4.6 coughed out a spark plug

Michael Soldan · Jun 17, 2019

Well my F150 4.6 coughed out a spark plug. Mechanic thinks he can fix it with a Heli-coil. I watched a couple of youtube videos on using heli coils. Just how reliable is this fix going to be or should I bite the bullet and pick up a head at the auto wreckers ?

ttocs · Jun 17, 2019

its the best alternative to replacing the head. When done right they can hold up but its not something that either ford or a race car would want or recommend.

96blak54 · Jun 18, 2019

The brand "time-cert" and " locknstitch" are the best fix. Helicoils are cheap fix, but back out over time.

Should you decide replacing the head/ heads. Look for 04-up model years, duch as crownvics, town cars, Econolines, and service trucks with 2v engines. Their heads have 8 threads in the sparkplug holes

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OLD H2S · Jun 18, 2019

I have used the Timesert 5 times on friends different F-150s, good and strong, helps if you use the big kit instead of the cheapy ones. Then I started to put them in all my heads, 8 at a time

az97cobra · Jun 29, 2019

While my engine was at the machine shop I had them add the timesert inserts to all plugs. they told me they install them all the time and have done more than 500. After I went to the track the first time and went to pull the plugs and have a look, 5 of the inserts came out. I called the machine shop and they said they've never seen that before and he seemed sincere. What the hell happened I wondered? Are the inserts unreliable if used on the track? I didn't over torque the plugs since I always use a torque wrench so I don't want to get into a battle over torque here.

ttocs · Jun 29, 2019

ttocs said:
its the best alternative to replacing the head. When done right they can hold up but its not something that either ford or a race car would want or recommend.

for track use you really don't want band aids on the motor or they come off. that is all this literally is, is a band aid/best available fix for a bad design.

OLD H2S · Jul 2, 2019

You torqued the plugs too tight, max is 15 pounds and 11 is the norm.
When new the inserts must be heat cycled to set the lock tight and the plug torque was higher than the insert torque.
Glue them in again with green bearing retaining compound and use a torque wrench...really. I try to guess the torque and then check and I am both over and under.

az97cobra · Jul 3, 2019

I did find online a Loctite 620 which goes up to 450deg. Most of the others I found only go to 300deg which doesn't seem sufficient.

for track use you really don't want band aids on the motor or they come off. that is all this literally is, is a band aid/best available fix for a bad design.
Not sure what to do with this statement. I'm not going to toss these ported heads.

ttocs · Jul 3, 2019

no one enjoys writing the check for new heads and figuring out what to do with the old stock ones no matter ported or not. I am not saying they are complete crap and to ditch them. Use them till you are tired of messing with them but I would start keeping your eyes open for the next set if your going to continue at the track.