Warning: Corvair content! Corvair heads mount to 10" long tapered thread studs that thread into the aluminum case. The threads at the other end were bad on mine, so I removed them for replacement. No material came out with any of them and the threads looked good in all 6. I replaced all 6 with standard-size studs and red loc***e. 3 tightened down, 3 did not. In other words, I kept tightening util the studs reached the bottom without getting more "difficult" or reaching torque, even after the Loc***e set up. I changed studs around in case some were odd sizes, but got the same results. So, I got 3 .003 oversize studs (the next size up). I started threading one into the "worst" hole and it threaded about 1/3 of the way in and I couldn't tighten it anymore (the stud was twisting a little, but not turning in the hole and it was really tight). I backed it out and cleaned off the Loc***e. Since the standard size is slightly too small, and the next size up is too large, I was thinking I could use a little Rocksett glue. It's good to over 2000* and designed for use in threads. Good idea/bad idea? Here are the details of Rocksett: Rocksett is an all-purpose engineering adhesive/coating for use in threads and cylindrical ***emblies which require to operate at high temperatures. Product Benefits single component withstands temperatures up to 1100° c non toxic non hazardous solvent resistant acid resistant Cured Properties of Rocksett Tensile Strength 1.5 N/mm2 or MPa (230 psi) Shear strength 3.0 N/mm2 or MPa (460 psi) Temperature Range -180 + 1100°c (-292 to 2012*f) Gap filling >.15mm Electrical insulation up to 20 radio MHz
It's been a while, but don't they make some inserts called "Case Savers", or something like that, (from my V W days), maybe something in the thread pitch you need. I'm thinking that adhesive is bad *** stuff, but may not stand up well to the expansion and contraction going on around it......
The absolute best, only way to go is to use Heli-Coils or the equivalent. The WWII patent has run out and there are other company selling helical inserts but believe me this is the way to go, why trash a case or do a bogus short term repair when you can fix it once and forget about it. The reason you want to start with heli coils first rather than case savers or solid inserts is that the solid insets are often a larger OD so you still have an option to use them if some of holes are too ******ed up for a heli coil. If you start out with the bigger insert....well you just lost an alternative if that gets screwed up and things can get real difficult when you have a .750 hole and a .500 fastener. Anything can be repaired, I have done some pretty elaborate repairs over the past 35 years to get a hole repaired....but it will get pretty pricey if you have to pay someone to do the aforementioned elaborate repairs.
Actually, Helicoils are notoriously bad in the Corvair world. Case Savers are preferred. Either way, you need 2 different size coils since the stud requires a taperd hole. It's usually considered a last ditch effort. That's why they make 2 different size oversize studs. Usually if you experience what I did with the standard studs, it's recommended that you go with the .003 studs... but I can't get that in. I'm somewhere between standard and the next size up. Most of the Corvair guys say the Loc***e SHOULD be sufficient. It's not. That's why I was thinking about the glue... and I already have a bottle.
Either use heli-coils or Time-Serts. Each has a specific application. I've used Heli-coils in blocks and Time-serts in intake manifolds and heads. I personally like the Time-serts if you have enough wall thickness.
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