I've been running a Champion RJ14YC in my 440+6 RR (no particular reason.) I read in a forum on a google search that if the plug is black, the heat range is too cold, if white, too hot. Mine are definitely black. Does anyone have a recommendation for a better plug choice? Thanks.

black is (& usually is) from fuel fouling as opposed to too cold of plug & 14's definitely ain't too cold. I'd concentrate on what is going on with the choke/jetting/floats (in other words the carb from head to toe)

I considered that as well as I was typing the post and that may be the case. The plugs aren't caked up but they are on the dark side. I'll see if I can upload a pic. Haven't done that here in about ten years.

My 70 6 pack was fouling plugs black. Went thru the whole fuel/carb thing. Finally decided was an oil issue. Long tale of woe. Finally replaced heads with Eddy Aluminums. Instant cure for poor seal between intake and old heads. Heads had at one time been cut, but not intake to match.

If you give up on a possible fuel issue, consider pulling intake to see if ports are slathered in oil.

Any misfiring?

Have you considered running a heat range or 2 hotter plug. Could be running black because of a very moderate driving style. Take car out and blow it out hard on freeway, how do they look now?

Initial timing and other issues could be causing center carb running in transition zone at idle and at very low speed. Possible too high power valve number.

Possible PCV valve issue.

Are all plus black or only some.

Sxrxrnr, no misfiring, the car runs great. When I drive the car, which isn't very often, I generally blow it out pretty good. The only reason I am even looking at the plugs now is because I am doing some other maintenance, like changing header gaskets and such. Yes, all the plugs are black, some a little more than others.

I am considering running a hotter plug, any recommendations? Is the next hotter plug the RJ18YC???

Pics of both sides. As you can see they've been picking up some heat from the headers.

Way to fat on the part throttle cruise, maybe others issues also. Will it start and idle well when cold? Also will it sit and idle for 2 or more minutes when warmed up in gear and not die? What jets are in the center carb. and have you tried leaning out the mixture screws on the out board carbs? What carb. list numbers are yours?
Last thing is those plugs are way to hot for a stock compression pump gas Magnum 440, is your compressio ratio stock or lower?
You can make six paks run really well, with some effort

No choke, but yes starts and idles good, much better in warmer weather of course. Never dies.

I don't know the jet info at this point and have done no adjusting. Last time it was tuned on was several years ago by a local mechanic.

Yes, compression is in the 9.5 or 10:1 range.

Where do I locate the carb list numbers?

That is a hot plug, stock was a J11, which they don't make anymore, the J12 is the replacement. I run 9s with a Holley double pumper and a big cam that is fat on the transition and on the rich side at part throttle and my plugs are always clean. I'd suspect you are WAY rich (burn your eyes rich) or you have an ignition problem.

I would NOT put an 18 plug in there, I wouldn't even run the 14s TBH. What are you running for ignition system? What is your timing set at?

I had an engine once that would carbon up the plugs like that but ran great. The stock distributor had about 10 thou of play in it, opening and closing the point gap as it wobbled around. Never back fired and ran clean and mean though. Put a new dizzy in it, ran the same but the plugs stayed clean looking.

I probably need to go back to tuning 101, haven't messed with this stuff in years and didn't know much when I did. lol.

YES, it burns my eyes bad and runs me out of the garage when I fire it up in there.

Stock type electronic distributor / chrome box / Timimg unkwown at this time.

I know it's hard for you guys to help me with all the unknowns at this time. Hadn't intended to get into all this, but I guess I need to.

Try turning the idle mixture screws in slowly and GENTLY on the center carb while it is idling until they bottom out GENTLY. If it stays running with both of those screws in all the way you will need to work on the idle screws on the outboard carbs also, they may be hidden and coverd up in the base plate with lead plugs The carb. list numbers are on the back side of the carb main bodys on the passenger side right below the air cleaner base rings Another thing to check is with the motor idling and the air cleaner off is to look down all three carb tops and see if you see any fuel dripping from the boosters that hang into the center of the carb. If so that should be your first thing to correct Let us know what you find

Thanks guys. Bear with me, heading out of town so it will be a bit before I get back to this.

Check timing, and check fuel pressure if you can. What kind of pump are you running?