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Designed and manufactured by Heli-Coil to provide specific and unique benefits to high-temperature, high-performance spark plug applications.
Heli-Coil spark plug screw thread inserts are manufactured from 18-8 round stainless steel wire formed into a 60° diamond-shaped wire. This cold-worked wire, which has a tensile strength of 200,000 PSI, is wound into a helical coil with a driving tang and notch to remove the tang after the insert is screwed into the Heli-Coil tapped hole.
In its free state, the insert is larger in diameter than the tapped hole. Once installed, the insert assumes the configuration of the tapped hole. The resulting outward spring-like action anchors the insert in place. The Heli-Coil spark plug insert becomes an integral part of the cylinder head, providing high-strength threads which exceed in surface smoothness, hardness, and accuracy any threads tapped in any material.
Use chassis grease in the threads to catch the filings and keep them out of your engine, then put your shop vac over the hole to suck out any remaining chips.
Get a Helicoil kit. They're cheap most auto parts stores have them. You don't drill just screw the tap in. Pack the flutes with grease so metal chips will not go into the cylinder as best you can. Then install the short Helicoil. After it's installed remove the tang with a pair of needle nose pliers. Then you are good to go. Don't get scared by the horror stories of what might happen. On the 2007 Ford and other years the spark plugs break off in the head. The repair is to beat the center of the spark plug into the cylinder and drill the plug body out. Then you are supposed to blow all of the debris out the exhaust.
WOW, when I started typing there were no comments.
Make SURE that the cylinder that is being "thread chased"...has the PISTON in the highest position in the cylinder...this will make SURE that any particles from the thread chasing are at the Highest point ( easiest to vacuum out)...VS.... the piston at the bottom of the stroke...
......Mark
Last edited by sidepipe seeker; Mar 8, 2019 at 07:53 PM.
Make SURE that the cylinder that is being "thread chased"...has the PISTON in the highest position in the cylinder...this will make SURE that any particles from the thread chasing are at the Highest point ( easiest to vacuum out)...VS.... the piston at the bottom of the stroke...
......Mark
Prior to resorting to "heli-coiling"...I personally would make every attempt to restore/use the original spark plug threads....the thread chaser/s are machined such that ...they will chase into maligned/stripped threads...
I Strongly Suggest to everyone that after removing spark plugs...ALWAYS thread chase the spark plug threads...cross threading/ stripping spark plug hole threads is most commonly a result of dirty threads...
The time tested adage of...."An ounce of prevention is worth a pound of cure"...is directly applicable!!.
Also USE a torque wrench and torque to factory torque specs....Guessing is NOT your friend!...Mark
Last edited by sidepipe seeker; Mar 8, 2019 at 08:22 PM.
Use chassis grease in the threads to catch the filings and keep them out of your engine, then put your shop vac over the hole to suck out any remaining chips.
- sounds like to might be "screwed" … … sorry; bad pun.
Make SURE that the cylinder that is being "thread chased"...has the PISTON in the highest position in the cylinder...this will make SURE that any particles from the thread chasing are at the Highest point ( easiest to vacuum out)...VS.... the piston at the bottom of the stroke...
......Mark
This. Surely the threads are just crossed up (unless aftermarket aluminum). Carefully try starting a thread chaser and see if that doesn't clean them up before going the helicoil route.
Chase before committing to Helicoil. Raise piston to top, put a small oiled rag in the cylinder before chasing. Any chips will stick to the cloth and will come out when the rag is removed by grabbing it with a pair of tweezers.
Make SURE that the cylinder that is being "thread chased"...has the PISTON in the highest position in the cylinder...this will make SURE that any particles from the thread chasing are at the Highest point ( easiest to vacuum out)...VS.... the piston at the bottom of the stroke...
......Mark
This^^^^^. When I was tuning cars for a living in the 80's and '90's, thread chasers saved the day many a time. The OP has IRON HEADS going by his engine description....have rarely seen a thread chaser fail with an iron head,as the issue is usually only one damaged thread, not an entire 'strip out', as we've seen with aluminum. So, follow Seeker's advice for the cheapest, least invasive, and easiest solution.
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Stripped Spark Plug Hole
… sorry; bad pun.
This. Surely the threads are just crossed up (unless aftermarket aluminum). Carefully try starting a thread chaser and see if that doesn't clean them up before going the helicoil route.
