Autolite double platinums

[mechanicx]

I've always suspected that Autolite plugs were the same as Motorcraft. I've had good luck with the Autolite copper plugs.

If this is for the GM 3.8, I would go with NGK laser double platinums or laser iridium. I've seen too many of the ACDelco double platinum's ground elctrode tab falling off. Do what GM did anyway for later models, use NGKs. It' too much hassle changing plugs in a GM V6 to gamble with anything but NGKs.

 

[mechtech2]

All plugs are kinda identical.
Look closer.

 

[brianl703]

I've compared Motorcraft and Autolite plugs, and the threaded portion was identical, including the markings and stampings. The difference was that the metal on the Autolite was not a dark gray color like it was on the Motorcraft. One of the similarities I noticed was the way the metal was raised around the edges of the hex flat.

If those plugs weren't made in the same factory, the threaded ends were at least engineered by the same person or persons.

 

[mechtech2]

I have never seen autolite and motorcraft spark plugs that were identical. Just the basic similarities.
BTW, the threads have to be almost identical - how could they not?

 

[Audioquest]

I've never had issues with different brand plugs in my 91 Honda CRX. It actually came from the factory with Champion RC9YCN4 spark plugs installed. I've run NGK V-groove, Bosch Plats and Super Coppers and Canadian Tire's house brand NGK-made plugs without issue.

The only two issues with plugs I've ever had was with Champion RN12YC plugs getting wet in my 87 Renault Alliance and failing to start and with Autolites in my 85 Toyota Tercel - poor starting.

 

[Down_South]

Well, I have used NGK, Autolite, Denso and Champion plugs with no problems. a bit of advice for y'all - check the resistance of your plugs and wires before you install them. An ignition system with its resistance balanced performs alot better in the long run and keeps the ignition coil(s) from overheating.

Example: Plug Resistance + Wire Resistance = Total Resistance to cylinder

If the total resistance from one cylinder to the next is about the same, then you should be getting a similar spark in each cylinder. This means you should be getting the smoothest engine performance possible at any RPM. Get A DMM, DVOM or a Ohmmeter and start testing your wire's and plug's resistance. I always combine the highest resistance wire with the lowest resistance plug and so on and so forth. You'll find that resistance in plugs isn't always the same from one plug to another, even if they are brand new and made by the same spark plug manufacturer. Good Luck, Have Fun, and Drive Safe.

 

[PandaBear]

Originally Posted By: Down_South
Well, I have used NGK, Autolite, Denso and Champion plugs with no problems. a bit of advice for y'all - check the resistance of your plugs and wires before you install them. An ignition system with its resistance balanced performs alot better in the long run and keeps the ignition coil(s) from overheating.

Example: Plug Resistance + Wire Resistance = Total Resistance to cylinder

If the total resistance from one cylinder to the next is about the same, then you should be getting a similar spark in each cylinder. This means you should be getting the smoothest engine performance possible at any RPM. Get A DMM, DVOM or a Ohmmeter and start testing your wire's and plug's resistance. I always combine the highest resistance wire with the lowest resistance plug and so on and so forth. You'll find that resistance in plugs isn't always the same from one plug to another, even if they are brand new and made by the same spark plug manufacturer. Good Luck, Have Fun, and Drive Safe.


I'd have to say no.

When firing, the resistance across the gap of the plug is the resistance of the air fuel mixture. If you look up a resistance table air is much closer to vacuum than any metal or graphite core wire. It is so high that the plug gap is a bigger factor to the resistance than anything else.

When the voltage reach a certain level that trigger what is called a "di-electric break down" aka firing in automotive term, this gap will become very low in resistance and most of the energy from the voltage difference charged up by the coil till then is released. At this point, the gap is like a capacitor that release its energy and most of the current doesn't go through the coil or the wire at the time, so you cannot use the typical circuit theory to model it.

The firing voltage is determined by the surface size (sharpness of the gap), the material of the surfaces (steel, platinum, or iridium), the size of the gap, and the material between the surfaces (air fuel mixture).

The main benefit of using exotic material is to either increase the gap by reducing the surfaces, or increase the life, not reducing the resistance of the circuit. If you look at how much platinum or iridium it uses on the tip and how irreverent it is to the firing voltage, you can see that it is not the resistance of the material but the firing voltage that the material makes a difference on.

 

[ProStreetCamaro]

I am not a big platinum fan at all. I have found wayyyyyyy to many with the platinum on the ground strap completely gone. Gee I wonder where that went? Good old copper for me or maybe iridium but no platinum.

