Four prong spark plugs

elboberino · August 27, 2003

So I saw the 4 pronged spark plugs at the local auto parts store the other day and was wondering what the benefits of having more than one prong on your plug is. I was also wondering how the heck you can get the gap right one something that is so crowded? Anyone know if it is worth the extra cost of plugs or would I just be wasting money? Thanks in advance!

bigtruck21 · August 27, 2003

I believe they come pre-gapped, but yeah, i don't believe you would be able to adjust them after so many miles if they were slightly off. Supposedly they provide more spark and I tried them way back when, but didn't feel anything extra ordinary other than they being new compared to the old ones. Many other people say the same thing. I've read a study that said on a stock ignition that is usually slightly underpower, you will get the best performance from the tiny electrode iridium plugs like densoiridium and ngk. I put them in the bike and can agree with the smooth operation and more power from the harley plugs. Best performance was obtained on the dyno with aftermarket high output ignition with overgapped standard copper plugs (but wears much faster)

Bish · August 27, 2003

Junk in my opinion. Electricity will follow the path of least resistance so there is only one place it will spark. I have had frients put them in and quickly pull them due to truck running worse.

I stuck with NGK TR-55 regular copper. I replace them every 30K. I just think plain copper gives the best performance. All the platinum and iridium do is add longevity. Plus, I had one of the platinum discs disappear on one of my oem plugs. Don't want to knwo where that ended up.

Highbeam · August 27, 2003

I've been running the bosch +4s for the last 30,000 miles or so. They were cheaper than the stock replacements that dropped the discs into the combustion chamber. Runs fine. No better than any other new plug.

You can't gap them, dont' need to as they are pregapped platinum plugs.

The extra electrodes don't give 4 sparks. I agree the spark will only go to one. However the electrode that the spark does choose is on the side so the spark is laying sideways as opposed to the typical setup. Maybe this is just in my head but it seems that the spark is more exposed to the mixture. No need to index the plugs.

Also the spark will go to the best electrode. If a piece of crap fouls one of the four electrodes then the spark won't die it will go to another electrode. Seems to add dependability. I could see three of the four being covered with carbon and beign unused, I will check when I pull them for grins.

I will never use the disc droppers again. The +4s worked as well or better and they are cheaper.

BlackSilver · August 27, 2003

Also the spark will go to the best electrode. If a piece of crap fouls one of the four electrodes then the spark won't die it will go to another electrode.

Actually it's just the opposite.

You now have four chances to foul your plug instead of one, and the electricity will always flow the path of least resistance to the fouled electrode, not to a clean electrode.

Highbeam · August 27, 2003

"You now have four chances to foul your plug instead of one, and the electricity will always flow the path of least resistance to the fouled electrode, not to a clean electrode."

Really? I figured a fouled electrode was one that doesn't conduct for beans. No conduction and no spark. If the spark is attracted to the cruddy electrode then great, it is a better condutor than the clean ones.

Same argument though, I have four chances to foul the plug. After 3 electrodes are fouled I have the fourth one left.

Am I missing something? I always thought a clean electrode offered less resistance than a carboned one.

BlackSilver · August 27, 2003

Really? I figured a fouled electrode was one that doesn't conduct for beans. No conduction and no spark. If the spark is attracted to the cruddy electrode then great, it is a better condutor than the clean ones.

Same argument though, I have four chances to foul the plug. After 3 electrodes are fouled I have the fourth one left.

If the electricity flows to a fouled electrode through some crud there is no spark and the engine misfires on that cylinder. You don't want a plug with conduction. Conduction is bad --- spark is good!

A fouled plug isn't just a plug with some carbon on an electrode, it's a plug with some crud which electrically connects the center and the outer electrode, thus conducting and preventing a spark. Plugs with an electrode full of carbon, but without a such a "connectiion" are not fouled, they're just dirty and probably work just fine. (Although the carbon points to some other problem like a rich mixture, bad timing, or a plug which is too cold.)

Chris97K1500 · August 27, 2003

I had them in other vehicles and I didn't notice any gains in anything. Maybe they do, maybe they don't, to each his own! For me, I'll just stick to the old fashion ones. Chris

Highbeam · August 28, 2003

Thanks for the explanation. I knew carbon was a good conductor. I just didn't understand what caused a fouled plug. Would you guess that the spark favors one particular electrode? Or skips around to all 4 as the carbon grows and attracts the spark to the unused tip?

surferdude · August 30, 2003

Highbeam: Did you go with the BOSCH plugs? I picked up a set at NAPA but haven't bothered to install them yet.

Highbeam · September 2, 2003

Yep, Bosch platinum +4. All 8. They were cheaper than the replacement A/Cs and there didn't seem to be any parts that would fall off into the cylinder .

The other option is plain ol bosch platinums but I thought I would try a gimmick plug. The +4s work well. No problems at all. There are certainly other brands out there, I have heard good things about the NGK plugs but they weren't available for my truck.

The only thing I know is that I will not put the POS ACs back in. I'm still mad about that.

ClipperSkipper · September 2, 2003

We've been replacing the OEM spark plugs

in these trucks with AC/Delco platinums, 41-974.

Takes the skip out of the motor, particularly at idle.

Loose the Bosch +4 idea; rapidly.

Have a great one!

Wayne2 · September 7, 2003

Junk in my opinion. Electricity will follow the path of least resistance so there is only one place it will spark. I have had frients put them in and quickly pull them due to truck running worse.

I stuck with NGK TR-55 regular copper. I replace them every 30K. I just think plain copper gives the best performance. All the platinum and iridium do is add longevity. Plus, I had one of the platinum discs disappear on one of my oem plugs. Don't want to know where that ended up.

Ditto what he says. They are a rip off. Spark on vehicle systems is only strong enough to jump to one ground electrode. The others only serve to shield the lone spark from the mixture and impede firing. Also, I am one of those that has lost discs off of stock plugs. I lost 5 on a '98 Trans Am. Had a detonation problem with it ever after too. Don't know if one of them stuck in cylinder and caused detonation or not but I will never use them again. NGKs have given me the best performance.