Helicoils in Aluminium heads
Helicoils in Aluminium heads
(OP)
I have stripped the thread in a 1969 VW Beetle spark plug socket and can get from my local car parts store some 14mm aliminium coils (similar to "Helicoils"). I'm a little suspicious, though, as they seem to be fairly low grade aluminium. If they in turn strip out, then the head becomes useless. I have read that installing Stainless steel is a better option, though the dissimilar metals may release under high temperature... Am I being too fussy? Would the Aluminium ones do? The advice on the packet is to "Locktite" them in. Would that hold up umder load?





RE: Helicoils in Aluminium heads
The aluminum heads stripped out vewry easily, and I never had another problem once I put in stainless heli-coils. If one plug hole went, I usually put heli-coils in both while I had the tools out.
I don't understand where the helicoils could release to.
I think that aluminum, to a stainless helicoil, to a steel spark plug is a much better combination than aluminum to the steel spark plug. That combination has failed many times, hence the development of heli-coils.
yours
RE: Helicoils in Aluminium heads
RE: Helicoils in Aluminium heads
RE: Helicoils in Aluminium heads
I hot rodded air cooled VWs for years, and repaired more than one damaged thread.
Because the VW plug is a short thread, the helicoil must be the full length of the thread. It is then subject a small piece of the thread in the head failing and a small piece of the helicoil unspringing from head and changing the thread pitch for that portion.
The sleeve insert is solid and cannot "spring out" in this
fashion.
If you cannot buy them, a good machinist should be able to make them.
I would expect a good place to start looking for them would be H&M Ferman in Peakhurst in Sydney Australia.
I can get a phone number if you need it.
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Helicoils in Aluminium heads
A liitle closer to home, "Re-coil" in Aus do re-threading kits, including 14mm spark plug sets, but they might only be the wire wound type.
Use the solid ones, and measure so they don't overhang into the chamber.
John.
RE: Helicoils in Aluminium heads
www.timesert.com
RE: Helicoils in Aluminium heads
RE: Helicoils in Aluminium heads
I wouldn't worry too much about reliability. Way back when, anyone who built VW's replaced the S/P threads automatically, even on brand new heads. Any good hardware or autoparts store used to sell inserts for them.
RE: Helicoils in Aluminium heads
Run the engine hard once after installing the insert, see if there are significant differences between the modified and non-modified cylinders. It's conceivable you'd need to go one heat range colder in the re-threaded cylinder.
RE: Helicoils in Aluminium heads
Regards
eng-tips, by professional engineers for professional engineers
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.
RE: Helicoils in Aluminium heads
They are much better than the solid inserts. Use white
grease on the tap, it will catch the chips and you don't
have to pull the head or engine.
The more you know, the more you
know you don't know....