One of my spark plugs stripped and shot out. So, I out a Heilcoil down and put a new spark plug in. That one also shot out and stripped the Heilcoil. I'm assuming now that the head needs replaced, but is there any alternative to fixing or replacing a Heilcoil?
(On a 2001 Ford F150, 4.6L)
Yes, but it gets really expensive.
The damaged area is completely bored out, the item is heated, a slightly oversize plug of the same material is machined and frozen in LN2, at the peak moment the plug is forced into the bored hole with a hydraulic press and the item is left to cool.
Surface is machined as needed, new hole is drilled and tapped.
Entire process cannot be performed in all cases, because on 4.6L and 5.4L heads at least 2 spark plug holes don't have enough room or material available for removal.
It's also a 1-2 day job, done in a well-equipped CNC machine shop with large ovens and liquid nitrogen capabilities.
I've seen it done several times on some impossible-to-replace cobra heads, and when done well, the strength numbers show it to be a permanent fix, virtually as strong as contiguous material.
Cost: About the same as getting a complete top kit from Edelbrock, just under $3,000.00
I think you can see if you have access to exact-replacement salvaged heads, it's a lot less costly to use those.
LOL
Never use a Helicoil for anything important. Always use a Timesert insert that locks in position and is a permanent fix. Helicoils are just wound up springs that don't last.
