Did I get the right plugs?

wavinwayne · May 13, 2005

I just picked up a set of spark plugs for my wife's '97 Expedition 4.6L. They are Autolite Platinum #AP104 plugs. There was a double-platinum plug, #APP104, but those were out of stock. I'm assuming the only benefit to the double-platinums is longer life?

Do any of you Ford guys have any experience with the Autolite #AP104 plugs & do you think they will work ok in the Expy?

Thanks in advance.

brianl703 · May 13, 2005

They'll work fine--just that (in theory anyway) 4 of them won't last as long due to polarity of the spark going through them in relation to where the platinum is. You could even use copper core plugs (the standard cheap ones) in that engine if you didn't mind changing them more often.

From what I have gathered, for maximum life, you really want to use double-platinum plugs with a distributorless ignition system where two plugs are fired at once.

For a distributor type ignition, the single platinum plugs are fine.

The reason for all of this is that only one or the other of the two spark plug electrodes erodes due to the spark, and which electrode it is is dependent upon the polarity of the spark.

Distributor type ignitions use the same polarity on all the sparkplugs. Distributorless ignitions have two plugs in series so half of the plugs will have reversed polarity compared to the other, hence the need for double-platinum plugs.

As a bit of trivia, the factory sparkplugs installed by Ford in the Contour/Mystique through 1997 were of two types, one which has the platinum on the ground electrode and one which has the platinum on the center electrode. They were installed in the correct cylinder so that the platinum would be on the correct electrode in relation to the polarity of the spark current flowing through them. This was likely a cost-saving measure, the service replacement plugs specified by Ford have the platinum on both electrodes and it doesn't matter which cylinder they're installed in.

brianl703 · May 13, 2005

http://www.autolite.com/framer.cgi?page=http://www.autolite.com/products/dis.htm

That URL has a nice picture explaining it.

brianl703 · May 13, 2005

Apparently single-platinum plugs are OK for coil-on-plug applications too:

http://www.motorcraft.com/products.asp?T=2&M=18&PageID=34

Single platinum - Used in conventional distributor-equipped and coil-on-plug ignition systems, these plugs offer 60,000- to 100,000-mile service intervals.

Double platinum - Used for distributorless ignition systems, these plugs improve performance, resist erosion and offer 100,000-mile service intervals.

Whimsey · May 13, 2005

Originally posted by wavinwayne:
[qb] I just picked up a set of spark plugs for my wife's '97 Expedition 4.6L. They are Autolite Platinum #AP104 plugs. There was a double-platinum plug, #APP104, but those were out of stock. I'm assuming the only benefit to the double-platinums is longer life?

Do any of you Ford guys have any experience with the Autolite #AP104 plugs & do you think they will work ok in the Expy?

Wavin,
If you use the single platinum plugs in your 1997 4.6 you will as brian says wear out 4 of the plugs in less than 30,000 miles. You have the the distributorless ignition system not the coil on plug as the 1999 or 2000 and on up have. With it being a MAJOR pain in the butt to change the plugs in our engine I'd get the proper double platinum plugs. It'll be worth your while.

brian, I have a 1996 2L Zetec in my Contour and the factory plugs are as you described, platinum on one electrode only, but installed in specific cylinders. In fact the factory plugs that have the platinum on the center electrode have beige paint on the top of the plug. I assume that made it easier and faster for the assembly line workers to install the correct sparkplug in the cylinder

.

Whimsey

wavinwayne · May 13, 2005

Thanks for your help, guys. I guess I'll hang my head in shame & go get the correct plugs.

Would these single platinums REALLY wear out in 30k?

Whimsey · May 13, 2005

quote:

Originally posted by wavinwayne:
Thanks for your help, guys. I guess I'll hang my head in shame & go get the correct plugs.

Would these single platinums REALLY wear out in 30k?

Don't hang your head in shame! It's the part's guy's fault for pushing the single plat's on you to make a sale instead of saying that they can order the correct plugs and get them the next morning. Personally I would find an auto parts dealer that handles Motorcraft products and get the proper Motorcraft/Ford plugs. They are your best bet. I get Motorcraft plugs through Strauss Auto here in NJ for 1/2 or less than the dealer price. Check the Motorcraft site to see who carries Motorcraft parts near you. The OEM plugs are better especically considering the "PAIN IN THE BUTT" FACTOR IN CHANGING OUR PLUGS. As far as the single platinum plugs wearing out in 30,000 miles or less in your truck the answer is yes they can and do. I'd sure as h*ll hate to have to change the plugs in our engine in 30,000 miles or LESS because I went "cheap" when buying the plugs.

