All,

First I wanted to say that I've looked over the search results. However, I was hoping to find better consensus here.

The Owners Manual for my 2001 Ford Ranger XLT 4.0L SOHC, states two items: First on page 229, "Refer to Vehicle Emissions Control Information (VECI) decal for spark plug gap information." Following that guidance, VECI specifies that the spark plug gap should be 0.062"-0.068". However, on page 235 within the 'Engine Data' table, it indicates that the 4.0L should have a spark plug gap of 0.052"-0.056".

The question I pose here is: which specification do I follow? Right now I'm leaning towards the low end of the VECI recommenation w/ a gap of 0.062".

 

Yes, gap at .062

Also only use double platinum spark plugs(or just copper), you are running a Waste Spark system, this means one bank of the engine sparks from center to tip(normal spark), but the other bank sparks from tip to center(reverse spark)
So either both tip and center need the coating or neither does, single platinum will wear out just like regular copper on one bank, so a waste of money

The Waste Spark system is why you will often see TWO different spark plugs listed as stock/factory spark plugs
Because Ford used two kinds of signal platinum spark plugs, platinum tips on one bank and platinum centers on the other
When you are FORD and buying a million spark plugs at one time then economically this makes sense, but when buying just 6 go for the double platinum, lol.

 

Thanks for the response!

The Motorcraft double platinum plugs (Part No. AGSF34FP) were all pre-gapped at 0.062" +/- 0.001". I was pleased about that.

Removing the existing plugs wasn't as difficult as I initially anticipated, but I certainly spent the majority of my time on two difficult plugs (No. 2 and No. 4) due to tight clearances around the a/c components and egr plumbing. I had to use the breaker bar for starting several of the plugs; I made sure to use a decent amount of anti-sieze on the threads of the new plugs and hand tightened.

One interesting note about the existing spark plugs: Bosch platinum plus (No. 4005) with an average gap measured at 0.040". Many of these plugs were very difficult to remove.