timing belt & spark plugs ~ which ones?
 

I'm having the timing belt & water pump replaced in a week, along with valve cover gaskets, and would like recommendations of any adjustments. So far I've ordered a Gates timing belt kit, Felpro valve gasket kit, Beck Arnley 192 thermostat and gasket, and am considering which NGK plugs to get. The recommended plugs on the NKG website and prices on Ebay are as follows:

2262 ~ copper ~ 2.59
7098 ~ platinum ~ 3.24
4363 ~ platinum ~ 9.04
2477 ~ iridium ~ 6.25

My objective is mpg, and I'm tending to the 7098's but am open to any of the upgrades. The site states both the platinums are good for fuel economy but doesn't state the same for the iridiums, just saying fuel efficiency, whatever that is.

Regarding the timing belt, should I have them stick with the OE setting? I'm quite happy with how the car's been running to this point. I'm going to have them check the head gasket too, though I never need to add any coolant. I'm tending to change the distributor cap & rotor too. I'm interested in any ideas as this is quite a bit of work to be done.

Spark plugs have next to no effect on fuel economy as long as they're working. The different types of spark plugs simply determine how long they last. Coppers go ~15k miles (all numbers are YMMV, also you can regap them to go longer). Platinums are more around 50k miles, and irridiums are good for 100k miles.

Personally, I think a lot of people have had issues with platinum plugs, so I tend to stay away from them. I get iridium if I'm going to keep the car a long time, or I go with coppers if I'm not.

I think I am running iridiums right now, just because I needed to change them and what the hell. But I keep a pair of the OEM equivalent set aside to install before emissions. You also live in Cali, so keep that in mind. Any engine changes that affect emissions will produce an automatic fail when you get the car smogged. Ignition timing is one of the things they check. I don't know about valve timing, but if they can, I'd bet they do, just to be on the safe side.

I replaced the iridium plugs in my Ranger at 130k miles. The gap was almost twice the recommendation when new, which is why I'm sure they were original. No difference in performance or economy.

regards
Mech

ngk V notch copper plugs
 

Thanks for the feedback. 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? Based on the comments, I'm getting the basic ngk copper plugs, the same ones recommended in the manual.

My sidekick requires the V grove ngks. I got the autolite xps for the insight. :thumbup:

I run iridiums as well. I doubt they do much for fuel economy, but they last a looong time. They are usually cheaper simply because they can outlast 5-6 sets of copper plugs.

My old man has a spark plug cleaner from Harbor Freight, and he pulls his iridiums at 50k and 100k miles to clean and regap. He says he usually get 150k from each set of plugs. I'm lazy, and just toss mine at 90-110k and replace.

If you pay someone to put plugs in, I'd get iridium so you can go the longest interval before having to pay a mechanic to replace them again.

However, if you're going to sell the car within the next 5 years, I'd just go copper.

You will get a CEL if one of the plugs is causing a misfire. Otherwise, the plugs won't have anything to do with MPG.

I'm not aware of any adjustment that can be done to intake/exhaust valves to get better fuel economy. My assumption is anything other than stock would get worse fuel economy. Perhaps it could be adjusted for top end power, but that would certainly hurt fuel economy.

Different engines will respond differently to changing spark plug type. I only have experience in platinum and double platinums and I really like them. If I remember correctly, iridium has a higher resistivity than platinum, so that is something to consider.

The MAJOR benefits of platinum and iridium are:

a) their resistance to ionic disintigration (electrons destructively stripping metal atoms during each "arc" firing), and...

b) their much higher MELTING temperatures.

...as compared to older nickel-iron and copper core plugs. Copper-core plugs actually DO have better electrical conductivity, but they also have much lower melting temperatures and greater ionic stripping (electrode erosion).

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.

+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.

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.

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.

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.

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

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.

I never did pulse and glide, but anyway, the savings would come more from the longer lasting of the plugs than anything else.

It was my impression that modern hydraulic valve lifters were self adjusting. Is this not the case? None of the cars I drive indicate a valve adjustment interval except for my motorcycle.

This is a Civic, right? Changing the spark plugs is the easiest thing on these. Pop the hood, there they are in a row, right on top in front of you.

My 94 had lash adjustments at recommended 30k intervals. Not sure aobut 99 but I think they still had lash adjustments.

http://www.civic-eg.com/causeforalarm/D16Y/index.php

regards
Mech

I had my then-girlfriend change the spark plugs on my Civic. If you change the wires, they always say to change one at a time, so you can keep the order correct, but I forgot that step, and we seemed to figure it out well enough.

It was amazingly easy.

Automotive Hansel & Gretel's VISUAL "bread crumb" trail: Take a picture BEFORE you take anything apart...LOTs of pictures.

A 4 cylinder is easy. It wasn't quite as easy on my 1973 Jaguar XJ12 12 cylinder. :)

JAGUAR XJ12

• The physical layout/arrangement:

A↑ (right bank: 1A..2A..3A..4A..5A..6A)

← FRONT of ENGINE

B↓ (_left bank: 1B..2B..3B..4B..5B..6B)


• The firing order: 1A..6B..5A..2B..3A..4B..6A..1B..2A..5B..4A..3B


It's really funny what seemingly useless numerical sequences a motorhead will remember, like my 340/6BBL (LA) engine: 1-8-4-3-6-5-7-2.

On my civic, platinums were -5.78mpg. Iridiums were -2.83mpg. Best were the stock v-power. Pump neutral, but butt happier with indexing.
This is on a lean burn engine that is very sensitive to spark changes. Haven't tried swapping out since I added the msd though. Can, they're near new collecting dust on the shelf.

acceleration
 

Is acceleration faster with platinum & iridium plugs?

Nope, worse. Save your money.