NGK spark plugs breaking.

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cruiser

cruiser

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Hi All: I seem to have a persistent problem with the plugs in my slant six 1974 Duster. The engine is all original and unmodified. As per recommendations on this forum, I've been running NGK ZFR-5N plugs, washers removed, gapped to .035 and torqued to 30 ftlbs. as per the FSM. I'm generally pretty happy with them, but have had three with broken electrodes lately. Has this happened to you? Any ideas why? Would you recommend a different plug? I'm a bit hesitant to move to another plug, but these keep breaking. Thanks - cruiser

IMG_5051.jpg
 
I'm into small blocks, not /6, but the plug threads as well as the electrode is longer than anything I've seen before. It actually wouldn't surprise me if the pistons are hitting it. If different plugs break, it may depend how the electrode is oriented in the chamber once installed.

I see them listed for /6 Jeep, nothing for Dodge/Plymouth /6.
 
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That is the recommended longer plug, to get the plug closer to the combustion area. Unless you have shaved your cylinder head an exuberant amount, hitting the piston isn't the problem. If you were hitting pistons, you would know it.

My recommendation would be to thoroughly inspect the plug, before the install. And to be careful with the plugs when installing. I use the same plug, and have never had any issues. And my cylinder head is shaved .100
 
are you using a socket with the rubber washer inside that grabs the plug so it won't fall out while removing/installing?

If you are not, it doesn't take much to have the socket misaligned with the plug which causes contact with the metal socket to the ceramic insulator causing it to break.


Spark Plug Failure #1 Socket Strike! | The Spark Plug Manual
 
ch1ll said:
Post a picture of a broken plug.
Click to expand...
I threw them away, so I don't have a photo of the broken plug. The photo above is the same plug, but not cracked. The cracked ones looked exactly like the one in the photo except that they had a crack in the full vertical length of the ceramic insulator.
 
Heywodja said:
are you using a socket with the rubber washer inside that grabs the plug so it won't fall out while removing/installing?

If you are not, it doesn't take much to have the socket misaligned with the plug which causes contact with the metal socket to the ceramic insulator causing it to break.


Spark Plug Failure #1 Socket Strike! | The Spark Plug Manual
Click to expand...
I think you just solved my problem. After reading your post, I went out and inspected my socket set. Sure enough, the foam insulator in my spark plug socket was missing. Somewhere along the line the foam insert fell out and I missed putting it back in. This was about the time I started breaking spark plugs. Will go out and get a correct socket with the foam insert in it. Thanks for a good catch!
 
Locomotion said:
I'm into small blocks, not /6, but the plug threads as well as the electrode is longer than anything I've seen before. It actually wouldn't surprise me if the pistons are hitting it.
Click to expand...

Nope. The thread length of the ZFR5N is identical to that of a Champion N14Y (original plug on pre-'75 Slant-6s and on approximately seventy-three million LA V8s). The electrodes are longer, which is the point of using these plugs—they move the spark away from metal-wall quenchout zones, for more consistent ignition of even marginal mixtures. Of course, they aren't a universal drop-in for any/every engine, because yeah, you do have to make sure the pistons won't smack the electrodes. There's adequate clearance on stock and near-stock 225s and 318s and 2.2/2.5 nonturbos and a fair good whack of other Mopar motors.

Locomotion said:
I see them listed for /6 Jeep, nothing for Dodge/Plymouth /6.
Click to expand...

There aren't any spark plugs listed for /6 Jeeps because there aren't any /6 Jeeps, number one. Number two, constraining yourself to what you think you see in the listings sometimes means you aren't going to get where you want to be.
 
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slantsixdan said:
Nope. The thread length of the ZFR5N is identical to that of a Champion N14Y (original plug on pre-'75 Slant-6s and on approximately seventy-three million LA V8s). The electrodes are longer, which is the point of using these plugs—they move the spark away from metal-wall quenchout zones, for more consistent ignition of even marginal mixtures. Of course, they aren't a universal drop-in for any/every engine, because yeah, you do have to make sure the pistons won't smack the electrodes. There's adequate clearance on stock and near-stock 225s and 318s and 2.2/2.5 nonturbos and a fair good whack of other Mopar motors.



There aren't any spark plugs listed for /6 Jeeps because there aren't any /6 Jeeps, number one. Number two, constraining yourself to what you think you see in the listings sometimes mean you aren't going to get where you want to be.
Click to expand...
Technically, the thread length is longer without the washer!
Are you getting me on a technicality that a Jeep 4.0/242 is not a /6 but a L6? I guess I should have generalized & just said "inline" 6.
I'm familiar with the benefits of a central ignition point. Plug design and problem was interesting and I just offered a potential possibility. Obviously I was wrong in my guess for that particular application and not too proud to admit I learned a little bit.
But I didn't realize some people were so 'touchy" in this group. I must have leaned over the fence a bit too much.
 
slantsixdan said:
Nope. The thread length of the ZFR5N is identical to that of a Champion N14Y (original plug on pre-'75 Slant-6s and on approximately seventy-three million LA V8s). The electrodes are longer, which is the point of using these plugs—they move the spark away from metal-wall quenchout zones, for more consistent ignition of even marginal mixtures. Of course, they aren't a universal drop-in for any/every engine, because yeah, you do have to make sure the pistons won't smack the electrodes. There's adequate clearance on stock and near-stock 225s and 318s and 2.2/2.5 nonturbos and a fair good whack of other Mopar motors.



