Oh No ...., Another Spark Plug Question

[72DL41]

Basics: '72 Polara base model; 21k miles (orig.); 360/auto. (orig.); electronic ignition and orange plug wires (orig.); used for cruise nights and car shows; currently in winter storage.

- Currently has Champion RN14YC plugs
- My reproduction '72 FSM calls for N13Y plugs
- My reproduction '72 Operators Manual calls for N10Y or 62P

Could the FSM or O/M be a misprint? Could Dodge have determined that any or all of the plugs mentioned above would suffice for the average driver?

Come springtime, I plan to install NGK V-Power plugs. I was very satisfied with their performance in a 440 engine I had previously. The NGK heat range cross reference chart shows up to a two-point hotter range; N10 = NGK 6; N14 = NGK 4. Based on how I use the vehicle, is this a concern regarding which NGK plugs to get? I assume I could split the difference and get NGK 5, which equals Champion 11, 12.

Thanks for all the previous help/support. Happy New Year!

 

[Xcudame]

"R" means resistor and other than the built in resistance there's no difference. I prefer to use a Champion "12" heat range for big and small blocks for a cruiser. So I'd pick the NGK 5 plugs.

By the way, back in the day my brother and I used the take a tiny triangle file a cut a v groove in our Champion plugs thinking it gave us a better chance of a spark. Truth be told, there was no performance gain. We sure wasted time when we were going and dumb and didn't know better.

 

[CBODY67]

Back in the later 1960s, I would spend hours on a Sunday afternoon filing down the ground electrode to get to a "Champion J-gap plug" equivalent. Where the ground electrode only covered 1/2 of the center electrode, for a better spark response. I could tell a bit of a difference, to the good. So that became my modus operandi for decades, until I discovered the NGK V-Power plugs. Same thing, already done! As to the ground electrode only covering 1/2 of the center electrode.

The first set went into my '80 Newport 360 2bbl. The Autolites in it were not doing anything other than normal, but as soon as it started with the V-Power plugs, I could tell it liked them. In other engines, with more of a closed chamber, not so much difference, but still worked better. Seemed that the engines with "lazy air" showed more improvement, but engines with "active air" showed less improvement. But still allowed me to lean-out the choke settings a bit.

As mentioned, the "R" is for resistor plugs. NO performance difference, just quieter radio sound with much less possible static. The "C" is for "copper core". More of a marketing issue to me, fwiw.

I concur on the comments about the heat range. A "12" seems to work for most of the LA and B motors we've had over the years. The "10" heat range was usually reserved for the 4bbl motors, as those were generally for law enforcement vehicles which could spend a good while at WOT in pursuits, so a colder plug. "13" and "14" plugs were usually in the lower perf 2bbl engines. So the RN12YC Champions will be fine, if you use Champion plugs.

By the way, NGK heat range numbers run opposite of other brands! In the NGKs, higher numbers mean COLDER, not hotter as the others do.

Happy New Year!
CBODY67

 

[Gerald Morris]

Back in the later 1960s, I would spend hours on a Sunday afternoon filing down the ground electrode to get to a "Champion J-gap plug" equivalent. Where the ground electrode only covered 1/2 of the center electrode, for a better spark response. I could tell a bit of a difference, to the good. So that became my modus operandi for decades, until I discovered the NGK V-Power plugs. Same thing, already done! As to the ground electrode only covering 1/2 of the center electrode.

The first set went into my '80 Newport 360 2bbl. The Autolites in it were not doing anything other than normal, but as soon as it started with the V-Power plugs, I could tell it liked them. In other engines, with more of a closed chamber, not so much difference, but still worked better. Seemed that the engines with "lazy air" showed more improvement, but engines with "active air" showed less improvement. But still allowed me to lean-out the choke settings a bit.

As mentioned, the "R" is for resistor plugs. NO performance difference, just quieter radio sound with much less possible static. The "C" is for "copper core". More of a marketing issue to me, fwiw.

I concur on the comments about the heat range. A "12" seems to work for most of the LA and B motors we've had over the years. The "10" heat range was usually reserved for the 4bbl motors, as those were generally for law enforcement vehicles which could spend a good while at WOT in pursuits, so a colder plug. "13" and "14" plugs were usually in the lower perf 2bbl engines. So the RN12YC Champions will be fine, if you use Champion plugs.

By the way, NGK heat range numbers run opposite of other brands! In the NGKs, higher numbers mean COLDER, not hotter as the others do.

Happy New Year!
CBODY67

When I run out of my horde of old plugs around 2045, I'll try NGKs. Japanese electrical wares and work excel all others as a rule. I might shake loose some boxes of Champion J14Ys if I don't get any more 2bbl motors to run.

 

[bronze turbine]

N14Y or equivalent. This is what our '76 Newport used. 360-2bb.

 

[lemondana]

The early 360's called for N13Y's.

 

[CBODY67]

As a point of reference, when I got my '70 Monaco 383 4bbl, the spec was J10Y, which I knew was a "cold" plug, although some lower numbers were cataloged.

I knew our 383 2bbls all had J14Ys in them. They all burned with the correct ceramic coloring. The '72 Newport 400 2bbl was J13Ys. They all burned with the correct ceramic color, too.

