What is the best spark plug for carbon fouling?

[Northcoast300h]

I have 1 cylinder in my 1970 440 that carbon fouls, almost positive its a valve issue. All other plugs still look great. (Bosch Platinums). Engine has 154,000 miles and car was abused before I bought it 20yrs ago. Per pic, I know I waited too long to check spark plugs. Carbon fouling to point of misfire usually takes 10yrs (I only put 700 miles per yr, so 7000 miles). Always misses a little when first started but all 8 fire after a couple minutes. I'm lazy and cheap so I've tried additives to clean the valves. It worked a little but still carbon fouls. Since I'm lazy/cheap, I'm not going to do a valve job and would like to know what spark plug to buy.

From what I've read, I need to buy a hot plug with the same length or a plug engineered for carbon fouling. I think a NGK XR5IX (for 440 - part#NGK 7355) would work or am I reading the attached cross ref incorrectly (5 is a hot plug) I have a headache now from the hours of looking at spark plugs online, so would like to hear from others.

Will there be any problem with running 1 hot NGK and the remainder the old Boschs?


Thanks

 

[bronze turbine]

I don't think you need a valve job, maybe just a valve seal. Anyway, if you were to put a different plug in one cylinder, as long as it was firing I don't think you'd notice any difference at all.

 

[commando1]

From what I've read, I need

to realize that a different sparkplug is not a fix for your fouling. You need to read up on all the reasons why just one cylinder out of 8 can keep fouling.
My money is on the valve guide or piston ring.

 

[CBODY67]

Look at the heat range cross to Champions. J-12Y or even J-14Y were normal heat ranges, back then, for Chrysler 383s and 440s. The NGK you have chosen is a notch COLDER than the J-14Y cross.

From the magnitude of what I see, I don't see how that could be just "a seal" on that one cylinder, but it's probably a failed oil scraper ring instead.

There are "non-foulers" you can buy for spark plugs. They are basically a bushing you put into the spark plug hole, then screw the spark plug into it. It puts the plug in more of a protected place (out of the main air/fuel mixture area so any oil will not get directly on it. Therefore, it is less prone to fouling from oil and such . . . allegedly. That, plus making sure the affected plug wire is in good condition, too.

IF that plug is gas-fouling, you should be smelling gas in the motor oil, as in smelling what's on the dipstick. NOT good. Clean that plug up and get a non-fouler for it.

Just some thoughts,
CBODY67

 

[Blusmbl]

x2 on the anti fouler. Just going up a heat range on the plug is not going to cut it, and a -5 NGK is the stock heat range, you'd need to go to a -4 at a minimum, but with all of the oil on that plug it isn't going to resolve it. The anti-fouler worked for me on a Pontiac 400 I had. The oil is reducing the octane but as long as you drive it gingerly it should help get you by until you decide to fix either the valve guide or rings in the one cylinder with oil control issues.

 

[Justin Plant]

Please understand that changing the heat range has nothing to do with the length or reach of the plug. The heat range is determined by how far the ceramic reaches into the plug case before it touches. The hotter the plug the further into the case the ceramic goes. Most Auto part stores look ups favor the hotter part numbers already, If, by some miracle they still have an NGK book on hand, the guide used to be in the first few pages. Ask for the book and study it. Then look for the numbers you may need. Don't be surprised if what you want isn't on the shelf. The length of the plug does not change with the design family of that plug. You'll have to change plug family. It's been a long time, I used to be able to recite all definitions of each initial in an NGK part number. And all other brands for that matter. I can tell you that changing the reach can be quite dangerous for obvious reasons. The heat range however, should prolong the "foul out" of the plug. At least a little. I agree with a non- fouler. There's one in my Dodge too.

 

[rags]

I know I waited too long to check spark plugs.

gee, do you think so? that plug started misfiring long before it got to that condition. maybe it broke a ring on the last trip before that plug was pulled.

 

[Welder guy]

NGK XR5 V-POWER is what you need . They resist fouling to a high degree. I been using them in my 383 and I’m very happy with them . A few of my mopar friends started using them in their 383’s with great results. We all switched over from champion J-12Y. Good luck

 

[Mudeblue]

I have 1 cylinder in my 1970 440 that carbon fouls, almost positive its a valve issue. All other plugs still look great. (Bosch Platinums). Engine has 154,000 miles and car was abused before I bought it 20yrs ago. Per pic, I know I waited too long to check spark plugs. Carbon fouling to point of misfire usually takes 10yrs (I only put 700 miles per yr, so 7000 miles). Always misses a little when first started but all 8 fire after a couple minutes. I'm lazy and cheap so I've tried additives to clean the valves. It worked a little but still carbon fouls. Since I'm lazy/cheap, I'm not going to do a valve job and would like to know what spark plug to buy.

