Spark Plug recommendations for 1980/81 Cordoba/Mirada 318-4BBL

kkritsilas

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Just wanted opinions on the right plugs to use with the 2 J bodies that I have. The plug that is called out is a Champion RN-14YC (going from memory here, so that may not be correct) in the owner's manual. Is there any advantage, on our carburated cars to use anything else? I know the iridium plugs are almost mandatory for turbocharged or supercharged cars (which my cars are not), but pricey, so they are out. Is there any significant advantage to platinum or double platinum plugs for our cars? How about the E3 or NGK V electrode types?

Kostas
 
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kkritsilas

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Champions are a lot easier to get up here than Autolites. Even the Wal-Mart stores up here have Champions, only. Some of the auto parts stores have NGK, Bosch, Nippon Denso, or house brand, but the best selection always seems to be the Champions. I don't really have any brand loyalty, so I couldn't find the Champions, I'd take the NGKs or Bosch. I tend to stay away from house or unknown brands, just because I don't have a track record to go on. I was more interesting in knowing if anybody had used the platinum, double platinum, or irridium plugs on our cars, and if so, had any experiences they would consider to be better than the standard copper plugs. I think consensus that this point is that the Champion copper spark plugs are fine to use.

Kostas
 
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Locomotion

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I've used Champion, Autolite and NGK in my street vehicles as well as race car. I also tried Accel silver plugs in the race car. They all seem to work equally well. It's more important to use the correct heat range and keep everything properly tuned. I did notice that Champions seem to rust faster than the other brands. But I noticed that with the used plugs I kept aside for moving the car around at home. I put the old plugs in to keep the fresh ones from loading up.

RN12Y or their equivalent in another brand could work well too. They are a slightly cooler heat range. I believe they were recommended for mid-'70's 340's & 360's. Don't know if it included 318's.

Non resistor N9Y were used in the early, high compression 340's. Then pollution laws mandated that everything run hotter and leaner.
 

alf44

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i use champions rn 14 yc also but have used the NGK plugs with good results. plugs are supposed to be gapped at .035, but i tried the champions at .045 and my 318 runs better. is that strange? anyone else try larger gap?
 

alf44

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was going to regap my super /6 to .045 and see how she purrs.lol
 

tim berry

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i was given a set of e3 plugs ( i normaly run rn12y champions ) the car ran differant with the e3s it idels smooth but seem soft on accelleration. i liked the champions better . i checked the resistance of the two brands ,the e3 has a lower resistance than the champions but i dont know if the heat range has an effect on this . but here is the big differance the champions are made here in the usa plus the cost is a lot better !
good luck
 

Mr.Lopar

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I wanted to try the e3s in my ram when I built the stroker, but couldn't justify the price for something I wasn't sure how theyd work,so I stuck with the champs
 

dankwiz

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As far as I can tell, the only benefit of the high dollar special plugs is their life span. Coppers usually last me about 20k miles and cost a whopping 10 or 12 bucks a set.
 

tim berry

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remember that after 3k rpm their just glo plugs any way so I think heat range my be more important
 

NoCar340

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remember that after 3k rpm their just glo plugs any way so I think heat range my be more important
Say what?! Absolutely not true.

I would probably run the RN12YCs. I wouldn't recommend the platinum Champion equivalents, though. For some reason, the Champion Platinums I've sold seem to have a lot of compression-leakage problems even though they ran fine. You could actually see where the flame travel was going up the ceramic into the plug boot. I've not seen that problem with the standard Copper Plus line. Either way, I've not seen an actual performance increase with platinum plugs anyhow. Plug brand seems to matter less with newer MPFI engines, but the older carbed engines seemed to really like whatever they were born with, brand-wise. ACs in a GM, Autolite/Motorcraft in a Ford, Champions in a Mopar.
 

kkritsilas

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NoCar340:

Its funny you say that about the newere MPFI enginers. My daily driver is a 1996 Dodge Grand Caravan LE. It has the 3.8L Chrysler V6. The manual recommends a particular Champion double Platinum plug. Consensus on some Internet Chrysler Mini-van sites is that these are the ONLY plugs that will allow the van to perform properly. Any other plug, even far more expensive/exotic ones, create drivablility, fuel economy, or a loss of power issues. Everybody who has deviated from the recommended Champion Double Platinum plugs has had one or more of the above problems.

As for me, I will go with the Champion RN14YCs unless I find that there is a need for colder plugs, in which case RN12YCs will be the go to. I will stick with the standard Copper Plus plugs, and change them as per the normal change interval. Cheaper plugs (albeit the recommended ones) changed more often vs. more expensive plugs changed less often; pretty close to a wash in my mind. Besides, changing plugs allows for any internal problems to perhaps be detected, so trade that off for the extra labour in changing the plugs more often.

Kostas

P.S. What is everybody paying for plugs? Rock AUto is showing them at $1.82 CAN each, the local parts stores seem to sell them in pairs at 4.99-6.99/pair.
 
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NoCar340

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Well, it's a most-case scenario, not one size fits all. I've run into similar issues, but they're not common. I wonder if any of the minivan owners ever looked for burning on the ceramic outside the chamber. It seems to be limited to the Champion platinum/double platinum plugs.