What I have determined is that the "police motor" engines used the much colder plug to help prevent WOT detonation as many municipalities used regular fuel rather than buy the more expensive premium fuels. When driven normally or idling around, no issues. As the extended gap plugs would keep the end of the plug hotter, but when needed at WOT and higher engine speeds, the extended tip would keep the plug cooler. Aided by the cooler heat range to start with, plus the less total advance (usually abt 31* BTDC, compared to the 2bbl's 36* BTDC, on a 383), even less possibility of detonation at WOT.

On our '66 Newport 383 2bbl, I usually ran it at 15*BTDC initial, compared to the spec 12.5* BTDC. Ceramics burned the same color, so it was not too much advance or too lean.

So to me, the "12" heat range (in Champions) is a good general-use heat range, whether in a LA or B/RB motor. Just my experiences.

My general rule of thumb is to start with the OEM heat ranges, then you can move down a notch and put a few more degrees of initial advance into things without causing issues, once the baseline is set.

A few years ago, I found an article on how heat range could affect vehicle emissions. Going one notch away from OEM spec could increase emissions, it demonstrated with numbers. So if an engine suddenly got different heat range spark plugs when it was "emissions controlled", that was possibly why. Things that would not show up in normal use, but would show up on instrumented testing. FWIW

In earlier times, I would keep the better (as to gap wear) Champions in a stash of used plugs. All J14Ys from our '66 Newport 383 2bbl. I discovered they worked just fine in our Briggs-Stratton lawn mower engine! Had to stretch out the plug wire from the shroud, but I could get them to fit. Ran fine! LOL That's where I prototyped my "bent ground electrode" theory out, versus the original J-gapped plug. Seemed to work just as well, without the filing time on the electrode end.

Just my experiences and observations,
CBODY67

 

[wyrmrider]

In a small block with lower compression use the AMC developed extra long extended tip Champion number with a YL come in 5/8 and 13/16 lots of part numbers
The start quicker, miss less, stay clean the long tip is cooled by gas
spend some time in a catalog and look them up

 

[CBODY67]

In a small block with lower compression use the AMC developed extra long extended tip Champion number with a YL come in 5/8 and 13/16 lots of part numbers
The start quicker, miss less, stay clean the long tip is cooled by gas
spend some time in a catalog and look them up

The OTHER thing to consider is any possible interference with piston tops. Which is not good!

Agreed, with a '72-era 40 where the piston is .125" "in the hole" at TDC, no issues, most likely. But a 1969 10.0CR motor, with basically "zero deck", the extra electrode length might be an issue. CHECK FIRST!! "Extended gap" "Y" Champions (or equivalent) only.

Some brands of extended gap plugs extend less into the cyl than others, by observation.

Just some thoughts,
CBODY67

 

[Retired auto tech]

As an auto-electric tune-up shop in the 70s and 80s we made it a practice to replace plugs with what came in the vehicle from the factory. We adjusted heat range and tip depending on what the plug color, fouling and useage of the vehicle. However this required us to keep a very large inventory plugs on hand. When the NGK V-Groove was introduced, the sales rep made some very what seemed extravagent claims for it.

I had him send me a set for my dailey driver wich was a 1986 Bronco II with the 2.9l EFI and five speed tranny. I first put in a brand new set of Motorcraft plugs and put it on the analyzer recording required voltage, spark duration and condition and tail pipe emmisions. I then drove for a week and repeated the tests.

I then installed the NGKs and repeated the tests. What I found was that the required voltage to ionize the plug gap was lowered resulting in a longer spark duration and smoother spark line. This also resulted in reduced cranking time and lowered tail pipe emissions. Ok at this point I am starting to be impressed by some of the claims.

The other advantage to the NGK was the porcelain design as one heat range plug would cover both one higher and one lower than other brands. This allowed us to reduce our stock significantly. Whatever thier process is they now supply some 75% of porcelain in the world used in spark plugs and O2 sensors around the world. As well you will find the NGK iridium spark plugs as the factory installed plug in many makes of today's vehicles. I use the iridium plugs because of thier extended life of up to 200,000 kilometers as changing spark plugs is no longer a part of the fun things I like to do on my car's but because of the cost I probably will install V-Groove in the 440 for the 67 Newport Convert when I rebuild it in the spring.

 

[Gerald Morris]

The OTHER thing to consider is any possible interference with piston tops. Which is not good!

Agreed, with a '72-era 40 where the piston is .125" "in the hole" at TDC, no issues, most likely. But a 1969 10.0CR motor, with basically "zero deck", the extra electrode length might be an issue. CHECK FIRST!! "Extended gap" "Y" Champions (or equivalent) only.

Some brands of extended gap plugs extend less into the cyl than others, by observation.

Just some thoughts,
CBODY67

THANK YOU for this admonition. My 383 was rebuilt with .040 over flat top pistons which come right up to the deck also, as can be seen in the pics I uploaded a bit over 2 yrs ago when we hired that halfwit* to replace the heads. The 915 heads we had refurbished have done as nicely as we expected, and I always am interested in methods of increasing the spark, but will now very likely stick with gapping my BundesBosch platinum plugs out to .040" for the slightly longer spark.

*wife wanted me to do this in case I needed to resort to corrective measures. I won't do so again, given the perfect, invincible ignorance of that and other Modern Chebbie Only goobers to be found in this burg. We KNOW ONE exception, and he stays booked up months in advance as a consequence of his competence.