Whimsey

[ May 13, 2005, 07:39 PM: Message edited by: Whimsey ]

brianl703 · May 13, 2005

I do want to point out that I found out that Motorcraft sells "finewire platinum" plugs which apparently are a new development in spark plug technology. They say that these are better than double-platinum plugs..even though they only use platinum on the center electrode.

http://www.v8sho.com/SHO/SparkplugDesign.htm has more details.

wavinwayne · May 13, 2005

Well,
I should clarify something. This morning, I used AutoZone's website to get the Autolite spark plug part numbers. Then, I went to a Wal-Mart next door to my work & purchased the Autolite single Platinum plugs. I returned them & got my money back.

About an hour ago, I went to Autozone & they did not have a total of (8) Autolite Double Platinums in stock. So, I went next door to Advance Auto Parts & they did not have the Autolite Double Platinums in stock.

So, I picked up Bosch Platinum 2 plugs. The name seems to indicate "double platinum", but it appears that these still only have a platinum center electrode. They do, however, have two ground electrodes, where the Autolite single platinums only had one. Will these Bosch Platinum 2's wear out as quickly as the Autolite single platinums?

HELP

[ May 13, 2005, 09:31 PM: Message edited by: wavinwayne ]

wavinwayne · May 13, 2005

Screw it; I'm taking the Bosch plugs back to Advance. Then I'm going back to AutoZone & having them order the Motorcraft double platinums. Then I won't have too worry about it anymore.

SERENITY NOW!

Whimsey · May 13, 2005

quote:

Originally posted by wavinwayne:

Screw it; I'm taking the Bosch plugs back to Advance. Then I'm going back to AutoZone & having them order the Motorcraft double platinums. Then I won't have too worry about it anymore.

SERENITY NOW!

A wise decision

.

Whimsey

wavinwayne · May 13, 2005

I got frustrated & went to the Ford dealer this morning & got the proper Motorcraft plugs #AGSF32FM.

Anybody want to take a guess how much the plugs cost me at the Ford dealer?

Also, when installing the plugs in my Expy 4.6L, am I supposed to use anti-seize on the spark plug threads?

[ May 14, 2005, 11:05 AM: Message edited by: wavinwayne ]

wavinwayne · May 13, 2005

quote:

Originally posted by brianl703:
I do want to point out that I found out that Motorcraft sells "finewire platinum" plugs which apparently are a new development in spark plug technology. They say that these are better than double-platinum plugs..even though they only use platinum on the center electrode.

http://www.v8sho.com/SHO/SparkplugDesign.htm has more details.

Those are the ones I got. We shall see how well they work.

brianl703 · May 14, 2005

quote:

Originally posted by wavinwayne:
Anybody want to take a guess how much the plugs cost me at the Ford dealer?

$7 a piece. Rockauto.com sells them if you don't need them in a hurry..

brianl703 · May 14, 2005

quote:

Originally posted by wavinwayne:
Also, when installing the plugs in my Expy 4.6L, am I supposed to use anti-seize on the spark plug threads?

I would recommend it. Only use a little bit though, don't glop it on there.

wavinwayne · May 14, 2005

quote:

Originally posted by brianl703:

quote:

Originally posted by wavinwayne:
Anybody want to take a guess how much the plugs cost me at the Ford dealer?

Click to expand...

$7 a piece. Rockauto.com sells them if you don't need them in a hurry..

Harbin Ford in Scottsboro, AL. charged my $5.85 each for the plugs.

brianl703 · May 14, 2005

quote:

Originally posted by wavinwayne:
Harbin Ford in Scottsboro, AL. charged my $5.85 each for the plugs.

I once paid $7/piece for plugs from the dealer. I only needed 6 of them, thankfully..

doitmyself · May 14, 2005

Brian,

Thank you for the very interesting information above.

I wonder if this "two different plug" business applies to my son's '99 Escort (non Zetec)..

The first time we changed plugs in it several years ago, I noticed that there were two different ones.

The owners manual says when checking plugs, always put the plug back in the same spot it came out. I vaguely remember paint on the plugs also.

I just thought the previous owner made a bone head mistake!

Did I get the right plugs?

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