From what I've read, I need to buy a hot plug with the same length or a plug engineered for carbon fouling. I think a NGK XR5IX (for 440 - part#NGK 7355) would work or am I reading the attached cross ref incorrectly (5 is a hot plug) I have a headache now from the hours of looking at spark plugs online, so would like to hear from others.

Will there be any problem with running 1 hot NGK and the remainder the old Boschs?


Thanks
View attachment 601657
View attachment 601661

View attachment 601662

Looks like a

I have 1 cylinder in my 1970 440 that carbon fouls, almost positive its a valve issue. All other plugs still look great. (Bosch Platinums). Engine has 154,000 miles and car was abused before I bought it 20yrs ago. Per pic, I know I waited too long to check spark plugs. Carbon fouling to point of misfire usually takes 10yrs (I only put 700 miles per yr, so 7000 miles). Always misses a little when first started but all 8 fire after a couple minutes. I'm lazy and cheap so I've tried additives to clean the valves. It worked a little but still carbon fouls. Since I'm lazy/cheap, I'm not going to do a valve job and would like to know what spark plug to buy.

From what I've read, I need to buy a hot plug with the same length or a plug engineered for carbon fouling. I think a NGK XR5IX (for 440 - part#NGK 7355) would work or am I reading the attached cross ref incorrectly (5 is a hot plug) I have a headache now from the hours of looking at spark plugs online, so would like to hear from others.

Will there be any problem with running 1 hot NGK and the remainder the old Boschs?


Thanks
View attachment 601657
View attachment 601661

View attachment 601662

Looks like an oil-fouled plug caused by oil getting into the cylinder via bad rings or valve guides that are worn! That is one nasty plug!

 

[Northcoast300h]

Thanks for the replies. I'm going to try the XR5's in an oil fouler and see if it helps. I never had luck finding anyone honest to fix my cars. I always got screwed out of thousands, so I just try to fix them myself and run them until they blow up.

For 20yrs, I've changed the oil every 1000 miles (every year and a half). The oil pan was crushed from someone probably jumping the car before I got it, so only 4 quarts fits (see pic). I don't think the crushed part is interfering with the oil pump since I added an oil gauge and pressure is healthy....but who knows? Oil is usually black and smells like carbon, so yeah rings are probably bad in that cylinder, but I never noticed a gas smell. When I punch it, most of the time its a thin grey color, however if I go weeks without engaging the secondaries, then there is a good sized grey cloud that forms behind me. It makes me smile when someone is tailgating me.

When I first got it from the junk yard 20 yrs ago, they said it hasn't started in 10yrs sitting out in a field and needed a new engine. I replaced the rotted fuel tank and lines and got it going and engine starts and runs good since then. I consider myself lucky to drive it for 20yrs with the same old engine and only once broke down on me..(original coil fried). I've upgraded to electronic ignition and thermoquad carb which helped with MPG, starting, smooth idle.

Thanks for your help. You guys are great.

 

[fury fan]

I've had good luck with Autolite 86, which is 1 heat range hotter (85 is 'normal').

You could also have a leaking intake/valley pan gasket, and the offending cylinder is sucking oil in.
I've never experienced that, but a buddy has.

 

[Northcoast300h]

I just read that running a hotter plug will increase the chances of detonating, so I guess I'll just try the oil fouler with a new plug (same heat range as what I got in there).

 

[fury fan]

I doubt going 1 range hotter would cause detonation. I've never noticed it in my cars.
But, oil in a combustion charge reportedly can cause detonation, so there's that. YMMV from mine.

 

[Blusmbl]

It’s going to be at risk of detonation anyway with all the oil in that cylinder- the oil drastically reduces the octane of the fuel.

I run -6’s in my motor for street driving and -8’s when on nitrous. A -5 or -4 in that single cylinder isn’t going to be detrimental as long as you aren’t going to full throttle.

 

[Northcoast300h]

It’s going to be at risk of detonation anyway with all the oil in that cylinder- the oil drastically reduces the octane of the fuel.

I run -6’s in my motor for street driving and -8’s when on nitrous. A -5 or -4 in that single cylinder isn’t going to be detrimental as long as you aren’t going to full throttle.

Its probably the reason why I have to run at least 92. Oh well, I don't know any honest rebuilders so I'll just drive it until it stops. I've been screwed too many times for large preventative maintenance I can't do. (like when a trans shop charged me $1000 to replace the bearings in my rear end to stop noise). All they did was put graphite shavings inside. Kept it silent for a few months. After proving it to them, they said "Well, then sue us". Courts cost too much. Thanks for the info.

