That question should be pretty self-explanatory. Wife's '72 VW convertible just spit out a spark plug, and the threads are like Napoleon - they're history.

I've heard differing opinions of helicoils and timeserts over the years. What's the prevailing wisdom?

there is a debate about this? ...really?
I guess for a rookie with no skills, no talent and a shakey hand, the hell coil is better. ...and cheaper too

Actually, in my experience, the Time Sert is more forgiving, mostly because the cutter makes its own seat for the plug. The Cap'n

The tinesert is the only way to go. The helicoil does not have a sealing surface that will mate up against the spark plug. The tinesert is also permanent , the helicoil will likely come out every time you replace the spark plugs.

Used a spark plug thread repair kit on the heads from my 70 VW Bug and had no problems afterwards.

Timesert for me. Helicoils suck.

Timesert... only. Only do it once.

Helicoils are finicky. They are not designed for repeated use like a spark plug. They work well in soft materials for final assembly and for stuff that is not meant to come apart over and over.

The Time-Sert is the way to go. However make sure you use the countersink tool in the kit to ensure the top of the insert is below the surface of the head. If you don't the plug will lock against the insert and it will likely come out with the plug the next time you pull it, and with it the threads from the head.

Another consideration is that installing a heli-coil in a bore you can't see is a real PITA and could be downright impossible. Spark plug sized helicoils about have to use the pre-winder, which is large and cuimbersome. The Time-Sert is much easier to install in this application.

When using Time-Serts one thing to watch out for is that the top of the insert is not to large to fit in the countersink that you machine in the head. If it is then the time-sert will not seat into the head properly. (allowing the sparkplug to tighten against the insert instead of the head) I have had to file a lot of them down over the years to make them fit. Check this by seeing if the top of insert will fit into the counterbore prior to installing it.
Good luck!

Thanks for the feedback all. I knew one was superior to the other but it's been so long since I'd thought about it I couldn't recall. Just talked to my aircooled mechanic and he tells me he'll do a timesert for a half-hours' labor, so for that price I figure I'd rather pay him than mess with it myself.

a 3rd alternative. I stumbled upon this last week. I don't know if it is available in other sizes but it looks like a next gen thing....Watch the video to see how fast and easy it is. The tool was invented for the Ford Triton "spark plug blowing" engines. Ford wants to lift the body to make repairs i.e. new heads. This is done in car.

http://www.denlorstools.com/home/dt1/page_..._to_repair.html

I know at least one person who requests timecerts in all of his heads, stripped or not. He feels the risk of future damage is properly addressed by using these in old aluminum heads.

When I got my engine, one of the heads was helicoiled. It was a total bitch. It would pull out a thread or two each time I pulled the spark plugs - which was often when I was first trying to get the engine to run outside the car.

I finally had an insert installed and it has been golden for years now.

Zach

That looks like it's just a knock-off of a timesert.

I used to have that attitude toward the old plug threads in air-cooled heads. No more. Now I weld them all shut and machine new fresh threads. If the plugs are installed with a small amount of never seaze (I prefer Jet-Lube pure copper) and torqued properly the threads will never fail. No inserts to back out with the plug, or Heli-coils that sometimes wind in when the plug is installed. And if something does go wrong with the threads the owner can then install an insert, which is in IMHO, what they were designed for...field repair.