I own a 1999 F-150 5.4 V8 Triton.Is there a permanent way to fix the sparks plugs from popping out of the cylinder head? like put on cylinder heads with a longer thread pitch?

 

Just tighten them correctly, all you have to do.

 

I recommend you overtorque them a little bit past the original Ford specs. I've never had mine pop out, I have replaced them 3 times.

Watch this video very helpful
https://youtu.be/kc4-z-sT1ms

 

Did you have a spark plug blow out?
One of the best repairs is the Timesert kit.
The Timesert inserts are stainless steel.
Installing a Timesert insert in all the cylinders would cost a lot less than a new set of 8 thread heads that can still have a blowout.
Steel plugs in aluminum heads is not an ideal combination.
A plug may start to work loose after a lot of miles in the 4 or 8 thread heads.
I read a post from a person with an OEM plug blowing out at 68K.
The blowouts seem to increase after 100K.
Change the plugs/boots/springs and torque to 20-25 ft/lbs every 50k and the chance of a blowout is reduced a lot.
At the very least check the torque every 40-50k.

 

You could get a set of 2004 and up 2v heads. They have 8 threads per hole vs the 4 we have originally. You can use a 2004 Expy or 2004-09 Van with 5.4 and get those heads. Some of the SD engines also fit in this from 04. I looked them up for another person and found them from 125 to 200 per head. I'm sure there are more that are higher, but if you go to Hollander and put in 04 E250 and look for heads, they will pop up everywhere.