Example would be the LSX community gets great results out of TR55 plugs which are NGK copper plugs. That happens to be what I replaced the plugs in my 99 SS Camaro with along with MSD wires. Runs like a champ.

 

[Down_South]

OK, let me get this right...

"...It is so high that the plug gap is a bigger factor to the resistance than anything else...."

if this is the case, then why wouldn't you want to balance resistance across the system?

 

[PandaBear]

Originally Posted By: Down_South
OK, let me get this right...

"...It is so high that the plug gap is a bigger factor to the resistance than anything else...."

if this is the case, then why wouldn't you want to balance resistance across the system?



Here is a quote I found online from powrearc.com

Quote:
"R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.

You must use resistor spark plugs & wires in any vehicle that uses electronic ignitions or on-board computer systems to monitor or control engine performance. This is because resistor spark plugs & wires reduce (EMI) electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, or whenever recommended by the manufacturer.

In fact, using a non-resistor plug or low resistance spiral wound spark plug wire in most applications may actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels, abnormal combustion and probable damage to the ignition and/or ignition coil.


5k ohm is HUGE compare to variation of resistance between different types of metal (aka any conductor) of near 0 in comparison.

The only reason a resistance matter in the system is when there are sudden change from open to close circuit (firing), the speed of the switch will cause a lot of problem if there is no resistance and capacitance/inductance to filter out the noise.

So, when there is 5k ohm +/- 5% variation or so in place in some system, why would you care to optimize 1-2 ohm of resistance?

 

[brianl703]

Originally Posted By: mechtech2
I have never seen autolite and motorcraft spark plugs that were identical. Just the basic similarities.
BTW, the threads have to be almost identical - how could they not?


It's not just the threads, it's the markings on the hex flats, the way the numbers and letters are stamped into the metal(size and font), the size of the hex flat (how tall it is), how tall the metal above the hex portion is, how many ridges/grooves in the metal there are between the threads and the hex portion.

Moving onto the insulator end, you will find that both the Motorcraft and the Autolite plug have the same number of ridges and they are located in the exact same position on the insulator. There isn't a millimeter of difference in the position of those ridges from the Motorcraft to the Autolite plug.

All of these are similarities between the Motorcraft and Autolite plugs that you won't find between a Motorcraft and a Champion plug, or a Motocraft and a an AC Delco plug.

It's very obvious that the Motorcraft and Autolite plugs were produced from the same drawing.

 

[mechtech2]

The resistance between the electrodes is the biggest resistance n the circuit, by far- more than far. [This refers to the gap that must be jumped]
And this varies with compression and running conditions.
Full throttle increases the resistance a lot.

Platinum tips are standard and very good. Tips that 'fall off' are usually because they were not there in the first place because of common waste spark ignitions, or they are very tiny.
Autolites can have extrememly small platinum nubs.
Also they do wear, but at a slower rate than steel.

 

[Down_South]

Originally Posted By: PandaBear
Originally Posted By: Down_South
OK, let me get this right...

"...It is so high that the plug gap is a bigger factor to the resistance than anything else...."

if this is the case, then why wouldn't you want to balance resistance across the system?



Here is a quote I found online from powrearc.com

Quote:
"R" or resistor spark plugs use a 5k ohm ceramic resistor in the spark plug to suppress ignition noise generated during sparking.

You must use resistor spark plugs & wires in any vehicle that uses electronic ignitions or on-board computer systems to monitor or control engine performance. This is because resistor spark plugs & wires reduce (EMI) electromagnetic interference with on-board electronics.

They are also recommended on any vehicle that has other on-board electronic systems such as engine-management computers, two-way radios, GPS systems, or whenever recommended by the manufacturer.

In fact, using a non-resistor plug or low resistance spiral wound spark plug wire in most applications may actually cause the engine to suffer undesirable side effects such as an erratic idle, high-rpm misfire, engine run-on, power drop off at certain rpm levels, abnormal combustion and probable damage to the ignition and/or ignition coil.


5k ohm is HUGE compare to variation of resistance between different types of metal (aka any conductor) of near 0 in comparison.

The only reason a resistance matter in the system is when there are sudden change from open to close circuit (firing), the speed of the switch will cause a lot of problem if there is no resistance and capacitance/inductance to filter out the noise.

So, when there is 5k ohm +/- 5% variation or so in place in some system, why would you care to optimize 1-2 ohm of resistance?


