You seem to be taking a lot of offense where none is intended.

I realize I don't know everything about engines :o, which is why I'm asking. And I'm not trying to discredit anyone. In fact, I specifically said I'm not calling anyone a liar, but I want to understand. And I agree that drawing from others' knowledge and experience is very valuable, which is exactly what I'm trying to do. But I want to know more than just the fact you and others think they suck. I want to know why they're subpar. Why do people have bad experiences with Bosch plugs? Why are Motorcraft plugs better? Again, I'm not saying you're lying. I'm digging for more information so I can understand.

As for the search bar, I tried that, but while there are many posts about the subject of spark plugs, none I read explained the differences between plugs, which is what I'm trying to understand.

And I'm not saying Motorcraft doesn't make quality parts, or that Ford engineers don't know what they're doing when they specify parts. Certainly the parts they specify meet all the technical requirements necessary for the particular application. What I am saying is that it's possible for other manufacturers to make parts that also meet or exceed the same technical criteria and may be of equal or better quality, for a comparable or lower price.

There's an innate conflict of interest with specifying owners must buy one particular product by one particular manufacturer and then making money off the sale of that product. Ford doesn't make all Motorcraft parts, but they do own the brand name and make obnoxious amounts of money selling Motorcraft parts at their dealerships (which parts, if available elsewhere, are almost certainly much cheaper elsewhere, but Ford still receives some money for owning the brand).

So I'm trying to be an intelligent shopper and become informed so I can make good decisions. I really don't understand why this offends you so, unless you own gobs of Ford stock.

 

I explained the problem, - the important end of things anyway. Ford specs a heat range for thermal performance and believe or not, some plugs don't make the cut. The temperature of the spark plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. This is determined by the heat range selected.

Keep in mind spark plugs do not create heat, they only remove heat. They pull unwanted thermal energy away from the combustion chamber, and transfer the heat to the engine's cooling system. The heat range is defined as a plug's ability to dissipate heat. This was the apparent problem I had with the Autolites (pictures/explantions that weren't good enough for you were posted, -1 page back). The Autolites could not transfer/dissipate adequately = wrong heat range. The plugs over heated in a sense and began to fail. Their not manufactured to Fords "Heat Range specifications" .

Denso's and NGK meet spec and they work fine in the modulars.

I don't own Ford stock. I also don't run Motorcraft plugs.

 

Thanks! That's exactly the type of information I was looking for.

Do you happen to know where this heat range information is shown on aftermarket parts? It's shocking to me that AutoZone and other reputable retailers will sell these parts which don't meet manufacturer specs as "direct replacement" parts.

It sounds like the Bosch plugs people are having problems with are the regular single-ground plugs. I wonder if the Platinum +4 plugs may be built better or to the right temperature range? Like I said, I've got over 80k on a full set of these with no ignition problems (until I recently had to replace my COPs, which I apparently should have done many miles ago anyway). Or maybe I just got lucky.

I was looking at the Densos on Mike Troyer's site and he sells the plugs in several heat ranges, and explains under what circumstances (mods) you may want to use something other than stock spec.

I'll almost definitely use these Denso plugs when I do my rebuild.

Thanks,
Jeff

 

Good grief - Motorcraft plugs aren't any more expensive than Autolite or Bosch - why even bother with anything else unless you want the EXPENSIVE Densos?

Sometimes I think you people automatically think anything from the manufacturer just can't be as good and are more expensive than aftermarket parts..........maybe this was the case 30 years ago but it sure isn't now.

 

why use anything unless its the factory parts, everything on my truck that has been replaced has been replaced with motorcraft parts (except the converters GEEZ those are high) the only thing motorcraft i DONT use is motor oil

 

GLC- I agree with what you said, but wanted to add 1 thing. I personally don't believe Denso's are expensive. Not because they don't cost a lot, but because they simply don't wear out. The Iridium's that is. I changed the plugs in my DIL's Lexus RX at 97k mi.- the plugs had never been out. I bought the plugs before I started to work on the car, which by the way was running fine. When I pulled the plugs, I was amazed- they looked like they had 10-15k mi. on them. You're not supposed to gap those plugs, but I did check the gap. Exactly the same as the new plugs I put in. Iridium is supposed to be the hardest metal known to man, and I believe it. If I hadn't already bought the new plugs, I never would have. Others have had the same experience with the Denso and NGK Iridium plugs. By the way, though the plugs list for about $22.-$24. each I was able to buy them online for about $8. ea., and even picked them up because the dealer was local.

 

Just a little visual of what Bosch plugs can do at 600 miles. Bought this complete motor off a guy that said he put Bosch in for a customer and thought the valve was burnt so he pulled the motor. This is what I found:

 

Yea, my Denso's were under $40 - 36 or 38 bucks for a set from Rock Auto when I ordered. That's all they were, I was surprised. Installed them last winter - Runs Great! Empty or loaded. Very happy with them so far

 

Was that for the Denso Platinums or the Iridiums? I've never seen that low a price for Iridium plugs. Like code58, $8 apiece is the best I've found, and that's what RockAuto.com is quoting now (DENSO Part # 5325 {Iridium Power #IT16} : $8.01).

If Iridiums, you got a steal! I'll have to check back once in a while for a sale.

 

Yea, I know their IT's. Hang on, yea their Iridium's -



WAIT! They come in a box of 4 - It had to be around $35 per box I bet, -My Bad :o - I couldn't have got all 8 that cheap, unless they made a mistake. I am going to find the reciept tho.

 

Here is a link to the NGK plug site that explains very well about the heat range. Pay close attention to the Insulator nose length explanation. While two plugs may look alike they are not.

.

 

Thanks jbrew,

Here is the link; http://www.ngksparkplugs.com/techinf...000&country=US

Regards

Jean Marc Chartier

 

That's a Great pick torkum!! I remember when you purchased that motor. I've seen allot pre-detonation (heat ups) pics of the Bosch plugs, but haven't seen a pick of valve compromise.

Yea , when they heat up they sever right before the bend. That little piece has to go somewhere.

I'm glad those Autolites I tried didn't get THAT hot, but they did get hot enough to turn colors. Installed those Autolites after work at night. Left the next morning , 5 miles to the e-way, about 5 more miles on the e-way I had one cylinder start to mis. Blinking CEL. On the way home that night, she was running terrible,- CEL was on solid.

I ended up re-installing my old Motorcrafts temporarily (nothing was open, we were working 80 hrs per week then) until I could get around to get a new set Motorcrafts.

Changed the the plugs 3 times inside of two weeks. - That was fun

 

No problem man