BE1I is the part number. 25.99 for a 2 pack.

That number is also listed for the 07 and below as well as the 3.7l.

 

Be1I is the correct part number, but advance auto sells the 2 pack for 12.99

 

Bobby is that NGK 4644 for the 4.7 or the 3.7 or are they the same? I put the autolite 3923 and i think it's actually running worse with them in it....

 

4644 is an autolite 3922. Ngk 2756 is a 3923 pregaped at. 044.

 

so which on is for the 4.7?

 

2756 are one step colder than factory champions and come pre gapped at. 044. They should be direct bolt ins.

 

4644 should be the same heat range as 3923s, and they should work in both 3.7l and 4.7l 05-07 engines. The 4644 is the NGK BKR7E, the 3922 cross references to the BKR7E-11 or the NGK 5791.

 

The 3922 interchange to 4644, and 3923 interchanges to 2756.

 

Do you have a link to the cross reference showing this? Anything Im pulling up isnt showing the 4644 directly going to a 3922 plug. Blown runs the 4644 and stated its one range colder than stock, 3922 would be 2 ranges colder, correct?

 

its more like 1.5 steps colder. The stock plug is 6987/zfr6f-11g which is a "6" heat range but extended tip.

here and here are links showing the differances between heat ranges. 70-100 degree change per heat range. Extended tip changes the plugs the plug temp by 25-70 degrees, but i cant find the link.



Here is a page showing the long ngk #. The box your spark plugs came in should have both numbers. 4644=bkr7e and 2756=bkr6e-11.

here are two pics i pulled from the autolite catalog.
4644/bkr7e showing cross reference to 3922.



and 2756/bkr6e-11 crossing to 3923.



also here is a pic from the ngk catalog showing the naming convention for ngk plugs.


Edit: a pdf for the ngk naming convention.
http://www.stealth316.com/misc/ngk-partnumberkey.pdf