Spark Plugs

You do have to check the gap, but the plugs also wear out faster and have to be replaced more often. I don't know how long they last because I have changed mine several times trying out different options. I haven't kept them in long enough for them to wear out.

The OEM plugs have an iridium tip and a platinum spot on the ground. Because iridium and platinum are very hard these plugs last a long time, but platinum also has higher resistance and doesn't provide as good of a spark.

The 7E plugs have a nickel tip and a nickel ground. Nickel is very soft and wears out quickly. However, some people believe these are better than the iridium versions. One reason is that they have a larger surface area on the tip, which might give a better spark. The NGK website rates these lower performance than the EIX plugs. I personally think the NGK engineers know what they are doing, so I believe them. Other people might disagree.

The EIX plugs have an iridium tip and a nickel ground. The tip lasts longer, and iridium has lower resistance than nickel. The tip is a very fine point. The nickel ground will wear out as quickly as the 7E plugs.

With either of those plugs you will notice that the ground will get a large pit in it after a while. With the 7E plugs you may also see wear on the tip.

Also, try to gap all four plugs as identically as possible. And, if you use the EIX plugs, be careful not to break the tips. Don't put pressure on the tip. My car runs much better at 0.28 than at 0.30.

Ha, an old GM 455 CID would get you home if only 3 or 4 out of 8 plugs were firing and most people didn't even know the difference. Sure didn't have to worry about burning up your catalytic converter, didn't have any. PCV wasn't a problem returning crap back to the combustion chamber, because returned to a bare intake manifold. no injectors in there to have their faces plugged up with carbon. And the AF ratio for each cylinder would remain the same because there was no O2 sensor to go nuts with the new stuff.

One little misfire, O2 sensors, oh my God, seeing oxygen, the fuel must be lean, better enrich it, so even more raw gas goes into the cat to burn it up. Talk about a self destructive machine.

When spark plug wires were used, some were over three feet long generating lots of EMI where the major inference was with an AM radio, screw the radio, want a hot spark so would use solid copper wires. What they were doing was taking a piece of grocery store string and dipping this in carbon that with engine heat would cake up and causing arcing within the carbon. This was where your spark was going certainly not across the electrodes in the plugs where it belongs.

But with my 454 left that carbon in there idiots were using an insulation displacement spark plug terminal just making a point contact at one point to that carbon, how stupid can you get? So on each end of each wire, jammed in a piece of 20 AWG plated single strand wire two inches into the carbon to vastly improve the conductivity. Resistance of this wire was 2K ohms per foot, made darn sure a three foot wire was 6k ohms, and this was checked every time I had to clean or replace the plugs.

And this was quite frequent because back then not only had conductive carbon on that center electrode insulator shorting the plug to ground but lead as well, new plugs were about 40 cents each back then. Least now, just carbon, also cleans off much easier, use walnut shell powder in my blaster to clean them. To deal with PCV dump in a can of Seafoam in a full tank of gas every 5K to clean up that carbon. But instead of doing this around every 4K miles, getting by with 15K miles now, and only use top tier gas.

Who ever gets my Cruze will find four brand new plugs in it, just replaced the before it was rear ended, I don't get it back, insurance company gets to keep it thanks to our crooked laws protecting the insurance companies, and screw you consumer.

Never shed a tear when spark plug wires disappeared, one less problem to deal with, but sure prefer coil on plug over the module, if one is bad, just replace that, not the entire module. But carbon has not disappeared in that wire, was moved inside of the plug and does anybody check that resistance between the center of the electrode and the outside terminal? this kid does, should be 4,000 ohms, for all you know since you cannot see it, could be infinity.

Daughter's Kia has coil on plug, nice, but some idiot specified a 45 mil gap, didn't know they had crack in Korea. This was tricking trying to close a 45 mil gap down to 26, had to very carefully bend the ground electrode outward while closing the gap so those two infinitesimal iridium electrodes were in line. Paid off, averaging 5 mpg more in fuel economy and seeing power she never have before with that little 1.6 L. And her fuel is being burned in the combustion chamber and not in the cat, even more problems.

18 ft-lbs of torque is darn near standard, if using a six inch wrench, that jumps up to 36 pounds of force, not easy to judge, if you don't have a torque wrench, get one, but not a cheap piece of crap, get a good one. Still prefer analog, hate these clickers, when you hear that crack not sure if its the wrench or your head that cracked.

Springs inside the boots are a problem, get hung up on the shoulder in the boot, stretching them out about 3/8" solves this, or will have a heck of a gap in there. Need a very bright light, tipping the module toward you, make sure all four boots are centered over the four plugs, then tip it backwards while applying pressure.

One more thing, is you see carbon on the spark plug washer, getting blowby and if its there, also on the seat in the head. Have to attach a piece of lint free cloth to a wooden dowel, soak it in choke and carb cleaner and clean that off. If you don't, will never get a good seal.

Won't get into what kind of plug to use, too many different opinions on this subject and most of them are from guys that have not designed ignition systems for the last 40 years.

These are hundred year old spark plugs from a Ford Model T, ha, really haven't changed that much.



Actually this fired very good, Ford used permanent magnets on the flywheel that generated a voltage that operated a relay wired like a door bell buzzer, so would get a series of sparks. But the major problem was contact wear on those vibrator contacts, not spark at all.

Kettering came along using battery voltage with an autotransformer and camshaft controlled ignition points, a capacitor was connected across the points and renamed the condenser. This was so bad either, because when the points open, that condenser would form a resonant circuit with the coil, so would get a series of sparks. But again, point wear.

This lasted until the 1972 model year where a transistor replaced the points, but unlike the points is a unidirection device, cannot take reverse polarity like points can, so that condenser had to go. The consequence of this is only getting just one spark. Using an SCR to drive a capacitor charged to 400 volts and discharging it through the coil generates a nice spark line. But way too expensive for the bean counters, also requires an inverter, so just living with one quick spark.

Cars are still burning carbon that is highly conductive on that center electrode insulator, in brief, grounds out that center electrode voltage to ground. So not only just one spark, but one that can also be grounded with no spark at all.

Looking at over a hundred year problem with spark plugs that still never yet was solved, well the diesel did, no spark plugs at all.

If you really want to keep your spark plugs cleaned and gapped properly, you have to do this yourself. One key reason why I really like a four cylinder engine. Ha, that Caddy V-16 I owned was a major job, all I had was an Exaxto knife and a piece of steel wool, in the 60's making a couple of bucks purchased a walnut shell blaster to ease this job, still have it.

Putting V-6's or 8's in a FWD was crazy, had to tip the engine, or remove a bunch of stuff even to find the plugs. Or mounting an AC compressor over a couple of plugs, another PITA to deal with. Is an absolute pleasure to clean or replace the plugs in the Cruze. But they still have to be cleaned and properly gapped.

With copper type plugs for years, could get more mileage out of them with a super fine file. tip of the electrodes had to be perfectly square with sharp corners to get a decent spark, basics of electrostatics. Platinum or iridium kind of solved this problem.