If you're really bored sometime, try to find a PCM for a 2004-2005 Ford Escape V6. I had to send one of those PCMs out for reman for a customer because we couldn't find a used one anywhere, and we searched the whole country. They absolutely, positively must have the Motorcraft plug as original or it will blow one or more of the coil drivers. There was a TSB on it, in fact. The Autolites won't work, which is funny since the Motorcraft plugs are actually made by Autolite. That's just being hyper-tweaky on the engineers' parts. The system should be more robust than that.

By the same token, I've sold literally thousands of TR5GP/3186 NGKs for GMs over the years with no ill effects. That might have something to do with the fact that AC-Delco hasn't actually made a single spark plug in about 20 years, but that's another discussion...
 

tim berry

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I stand corrected its 7500 rpm for the glow plug effect some times the brain farts and the wrong info comes out sorry for any inconvenience to anybody ! thanks to nocar 340 for setting this straight.
 

slant6billy

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Lots of good info. My first stroked slant was very erratic and being an odd motor to be heavily worked with the head and cam ( I don't think it was meant to be raced up like that). I had to go to a copper Champion plug with a very hot heat range. Now immediately No 5 was not happy, so I backed it down to the stock call out. Did the same for No2 after it too was heat fouled. I cheated No 3 and No4 with non-foulers ( threaded sewing thimbles with the hole) . I know my 88 GTA need cooler plugs on 3, 4, 5, &6 since the engine bay was a hot box- thus making me hate GM even more for that stupid flawed design. I guess without easter egging different plugs on a V8 to deal with hot cylinders and cooler cylinders, the intake and headers would help with that uneven burn issues. Still, I'll keep a watch on my next build. Any feeling on Iridium plugs? I hear ravs of them on TV, but the truth is difficult when endorsed with $$$. Ideally, a good plug should perform and be emission friendly, but that is not always the case. I had to pull all the triple platnums out of the Ram SS/T and go to copper Champs, but that truck came from mopar performance NOT emission friendly.
 

NoCar340

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Much of the heat range consideration is going to based on your use. I recommended the RN12YCs based on the fact that, well, I tend to run engines at high RPM a lot. My first high-performance Mopar was a 340 Challenger with 4.10 gears and a 4-speed and it spent a lot of time near the big end of the tach. It ran better on RN11YCs, one heat range colder than recommended. I also had better results with the J-series projection, rather than the longer N tip for reasons I won't explore.

I guess the best recommendation I can give you is to go with the plug designed for your cylinder heads as far as thread, tip projection, etc. In most cases for FMJ cars, this is going to be the RNxxYC. If your engine and gearing are stock and your driving habits are of the daily-driver style the factory expected most of these cars to see, then go with the original heat range recommended. I would stand by this recommendation even with the addition of a 4-barrel and free-flowing exhaust if you generally just motor it back and forth to work, Church, the grocery, etc. using the extra power primarily for passing and a once-in-a-while blast down on the freeway or empty side street.

If you've made the above mods and tend to run your car hard regularly, then you'll want to explore a colder heat range--318-4V police-fleet cars ran the RN12YC rather than the 14, because they beat the snot out of the patrol cars regularly and the 12 just plain performs better in that situation. If you tossed that 2.27 rearend and replaced it with 3.21s, you're going to be spending more time at higher RPMs period, so you might want to look into the colder plug, particularly if you've done anything in the camshaft department. Combustion is an extremely complex thing and in all honesty, experimentation is the best way to find the right plug if you don't have extremely high-end computer simulators.

The only time you should consider going up in heat range is if you've got a fouling problem. If that's the case, the spark plugs aren't the issue but they will keep you running on all cylinders a little longer until you can address the actual issue, which is usually fuel or cylinder-sealing related.

The only time you should be concerned with the plugs actual design (N vs. J tip, Y vs. J electrode, etc.) is in the case of using aftermarket heads or having changed the pistons for higher (or lower) compression.

In the case of electrode material, I think way too much thought is put into it. I won't get into all the reasons for that statement, but suffice to say your money is much better spent elsewhere in the ignition system. If the man behind the counter tries to sell you a black plastic distributor cap, kindly tell him no thanks. Get one that's tan, blue, or red and has copper-plated or brass terminals, with a rotor to match. Buy better plug wires such as MSD (their StreetFire line is great for the money) or your more-expensive Accels (Super Stock wires are junk). Route your wires carefully; if any two plug wires have to cross, it should be at a 90-degree angle to conserve spark energy (easily done with zip ties). Upgrade your coil to something with some real firepower such as an MSD, Accel, Pertronix, or Mallory. If you're using a factory-style electronic ignition (non ESA), upgrade to an orange unit, or chrome if you run it hard a lot. If you've converted to GM HEI, absolutely save your pennies and get an MSD module for it as OE and parts-store OE-replacement HEI modules are absolute trash, particularly for high-performance use. If you really want to get wacky, index your spark plugs. Then you're really shooting for max power and efficiency, and you probably have a lot of free time on your hands. :icon_winkle:

One last point of consideration: Platinum, double-platinum, and iridium plugs cannot be easily gapped without trashing the electrode(s). You're pretty-much stuck with the gap as supplied.
 
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