Difference between these 2 types of Motorcraft plugs

[WTL]

So im trying to find someone who can tell me or tell me where to look for the difference between these 2 plugs - both Motorcraft - Ford. I cant find a motorcraft number, ford c/s says call the dealer and the dealer doesnt know. Hell, ford c/s actually gave me a number for a tech line and it ended up being there retails number for sales for clothing. Then i got a number for Ford Power Products which actually sells car generators!!! Im surprised anyone knows what the hell is going on over there.....

SP-400, AGSF22N AND SP-521, AGSF22F1

Tks much

 

Sorry, not sure what’s up with the black background. Also, wasn’t sure where to post this.....

[JFP in PA]

AGSF22N

 

AGSF22F1

 

 

 

 

[WTL]

Tks. Doesn’t seem to be much difference - BUT - I’m no expert. Clearly there is a difference between oreily and autozone where I went - they could tell me nothing.....  After trying motorcraft and Ford , I was cooked.  These are actually for my Generac generator....  Generac sells them for 26 dollars a piece!  One service co.  said one was an oem crossover while another dealer said the other and Generac refused to give a crossover number understandable, I guess.  I don’t know enough about this stuff to know if the tip material nickel vs platinum and the electrode design fine wire vs standard means much?  It’s a Ford, 5.4L V8.  Curiously, this is what the old ones looked like - which were the SP-521’s....

[JFP in PA]

Just a suggestion, but it would seem you are overthinking this a bit, plus I wouldn't use either plug in the generator.  For some years now, iridium plugs, which outlast and outperform just about any other plug technology on the market in the harshest spark plug applications, have been available.  As your standby generator has to work when you need it to, I would be looking for an Iridium plug cross reference for the Motorcraft plugs and simply forget about what the manufacturer recommends.

 

I have personally used Denso Iridium plugs in everything from my Porsche, to my 33 Kw Kohler standby generator, to my leaf blower, and never had any issues, which is the way I like things to be.  😉

[JFP in PA]

51 minutes ago, WTL said:

Tks. Doesn’t seem to be much difference - BUT - I’m no expert. Clearly there is a difference between oreily and autozone where I went - they could tell me nothing.....  After trying motorcraft and Ford , I was cooked.  These are actually for my Generac generator....  Generac sells them for 26 dollars a piece!  One service co.  said one was an oem crossover while another dealer said the other and Generac refused to give a crossover number understandable, I guess.  I don’t know enough about this stuff to know if the tip material nickel vs platinum and the electrode design fine wire vs standard means much?  It’s a Ford, 5.4L V8.  Curiously, this is what the old ones looked like - which were the SP-521’s....

 

OK, let's separate the wheat from the chaff on plug construction; assuming the plug is the correct thread size, heat range, and length for the application, the next biggest question is the materials of construction.  Durability is a function of what the electrodes are made of, and falls in a simple order from the most durable to the least: Iridium/platinum/nickel/copper. In a car engine, an iridium plug can easily go 100K miles in a harsh application, while a copper plug may need to be changed out after only 20-30K miles simply because the copper is the least durable metal.

[WTL]

Tks Jeff. Part of the issue as mentioned is that generac refuses to give a crossover part no. and what I get from dealers are the 2 above which are different.  generac referred me to ordertree.com and even those guys could tell me nothing - but only sell me the part.  I guess I could spend the 27.00 bucks and order one to see what I get.  I have been told that I do tend to overthink things.  I also get a lot, "Ive never been asked that before".  And this tends to be a good example of why I guess.  I wrench a little but not nearly as much as others. But I am a manual guy and figure the manufacturers put stuff in them for a reason.  Problem is that im getting a little too old to be climbing up and down the roof to work on the gen and the people around here charge outrageous prices and while I don't mind paying market rate, I think 27.00 bucks is a bit steep.  I refuse to pay 900.00 I was quoted for a 3 gal rad flush and the service co wanted over 500.00 for a serpentine belt change - not including the part. But maybe its more involved that the V belt change I did - nothing to remove there.  I haven't inspected it closely yet.   I understand they are in business to make a profit and I endorse capitalism, but its seems excessive to me.  So im left trying to figure this out on my own, trying to make sure I don't screw it up and with all the poorly trained counter help and googling, its tough.  So your help is much appreciated.  Without a benchmark or OEM start point, to be sure.  I guess I need to order one and see what I get in order to know what I can safely use.  Based on your above response, iridium may be the ticket to get peace of mind and longevity and superior performance all other things meeting required specs.  

[JFP in PA]

You don't need to use the dealer to get this type of information, there are websites that list every known plug type to every brand known to mankind.  The two plugs you noted above are exactly the same, other than their electrode metals; one is platinum, the other nickel; otherwise they are exactly the same.  Summit Racing sells the Motorcraft AGSF22N for $4 each, Advanced Auto Parts is closer to $5.  There is no magic here, Generac is trying to screw you on the part, which is common.  My 33 Kw Kohler used an air filter that they sell for $45, Wix makes it for them and you can buy them on Amazon for $7, you just need to know what to ask for.  Amazon sells your original SP 521 plug for $9.  https://www.amazon.com/Motorcraft-SP-521-Spark-Plug/dp/B004A2BGC0

 

Generac does not make their own spark plugs, they buy them and mark them up to sell it uninformed buyers that do not know any better.  A very little knowledge goes a long way towards saving money 😉

[WTL]

yep.  that's basically what ive been trying to figure out.  and because all I can get is a generac number, I do not know what I should be putting in the generator engine.  the 2 dealers I talked to gave me 2 different plugs - that's why I asked.  so, maybe in this case the "more is better" thinking, i.e., platinum vs nickel, may be the way to go.  All I know is what came out, not what is OEM.  Because I have not always done it myself - mostly - not always.  I cant find what it came with.  But now we get back to the overthinking......  I just wish Generac wouldn't treat it like a national secret.  All good.