Champion Truck 4412 plugs are longer than stock...

First post here...

I just bought my first XJ, an '88 Loredo in excellent original condition. Why didn't I get one of these sooner? I've already found tons of useful info in this forum and have spent the weekend running back and forth between the garage and the computer

Anyway, doing the new used vehicle routine. Going over it with a fine tooth comb, changing fluids, tune-up, etc.

I see that 4.0 owners of all kinds, not just XJ's, are fond of the 4412 spark plug. So naturally I bought some. The first thing I noticed is that the 4412 is much longer than the RC9YC oem's in my '88. I found an application guide and it calls for 4430, not 4412, but I see no reference to 4430 on the various Jeep forums.

I don't like the thought of pistons banging into spark plugs so I want to make sure that someone else has installed the 4412 spark plug into a Non-HO head.

thanks in advance...

Hold the plugs up side by side, match the seat (where the washer sits), if the electrode is noticeably longer. IMO, you got to ask yourself if I really want to do this. Longer (hotter) plugs have a tendency to scorch pistons at high speeds and/or sustained high RPM's. See a lot of that over here, there are no speed limits on the interstate (autobahn).
They even recommend (from the dealer) a colder plug for high speed driving here.
I've never had any bad luck, with the owners manual recommended plug. The stock ignition system, isn't one of the weak pints of the 4.0. Anytime I've experimented with other plugs, there was no noticeable difference or they performed worse. I know the stock Champs work well.
One thing I did do that seemed to help (with starts and an occasional cold motor idle miss), was put a set of 8 mm solid core plug wires in, except the coil to cap wire (I kept the resistor wire there, distributor caps are finicky anyway). I was constantly having issues with my plug wires. For what I spent trying to find a good set, I could have bought a set of OEM. Schools still out, on the long term affects of solid core plug wires, they've only been in a few months.

It turns out that the 4430 is the correct plug for the 1988. I guess there just aren't as many compared to the later years combined. Search for 4412 and get a lot of hits. Search for 4430 and get very little. Anyway, they discontinued the 4430, go figure.

One thing I did do that seemed to help (with starts and an occasional cold motor idle miss), was put a set of 8 mm solid core plug wires in, except the coil to cap wire (I kept the resistor wire there),..... Schools still out, on the long term affects of solid core plug wires, they've only been in a few months.

Click to expand...

8Mud, your wire solution is interesting, because that's exactly what I did to my 89, several years ago. I installed a set of solid cores, and had a terrible miss afterward. I mean TERRIBLE. I could barely get it home after a test drive. After re-installing the resistor coil wire only, it ran perfectly. It seems that the solid cores created what's called electrical 'flyback' or feedback to the coil/ignition module. The resistor coil wire created just enough resistance to soak up the electrical spikes and prevent this.

I drove it many years with that setup, and never changed the plug wires. I checked the coil wire resistance from time to time, but it stayed the same. The plugs were always a light gray, with no carbon buildup. No problems with this setup at all.....

ROE

My experience is that the $.89 Champions work the best. I have tried a half dozen other brands and configurations. None seem any better and many seem to drop the power. The multi-electrode Bosch platinums were a real bust. I thought I had a serious problem until I changed the plugs. I run the spiral wound Accell 8mm performance wires. The are a copper conductor but wound in a spiral manner to reduce interference. They read zero ohms but still keep the interference down, unlike the old Packard 440 wires. I never get the straight kit. I get the kit where you put the ends on yourself. The off the shelf kits ALWAYS make the wires longer and you end up with wire everywhere. I make them the best possible length and add spacer bars to keep them from touching each other and the block.

Runnin'OnEmpty said:

8Mud, your wire solution is interesting, because that's exactly what I did to my 89, several years ago. I installed a set of solid cores, and had a terrible miss afterward. I mean TERRIBLE. I could barely get it home after a test drive. After re-installing the resistor coil wire only, it ran perfectly. It seems that the solid cores created what's called electrical 'flyback' or feedback to the coil/ignition module. The resistor coil wire created just enough resistance to soak up the electrical spikes and prevent this.

I drove it many years with that setup, and never changed the plug wires. I checked the coil wire resistance from time to time, but it stayed the same. The plugs were always a light gray, with no carbon buildup. No problems with this setup at all.....

ROE

Click to expand...

When I kept the resistor wire between the coil and cap, I was thinking mostly of cross fire in the cap (from splash), but did consider what I call rebound, or what you called feedback. The set up I have now seems to work well, they are Blue Max 8 mm solid core wires (actually multi core), with a stock OEM coil to cap wire. It's probably just luck, but I'm getting no noticeable interference with my radios. I was getting a lot of high voltage line leak (often heard on the radios) , which I often found the hard way (from finger tip to crotch on the fender). Which would mess with my idle and didn't seem to want to go away, with any of the cable sets I tried. Like Old Man mentioned, the Bosch multi electrode plugs I tried were a bust in my Renix.

Does Champion make a Truck 4412 plug still? I went to get some and all they had were the 412. No truck designation or the extra 4 up front in the number. I am assuming this is the correct plug, they must have just changed the name. When I compared the gap to my old last set of Bosch Plat. they had a different gap. I haven't switched plugs yet and will verify the gap before I install. I was just wondering if anyone else had bought the plugs recently?

Thanks

just bought Champion Truck 4412 plugs at AutoZone. Although they had to order them. I was using Bosch Plat 4's in there, and after reading some post a while back, i figured I'd change them. Many people were complaing about the Bosch's so I wanted to see what the fuss was about. Seems to run smoother.

No one answered the original question of this thread. I too just bought a set of Champion 4412's for my 91 MJ, pulled the original plugs (Champion RC9YC) and the 4412's were a good 3/8" longer than the RC9YC's after the seat. No way I was going to install these things. Does anyone run them in their HO 4.0 engines? Can not see how the 4412's can be a recommended replacement.