timing belt & spark plugs ~ which ones?

[Xist]

Don't platinum and iridium plugs still contain copper?

[gone-ot]

Originally Posted by Xist

Don't platinum and iridium plugs still contain copper?

Some do, but it's WITHIN the upper area of the spark plug, not down at the center electrode inside the combustion chamber.

[Fat Charlie]

Originally Posted by ksa8907

Different engines will respond differently to changing spark plug type.

+1

Exact OE replacement is the best way to avoid offending the car's machine spirit. Don't go to the dealer, just find the exact one the factory used.

[cRiPpLe_rOoStEr]

Originally Posted by johnlvs2run

It seems to me the faster acceleration with platinum or iridium plugs would result in shorter pulses for each coast, and thereby better mileage. If not, then they must burn more gas to get the faster acceleration, which becomes a tradeoff. Why would iridium plugs increase emissions or affect valve timing?

Actually, iridium plugs would burn the same amount of fuel more efficiently, then it would lead to faster acceleration, it doesn't have nothing to do with valve timing. And wouldn't actually increase emissions.

[j12piprius]

Originally Posted by cRiPpLe_rOoStEr

Actually, iridium plugs would burn the same amount of fuel more efficiently, then it would lead to faster acceleration, it doesn't have nothing to do with valve timing. And wouldn't actually increase emissions.

Well then the iridium plugs would increase mpg, due to faster pulses vs distance of coasting.

[Daox]

Changing plug types will not increase or decrease your mileage a noticeable amount.

[mikeyjd]

Originally Posted by Daox

Changing plug types will not increase or decrease your mileage a noticeable amount.

Has this been tested thoroughly? There seems to be conflicting opinions, and I'm just wondering if you know of any good data on this.

[gone-ot]

IF the spark plugs WORK in the first place, there is NOTHING to be gained--or--lost by switching to exotic-metal plugs.

The ONLY thing these metals do is LAST longer (~100K miles) & more reliably (EPA emissions) than "normal" plugs because of their much higher melting temperatures and much lower ionic erosion(*)...even WITH their much smaller diameter size.

Melting points:

4,436ºF - Iridium
3,215ºF - Platinum
2,618-2,582ºF - Nickel-Iron


(*) = EPA-mandated 100K "life" for emission-related components, etc.

[user removed]

I always used (in my shop) what came in the vehicle to eliminate the possibility of making it run worse. After what I experienced with the Ranger's plugs (earlier post), I see no reason to not use a plug that lasts 3 times longer. While you can run plugs far past their recommended intervals, I believe that places additional stress on the rest of the ignition system (potential failures increase), when gaps are allowed to grow larger. I've seen 100 + K on conventional factory installed plugs in Nissans, I would not recommend you run plugs 300% of their recommended intervals, but I would not hesitate to run my Fiesta and the Ranger to 100 k intervals oin their iridium plugs. It's more cost effective to run iridiums IF you plan to drive your car to 100k. If your goal is 30k go with OE and make sure you adjust the valves if your're going to pull the cover anyway. I like to break the lock (valve adjustment) nut and then use my finger to tension the threaded part unitl I feel a specific resistance on the widest gap feeler gauge, thne hold the shaft and tighten the lock nut, and recheck the gap. My old (sold) VX was in specs at 62k miles, valves had never been adjusted.

regards
Mech

[ksa8907]

All plugs have copper cores, the electrode is what changes.

I have personally seen single platinum plugs with roughly 60k miles, the gap went to about .070" just from the ground being blasted away. The elecrode tip was fine.