Motorcraft spark plug confusion?

Hi everyone,

1985 F150/2wd/manual/stock ignition, inline 6 here.

I am doing a tuneup.  After 2x tuneups with Autolite copper cores I am trying to find the right Motorcraft plugs to see if I can notice a difference, but I just realized my Chiltons has a different plug than what I am told I have to special order at all three local shops (SP-420A I think)

From what I have read regarding the topic:

1.)  most people who know their trucks well, say the Motorcraft coppers are the best for the inline 6 (assuming stock ignition/distributor)

2.)  some people use a plug that goes a little deeper into the engine for better combustion (I am willing to try this)

3.)  some people use a Motorcraft plug for the EFI's on their carbed engine, just fine.    

hopefully all reasonable?


So, Chilton's 80-96 (ugh) specifies "BSF44C or equivalent", yet online auto parts stores say this will not fit my vehicle!
Does that mean it's for the 87 and up EFIs?  

The only thing close I can find that's Motorcraft is "BSF44CA" (local Autozone) and the reviews are people with 89/90/95 trucks!  I'm confused.    Sure would like to buy and try...


Is this a matter of threads/hex dimensions?  I can't find much info.  Thanks for anyone that chimes in.

Cheers, Bell

What does the emission label say for spark plugs? For example, Darth's says ASF-42 gap .044-.046

"BSF-42   / .042-.046"   why do I always forget to look at my labels??
  TY

I see, the BSF-42 is now the SP-420 I have been told I need and is not local...


So, next question would be, would I be able to use the 87-up EFI type copper plug, and would it improve performance at all?  I am trying to rule out poor quality spark plugs for a bit of stumbling I have...

I think David changed to the later plugs, so I'm going to tag him.

http://vb.foureyedpride.com/showthread.php?186716-SP450-vs-SP450A

mb757 had the following information regarding spark plug naming convention!  Super helpful.  



"The long part number on the spark plug from Motorcraft will tell you quite a bit about the plug itself, for example ASF-42-C breaks down with the ASF is the seat and thread size ASF is a 14MM tapered seat, BSF is an 18mm tapered seat, AGSP is a 14mm gasket style seat. The 42 is the heat range a cooler plug would be a 32, 22 and so forth, a 44 would be the same heat range with an extended tip. The suffix of a C would be a copper core, P would be a Platinum, and a FM would be a fine wire platinum and so forth. I like to use the long number but the short number causes much less confusion and your chance of handing out the wrong plug are a lot less."

This is what I used for many years:


https://shop.advanceautoparts.com/p/motorcraft-spark-plug-bsf44p-sp-452/18090030-P