Originally Posted by
Glowgeek
Thanks John.
I asked Time Fasteners why they didn't make a 1/4-32 Bigsert. They said that the standard Timeserts work so well that there wasn't a high enough demand to justify the tooling cost. They also claim that a properly installed standard insert should outlast the life expectancy of an engine. Makes sense, the torque requirement is very low on glow plugs and they are infrequently removed.
I will be forced to use hi temp/hi strength loctite to capture a custom fabricated brass insert because there will be no locking feature, other than tightening the shouldered insert into place. Will loctite survive the temps experienced at the spark plug? Hmmmm
I like the permatex red "high temp" thread locker, is good for 450F... cylinder casting temps under normal operating conditions shouldn't reach anywhere near 400F... I would be surprised to see an air cooled model 4 stroke go above 300-350F... VW engines, #3 cylinder would reach 380F, and if the oil cooler was blocked with caked on oil&dirt could go above 400F, but those are very different running conditions in comparison, with shrouded cylinders and poor air flow around the engine.
The time-serts have a serrated edge that gets swaged into the base metal to prevent the insert from backing out, but they are also set in red loc-tite as well... I wouldn't be too concerned, just clean / decrease both the cylinder, and insert threads, and then when you assemble it, tighten the insert firmly, and then let the thread locker setup at least 48 hours before you run the engine. You can also take a fine point center punch and peen the edge of the brass insert into the base metal in 3 locations, to capture the insert.
https://www.permatex.com/products/th...cker-red-6-ml/