Hi Guys,


next weekend i will have to change my spark plugs and coils on my 2003 F150 Harley Davidson.
I searched and read a lot and found different informations.
An especially Information in this forum was this:


"Plugs were getting blown out on the old NON-PI heads, specifically on the Lightning. Under boost, the plugs were pulling the threads out of the heads. In 97, 98, and early production 99 heads, they only had 4 threads. From late 99 until the 3-valve came out, the PI heads have 8."


So is it right that my 2003 F150 doesnt have the Problem with spark plugs blowing out cause it has almost 8 threads?


Next question is about the torque, some people say 14 lb/ft, other say 28-32 lb/ft, what is right


Hope here are specialist that can answer me both questions.


Best regards
Sebastian

 

That is incorrect, bad information.

The problem was not especially endemic to the Lightning, and being supercharged (boost) didn't exacerbate the problem for Lightning owners.

The 4 threads per spark plug hole was a problem for all Ford Modular engines up to the end of the 2002 MY run, and in some cases, into the 2003 MY run, depending on how many heads were left for each size modular engine block when Ford upgraded the spark plug threads.

Sometime near the end of the 2002 Model Year run for the 4.6L, 5.4L, and 6.8L modular engines, and in some cases into the 2003 Model Year run, Ford started using upgraded heads with more threads per hole.

If you have an upgraded head, then the chances are very slim the same problem would affect you, however it is still very important to use the proper torque for the plugs.


The old rec was 12 to 14 ft lbs of torque. I understand the recommendation is now 22 to 24ft lbs of torque. I would research that over in the 6.8L V10 forum to make sure.

Stewart