to see some discoloration of at least half the ground strap to insure it's self-cleaning. Can't tell for sure, but yours looks pretty good to me.

 

Your precious metal plugs don't wear away like conventional plugs, so you don't have to factor in the wear issue. I just pulled a set of near 100,000 mile plugs from wife's HHR 2.4 Ecotech 4-banger, and they were dual platinum AC's. The plug gap was still at factory spec.

I sold an '89 GMC full size Jimmy 4X4 last with over 300,000 miles on it. I always ran precious metal dual tipped plugs in the stroked 383 engine in it. I ran a slightly bigger gap than recommended with a combination Accel and MSD aftermarket modded ignition...much hotter spark and they were multiple sparks also on each firing. I changed plugs over time out of guilt on that engine, but the gap always stayed consistent. Very impressive, and this has been my experience over many vehicles over time. These precious metal plugs don't add power or ignition performance to an engine by themselves. They do, however, maintain the quality of the ignition performance for much, much longer than most any conventional plug. Engines don't produce the level of deposits like they used to back in the day, but the ignition/combustion process will still eat away at a conventional plug's firing contact points more quickly.

 

On the issue of spark plugs...since most of us actually get our hands dirty with maintenance and mechanical....I'll pass along this rebate link. Mostly for 4-wheels instead of 2, but maybe you guys can use it....

Save your receipt: Bosch offers spark plug rebate program - Automotive Service Professional

 

Speaking of multi tipped plugs...
I did some undergraduate work at school years ago and did some testing with different plugs. The multi tip plugs rarely had multiple sparks. The shortest path to ground usually won.

 

True, if you're talking about those plugs with more than one ground strap. Spark is only going to jump across one ground strap. When I say dual tipped plugs, I'm referring to the fact that there's a precious metal contact on the single ground strap and also one on the center electrode...in other words, a precious metal to precious metal spark contact point which is why they don't erode very quickly. Multi-ground strap plugs are a bit of a marketing ploy IMO.

 

Not really. Multi-ground plugs do serve a specific purpose and that's to provide more than one useful spark gap. That way if one is more fouled or eroded than the other you still get a good spark. They also wear slower than regular plugs.
Multi-grounds, like Golden Lodge, were very big before rare earth metal tips became popular because of their longevity. A friend of mine used to own Alpha Romeos. One in particular, and Alpha-Sud Ti, used those quad electrode Golden Lodge plugs. He tried regular plugs in it, good ones at that, and they lasted under a thousand Ks. When he checked why the car was running like crap, besides it being a Friday and due for it's weekly tune-up the side electrodes were all but GONE. These days you'd just use platinum or Iridium plugs, but this was before they were available. That Sud also had an 80KV coil output. Vicious little thing it was.