How easy/difficult to change spark plugs in a '98 GT (non-cobra)?

Do you have any mods?

On the 4.6L 2V engine, the gap should be set at 0.054" with a stock ignition

I firmly believe on a stock motor with that many miles, Autolites are more than sufficient.... If you want a little more performance from your plugs don't be fooled by these Bosche paltinums, and NGK's...I've tried them all and seen the numbers on the dyno even, and Autolite Single-Platinum plugs are the best and its just a bonus that they are the least expensive. Don't be retarded like me and spend $60.00 on spark plugs.

if you dont have any serious mods(blower, nitrous, etc.) just use some Autolite 764 coppers gapped to .054". .054" is the stock gap. its fairly easy to swap the plugs, i made up a huge writeup on 99+ stangs to change them, but the only difference is you also have plug wires and coil packs.

70stangcoupe said:

Do you have any mods?

Click to expand...

This is very important! DO NOT use Bosch Quad-Platinum plugs if you have a hot aftermarket ignition already. Those plugs burn HOT.

Here just read this if you got the time:

Now on a supercharged, nitrous oxide injected or turbocharged engine, your cylinder pressures are much higher than a naturally aspirated engine. As cylinder pressure increases, the energy needed to jump the gap between electrodes does too. Unfortunately, the stock ignition isn't powerful enough to provide the additional spark voltage required to jump the gap. Effectively, you are blowing the spark out under boost or when the nitrous is applied. Most people simply reduce the gap on the spark plug when boost is a factor in the equation. This means the distance the spark has to jump is reduced and the resistance has dropped. On the 4.6L engine with 6-10 psi of boost, you can get away with a gap between 0.035-0.040". More than 10 psi of boost is pushing the limits of the stock ignition and you really need to upgrade to a more powerful voltage supply. MSD makes an MSD DIS-4 system to do just this. The lower the gap setting, the less power you will make though. Ideally, with a blower, you want to run as close to the stock gap as possible. This cannot always be done and with the stock 4.6L ignitions it's down right impossible. There is another solution though.



Denso makes an iridium type sparkplug with a tiny "u" groove channel in the ground electrode. Some of you smarter types may have noticed the similarities between the Lightning FM1 plug and the Denso iridium plugs. The iridium makes the tip of the electrode very hard. The manufacturers are able to reduce the overall diameter of the center electrode, making the tip, very thin and to a point. This dramatically reduces the voltage required to jump the gap. As we all know, electricity flows to the path of least resistance. So with a larger gap and a supercharged engine, you picked up power. The power did not come from the spark plug itself, but rather from the larger gap area that provided a larger flame kernel. The material and electrode size allowed the plug to be gapped at the stock specifications under extreme cylinder pressure situations.



A wise man has told us over and over again, use the Lightning plugs on any supercharged 4.6L or 5.4L engine. Now you understand why. Not only are they able to transfer heat faster than a stock spark plug, the newer FM1 plugs can reduce the resistance and reduce the chances of misfires on a supercharged or nitrous application.





CONCLUSION



Once again. Stock 4.6L spark plugs:



AWSF-32C

AWSF-32PP



One heat range colder than stock:



AWSF-22C (medium wire electrode, copper)



Two heat ranges colder than stock:



AWSFA-12C (medium wire electrode, copper) Application withheld.



Platinum choices two heat ranges colder than stock:



THESE ARE LIGHTNING EQUIPPED SPARK PLUGS

'99-'00 used AGSF-12EE (medium wire electrode) half thread

'01-present use AGSF-12FM1 (fine wire electrode) full thread



Yes they will work in any 4.6L and 5.4L engine as well as the older 3.8L Supercoupe engines. Also, these plugs are not to be used as a band aid for running lower than required octane rated gasoline's in your engines. That's working against yourself. Go as low as you can with the octane rating before it pings then move up a step (RON number). You will make the most power there. Running 100 octane gasoline in your stock '96 Crown Victoria is a waste of money. If you are running a chip or other means to advance the spark timing, then you may need to run 93 or higher octane. Combine that with the colder plugs and a lower temperature thermostat, you have dramatically reduced the engine from being knock constrained.







Furthermore, the colder plugs DO NOT offer a power increase by themselves nor do increase/decrease the voltage requirement, durability or performance, they can help you make more power. A wise old man once told me about a plug that was two heat ranges colder than stock in the AWSF family. I found the part number and posted it a few years ago. So here we are full circle, from the tip of the wise man you can enjoy more power without harmful detonation.





So the bottom line is, use one heat range colder than stock if you abuse the car or see WOT often. If you have a chip that adds timing, drop two heat ranges. This is up to you, but we all agree it's a better solution to use two heat ranges colder than stock. If you are supercharged or run nitrous oxide, this is a no-brainer, go with Lightning plugs or AWSFA-12C.



I hope this helps and enjoy.