Spark plugs

[Msfitoy]

Anyone know the difference between Motorcraft SPARK PLUG CYFS12YT4 and CYFS12YT? I know the second one is stock. Thanks.

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[P. A. Schilke]

Anyone know the difference between Motorcraft SPARK PLUG CYFS12YT4 and CYFS12YT? I know the second one is stock. Thanks.

Hi Sid,

Could this 4 be that this is a 4 pack of spark plugs? I vaguely recall it was a 4 pack. Just a guess...always ran Champion in my race car as they gave two boxes free each year...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

 

[Porpoise Hork]

Hi Sid,

Could this 4 be that this is a 4 pack of spark plugs? I vaguely recall it was a 4 pack. Just a guess...always ran Champion in my race car as they gave two boxes free each year...

Best,
Phil Schilke
Ranger Vehicle Engineering
Ford Motor Co. Retired

You would be correct sir. It's the same plug, just in a 4 pack.

 

[Msfitoy]

Well thank you gents for the fast reply...I was about to install them but notice the number and also the connector tip was yellow instead of red...wasn't sure if that it was hotter or colder...do you think the yellow and red makes any difference?

Also, I notice there's other variants with 3 at the end? 3 pack?

 

[Porpoise Hork]

The SP534 CYFS12YT3 plugs were superseded with the SP580 CYFS12YT4 plugs. They have the same heat range, and from what NGK indicates there may have been issues with the SP534's and similar variants causing misfires.

 

[Msfitoy]

The SP534 CYFS12YT3 plugs were superseded with the SP580 CYFS12YT4 plugs. They have the same heat range, and from what NGK indicates there may have been issues with the SP534's and similar variants causing misfires.

So the 4 designation at the end does not mean 4 pack? How is SP580 CYFS12YT4 different from stock SP580 CYFS12YT?

 

[TheKracka]

I have a different part #
Motorcraft SP578 Iridium Spark Plugs (4pk) Ford CYFS12YPT

 

[rltriumph]

With the part numbers changing is the gap still .030?

 

[Porpoise Hork]

So the 4 designation at the end does not mean 4 pack? How is SP580 CYFS12YT4 different from stock SP580 CYFS12YT?

Honestly Ford has too many variants on their plugs, and what applications they are for... Really causes some confusion when looking for the right one. Especially then they supersede one version for another but are still available for purchase from retailers.

Everything I can find is the actual part number for this plug is SP580 CYFS12YT4 and is listed for the 3.5L and 3.7L V6's. It is available in singles from Ford, comes up as a 4 pack from most third party vendors with a couple also having a 6 pack of the same part number. The only mention of the CYFS12YT I can find is from a few international vendor sites but when pulling it up it lists as a 4 pack and packaging shows it as SP580 CYFS12YT4. Also as @TheKracka mentioned the SP578 CYFS12YPT plug is the correct plug for the 2.0L I4, 2.7L I4, and some 3.0L and select 3.5L V6's.

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