There aren't any spark plugs listed for /6 Jeeps because there aren't any /6 Jeeps, number one. Number two, constraining yourself to what you think you see in the listings sometimes mean you aren't going to get where you want to be.
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Thanks, Dan. I know you recommend going with the NGK ZFR5N plugs for my stock 1974 slant, but if you did go to a Champion plug, which one would you use? I don't think Champion makes the N14Y any more. Thanks!
 
Something is up.
I have not once ever pulled a broken NGK out that didn’t get hit.
Especially 3, and I don’t think it is the plug socket either.
Not unless they are literally getting thrown down the hole. :D
 
I'll throw this out there for what it's worth. I believe the 30 LBFT is for the plugs with washers, so the washer gets crushed. Once you remove the washer, I don't believe I'd go down 30. I've never in my life torqued a plug down and never had issues.
 
RustyRatRod said:
I'll throw this out there for what it's worth. I believe the 30 LBFT is for the plugs with washers, so the washer gets crushed. Once you remove the washer, I don't believe I'd go down 30. I've never in my life torqued a plug down and never had issues.
Click to expand...

OH GOOD LORD!!!
You probably don’t torque wheel bearing nuts either.

JK
 
TrailBeast said:
OH GOOD LORD!!!
You probably don’t torque wheel bearing nuts either.

JK
Click to expand...
Now all of a sudden we need to torque the bearing nuts? Next you’ll probably tell everyone that you have to you a left handed metric crescent wrench on the brake bleeders..

:rofl:
 
cruiser said:
if you did go to a Champion plug, which one would you use?
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None; I don't reward companies for putting out poor-quality junk by buying it. There's no good reason to cut fingers (and booger up head threads) with those sharp-edged, shoddily-cut threads of theirs, nor put up with a spark plug that's almost kinda near sorta the right heat range on account of their massive overconsolidation, when you can buy much better-made NGKs of the right heat range for reasonable money.
 
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Locomotion said:
Technically, the thread length is longer without the washer!
Click to expand...

No, the thread length is the same whether or not the washer is present.

Locomotion said:
Are you getting me on a technicality that a Jeep 4.0/242 is not a /6 but a L6?
Click to expand...

Looks like it, a little around the edges, if you stand in the right spot and kinda squint.

Locomotion said:
I didn't realize some people were so 'touchy"
Click to expand...

I'll have to beg your pardon for seeming snappish. Comes of having explained about these spark plugs endless times over many years on here. I guess I should put that on the other side of the "I'm retired" wall and not mention it again.
 
cruiser said:
I think you just solved my problem. After reading your post, I went out and inspected my socket set. Sure enough, the foam insulator in my spark plug socket was missing. Somewhere along the line the foam insert fell out and I missed putting it back in. This was about the time I started breaking spark plugs. Will go out and get a correct socket with the foam insert in it.
Click to expand...

Ah tellya whut, I got tired of foam and rubber inserts breaking/getting sticky/swelling/otherwise making a nuisance of themselves, and bought a plug socket with a magnetic insert instead. Ahhhhhhhhhh. Much better.
 
Two different stories:
- electrodes breaking off [ post #1 ]
- post #6, it is cracked ceramic.
- is it both?
 
slantsixdan said:
Ah tellya whut, I got tired of foam and rubber inserts breaking/getting sticky/swelling/otherwise making a nuisance of themselves, and bought a plug socket with a magnetic insert instead. Ahhhhhhhhhh. Much better.
Click to expand...
I have also used a piece of rubber hose that pushes firmly over the porcelain end and spun them in that way. New hemi's have long tubes too, and it's helpful.
 
I hate to agree but the Champion plugs have been slipping for a time now. They were my favorite plug at one time. Now I use either Autolite or NGK.
 
Charrlie_S said:
I haven't used a Champion spark plug in over 30 years. Junk then, junk now. Agree on autolite or NGK
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I can't say that. I've had good service from them up until I got one that was made "bent" about three years ago.
 
I wonder how the E3 Plugs work. I want to try them. I have Auto lites and the NGK's in my cars right now. I remember trying Splitfires when I was a kid and they worked well, but everyone said they were a gimmick
 
TF360 said:
I wonder how the E3 Plugs work. I want to try them. I have Auto lites and the NGK's in my cars right now. I remember trying Splitfires when I was a kid and they worked well, but everyone said they were a gimmick
Click to expand...
I've never tried them in something without a computer, BUT I can tell you this from direct experience. I tried them in my 08 Jeep Wrangler and they made it run like it had terrible torque converter shudder. Felt like the truck was goin over a really ROUGH washboard. Put the factory Champions back in and all was well. I never wouldda believed it. I've read similar stories too. I've not seen very many people talk good about them.
 
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