 

[Northcoast300h]

So after 11 months (about 700 miles) and car sitting for a day, I pulled the Number 6 spark plug (which is located 3rd back on the passenger side, correct)? Last year, I cleaned spark plug. Today, spark plug was wet, oil on threads, some carbon started to form. (see pic). Other spark plugs look good.

I've learned and surprised that Bosch Platinums heat range is 8-9 (which is NGK 4-5). A hot plug. Kind of high for a 440, but I'm running electronic ignition, low ohm coil, and from what I've read, engineers say to go as hot as possible without experiencing detonation for less fouling, best performance and life. Is that correct? I noticed I have to use at least 92 octane....but don't all 440's have to use 91?

Wondering if there's any oil additives? I'm using 1/2 bottle STP oil treatment and change oil every year with high mileage 10W40. Car seems to run pretty clean after its warmed up. Anyhow, I'm going to try one of those anti foulers and a new Bosch. I guess I'll post in 2025 to tell you if it worked.

Thanks to all who replied to my issue.

 

[CBODY67]

You probably need to get a borescope attachment (or a "critter cam" from Harbor Freight) and look at the piston crown on #6. If the edges of the piston are clean, that is an indication that oil is "coming up from the bottom", as in failed oil ring package. If not washed clean around the edge, that means oil is coming in from the top side (as in worn valve guide and failed valve stem seal). Might even be a combination of both!

2bbl motors used Champion J-14Y (383) and J-13Y (400). 4bbl motors could go as cold as J-10Y, but could also be as warm as J-12Y closer to 1972 or so. Always use an extended gap plug, no matter the brand! Which is what the "Y" designates in Champion plugs. Seems like the NGK -5 heat range works well in my Chrysler 383s, too.

The addition of the STP viscosity improver additive moves the oil more toward a 20W-50, so less expensive to just put 20W-50 in it to start with. I used Castrol GTX 20W-50 for many years in my cars. But they had no oil use issues out of the ordinary.

Might put some Gumout or Techron fuel additive (with the desired PEA additive in them) in the gas tank and go on a two hour road trip to help clean things out. Then look at the spark plugs. All should have beige or whiter ceramic insulators, but not chalky white (which means "too lean").

The role of the "anti-fouler" is to get the plug out of the normal "path" of the oil, but as it also gives the plug insulator less cooling air, it can make a normal plug effectively run hotter. Only a stop-gap method at best!

Just some thoughts and observations,
CBODY67

 

[Northcoast300h]

You probably need to get a borescope attachment (or a "critter cam" from Harbor Freight) and look at the piston crown on #6. If the edges of the piston are clean, that is an indication that oil is "coming up from the bottom", as in failed oil ring package. If not washed clean around the edge, that means oil is coming in from the top side (as in worn valve guide and failed valve stem seal). Might even be a combination of both!

2bbl motors used Champion J-14Y (383) and J-13Y (400). 4bbl motors could go as cold as J-10Y, but could also be as warm as J-12Y closer to 1972 or so. Always use an extended gap plug, no matter the brand! Which is what the "Y" designates in Champion plugs. Seems like the NGK -5 heat range works well in my Chrysler 383s, too.

The addition of the STP viscosity improver additive moves the oil more toward a 20W-50, so less expensive to just put 20W-50 in it to start with. I used Castrol GTX 20W-50 for many years in my cars. But they had no oil use issues out of the ordinary.

Might put some Gumout or Techron fuel additive (with the desired PEA additive in them) in the gas tank and go on a two hour road trip to help clean things out. Then look at the spark plugs. All should have beige or whiter ceramic insulators, but not chalky white (which means "too lean").

The role of the "anti-fouler" is to get the plug out of the normal "path" of the oil, but as it also gives the plug insulator less cooling air, it can make a normal plug effectively run hotter. Only a stop-gap method at best!

Just some thoughts and observations,
CBODY67

Cool, I bought a cheap borescope years ago. I can finally use it. I've always had a valve tick in number 6 or 8. For the first year I had the car, I put fuel additive that cleans that cleans the valves in every fill up. The valve tick noise slowly became better, but never went away. I guess I'll start throwing additives in it again. I'll use the borescope this week. Thanks for the info. I can't find Bosch's WR9FP's sold as singles, so I'm going with one NGK XR5IX Iridium.

 

[fury fan]

Did you see my post#11 on the leaking valley pan?
It can allow oil to be sucked into a cylinder, and I believe does not cause a vacuum leak, either.

 

[Northcoast300h]

Did you see my post#11 on the leaking valley pan?
It can allow oil to be sucked into a cylinder, and I believe does not cause a vacuum leak, either.

I saw it, but then forgot about it, sorry. Thanks for posting. How do I find if my valley pan is leaking?