Gutting a spark plug

[Walt Fricke]

I want to make a couple of tools to make compression and leakdown tests easier by making metal tube extensions, with air chuck fittings on the outside end. I have lots of old spark plugs, so that seemed a logical way to get the thread needed for the inner end of things.

Easy to break off the top ceramic, and the bottom piece also. But my plans to punch or chip out the ceramic in the center have come to naught.

Any suggestions on how to bust this out?

I suppose I could purchase a bolt with the right thread, and drill it out. Whatever I use is going to be welded to the end of a tube anyway. But a plug seems so right, and it will seal.

[snbush67]

I have no idea how to punch out the ceramic, but aircraft spruce sells these extenders with a t handle, I've always wanted to order one but haven't yet.

Compression from Aircraft Spruce

[manbridge 74]

Grind crimp and ground strap off with dremel/cut-off wheel and push center out into socket with vise.

[Walt Fricke]

Ah - the crimp is the area just above the hex? Perfect. Thanks

[sc_rufctr]

I tried the same thing some time ago. The ones I was gutting were soft... Very difficult to weld without burning them. (MIG)

[Charles Freeborn]

Originally Posted by sc_rufctr

I tried the same thing some time ago. The ones I was gutting were soft... Very difficult to weld without burning them. (MIG)

I've built adapted plugs over the years - mostly for motorcycle purposes. Brazing is better than MIG welding - lower temp, plenty of strength.
-C

[Trackrash]

I made this one many years ago. Brazed 1/4" pipe onto the plug.

[Walt Fricke]

Gordon - Thanks.

We both had the same idea (as did many, including Aircraft Spruce).

Good to know that my MIG may not work. My skills are a bit rudimentary. I've not had a lot of luck brazing, though. I've got rod and paste, and an acetylene torch, but I have never been able to get it to flow like solder.

I've got to be careful about length - the #6 is a bit cramped on the outside, especially since I have two AN8 lines and a fitting back there for my IROC spoiler mounted transmission cooler.

Your picture gives me an idea, though. I think the "handles" on the ACS photos might get in the way, but if I have (or acquire) a ratcheting wrench the size to fit the air fitting, if I size it right I can use that to snug the gizmo down, or when the plug threads get gummy from anti-seize.

[tabasco]

Check this out :
https://grassrootsmotorsports.com/forum/tech-tips/making-a-spark-plug-thread-adapterr/75335/page1/