Because that's 1-2K ohms less stress on the ignition system which makes jumping the gap slightly easier. Don't believe me, just raise the resistance in the wires and plugs by as much as 5-10K ohms and eventually you'll be sitting on the side of the road with burned up ignition coils.

The Champion plug for my application had a resistance of 15K ohms and the ignition coil burned up within 2 years, I changed to an Autolite plug with 5K ohms and the coil hasn't been replaced in the 5 years since I've installed it.

 

[1kickbuttranger]

Actually the Motorcraft plugs are made by the same company that makes Autolite for certain applications. There may be plugs that are boxed as Motorcraft that are Japan made for certain engines.

What is for certain is that they come from the same factory, what is uncertain os if they are "exactly" the same.

Both plugs in the picture are made in the USA, as both have this engraved in the metal portion between the hex and the threads.


Here are some comparissons from some used plugs that I have laying around.

The Motorctafts are double paltinum AGSF32PPM, and the Autolites are the same equivalent APP104.

 

[1kickbuttranger]

Also, Motorcraft doesn't make a double platinum any more, they have gone to a fine wire single platinum, but I believe Autolite makes a fine wire double platinum. So the only plug I would feel comfortable running in a DIS/EDIS would be the APP's.

-Here is the problem-
The last time I went to AZ to buy a set (APP104's) they looked different... almost cr appy. I looked on the ring, and no where did it say Made in the USA on it. The box said Made in Mexico.

Needless to say I passed on them, and found a hole in the wall B&M parts store that the guy was able to look way back on the shelf and find me 7 USA made ones. (I bought all 7 even though I only need 6) I paid a bit extra, but hey, I got what I wanted.

The picture posted of the box is divided- half gray and half white on the USA made plugs, (pictured)... the ones that are Mexico, the side flaps are entirely white.

To me they don't look the same.

 

[PandaBear]

Originally Posted By: Down_South

Because that's 1-2K ohms less stress on the ignition system which makes jumping the gap slightly easier. Don't believe me, just raise the resistance in the wires and plugs by as much as 5-10K ohms and eventually you'll be sitting on the side of the road with burned up ignition coils.

The Champion plug for my application had a resistance of 15K ohms and the ignition coil burned up within 2 years, I changed to an Autolite plug with 5K ohms and the coil hasn't been replaced in the 5 years since I've installed it.


Wire has to be less than 10 ohm (not 10k ohm) for it to be consider working. Metal wire are almost 0 in resistance (no more than 10 ohm for a distance) as well, what you are talking about in resistance is between one plug brand/type to another, not the difference between steel/copper/iridium/platinum.

http://en.wikipedia.org/wiki/Resistivity

Iron = 1.0 x 10^-7 ohm meter
Platinum = 1.06 x 10^-7 ohm meter

http://en.wikipedia.org/wiki/Electrical_conductivity#Some_electrical_conductivities

Air = 0.3 to 0.8 x 10^14 ohm meter


Tell me how Iron/Steel is significantly worse than Platinum (both are copper core internally), and how is this resistance going to make a difference over the air's resistance when it is 10^21 times bigger (that's 10 to the power of 21, close to infinite).

You cannot get 1k ohm out of any metal without significant length, that got to be something like hundreds of feet of metal wire to get 1k ohm of resistance. The difference in resistance is from the resister they put inside the plug that is not a pure metal (metal oxide, carbon, thin film of something, etc) and not the metal tip that they put at the terminal of the gap .

 

[mechtech2]

Motorcraft still makes double plats [Unless they changed in the last 6 months]. They did change their numbering system for replacement parts.

The center electrode looks like a different design between the 2 plugs in the pictures above.

 

[Down_South]

Dude, Get a DMM and see for yourself. I'm not talking about electrode material resistance, nor am I talking about eliminating resistance completely from the system. I'm talking about balancing the resistance that already exists in the ignition components. Like I said earlier, get a DMM and see for yourself.

 

[PandaBear]

Originally Posted By: Down_South
Dude, Get a DMM and see for yourself. I'm not talking about electrode material resistance, nor am I talking about eliminating resistance completely from the system. I'm talking about balancing the resistance that already exists in the ignition components. Like I said earlier, get a DMM and see for yourself.


Fine, even if you match the resistance between cylinders, how are you going to match the resistance of the gaps between the cylinders, and how many times you have to match it, and how often you have to do this over the life of the plugs? They don't wear the same due to cylinder condition differences (i.e. compression differences).

Not really something practical for a typical owner that just want a ride to work.

 

[Vikas]

Anybody remember "indexing"?