Time Serts and Helicoils are substantially different, in that Time Serts install a FULL depth thread in the other part. Helicoils cut only a partial depth thread and thus do not restore the original strength to the part.
The down side of Time Serts is that one needs more material in the parent part to install them, thus they may not fit in all applications where the thread is close to the edge of the part.
No, I don't know where to get Time Serts, but I have seen them in Kent Moor kits for GM applications. In that form they are very expensive.
Mcmaster-carr has them and is located in LA. type "threaded insert" in their search then click "self locking". Otherwise try an automotive machine shop or maybe an aircooled VW specialist.
you stripped out a headbolt on a 22r?
I've seen the thread inserts you're talking about sold under the name of "Keen-serts". I'd think that places like Napa, Carquest, and certain local suppliers should at least be able to order them.
But, personally- I'd just use a helicoil. I LIKE keen-serts better (they're easier to use, but hard to find)... but helicoils are much easier to find and will do the job just as well- you just have to exercise more caution when installing them. I'm gonna have to disagree with a previous poster who said that helicoils don't restore the original thread strength- if properly installed, a helicoil is actually stronger than the original threads. Also, in cases like yours where longer thread engagement is needed, I've stacked two helicoils in the same hole- one right on top of the other. Works fine. If there isn't room for two helicoil inserts in the hole, you can cut one to length (this requires special care when measuring and cutting, but I've been successful at this several times, including head bolt holes).
Regardless of which thread insert you use, be sure to put locktite on the outer threads of the thread insert- nothing [censored] me off like pulling out a thread insert along with a bolt. Also, liberally oil the inner threads of the insert and the bolt threads so that they won't stick (actually, I usually use antisieze for this... but that probably wouldn't be a good idea for a head bolt. And be sure to install the thread insert (whichever type you use) slightly below flush (one thread or so).
And IF you go with the helicoil option, use a drill bit that is 1/64 smaller than what they reccommend. I can tell you from experience that if you wobble the drill AT ALL using the reccommended bit, then the insert won't have adequate thread engagement. The slightly smaller bit will allow for fuller engagement between the thread insert and the block- and help compensate for drill wobble (which WILL happen unless you can mount that block on a drill press or unless you have a magnetic base drill handy... both of which seem unlikely). If you have trouble starting the tap, then you can enlarge just the first 1/8" to 1/4" of the hole with the recommended size bit.
"I've seen the thread inserts you're talking about sold under the name of "Keen-serts". I'd think that places like Napa, Carquest, and certain local suppliers should at least be able to order them."
Absolutely correct, try you local NAPA. Installed correctly, a Keen-sert will be stronger than the original metal.
From the research I've done, Time-Sert seems to be the best in thread replacement kits. At least better than Helicoil. I did an Internet search, and found a couple of suppliers that caried them. Then I found a local company that carried the line, and they beat the Internet prices even with tax. The M14x1.5 kit I picked up is a quality tool.
The place in Vegas that carries them is McFadden-Dale Industrial Hardware. I'll bet there are similar places in LA.
Mcmaster p/n 90245A169 would work great if you have enough material in the block to drill it for a 16mm threaded hole. a Heli-coil (p/n 91732A964) will require a smaller hole and will be strong enough for a head bolt.
The thread insert in this picture: http://www.mcmaster.com/#metric-threaded-inserts/=1c1kn4
That setup with the 'key locks' is like the Keen-sert design that I've used before. They work great, are easy to install, and use a standard tap (as opposed to a specific helicoil tap). The only drawbacks are that they're kinda hard to find, and you have to drill out quite a bit more metal than you would with a helicoil. Also, there's a special tool used to drive those key locks in place- but you could probably get by with a socket or something if you're careful. Oh, and those kits are pretty [censored] expensive.
I still recommend helicoils: cheap, readily available, and more than adequate. Like me.