Restoring Original Plugs

30blutudor

30blutudor

Senior Member
Does anyone know of any publications or articles pertaining to restoring original 3X spark plugs? There was a post on here a while back which explained the differences in years and lightly touched on some things, but I am looking for more information like how to properly clean porcelain without damaging it. What method is the best for cleaning the rust from the base(acid,sand blast bead blast etc.). Also interested in the blueing process. Can this be performed successfully with the kits available from the firearm catalogs or does it have to be profesisonally done? If so who does it? With the value of the plugs as high as it is I want to do this right the first time.
 
A nice restoration article is in the Jan/Feb 1996 MARC Model "A" News, pg 8-9. The bottom of the porcelain core may be LIGHTLY blasted or cleaned with a fine steel brush or steel wool. Do not use chemicals or solvents on the upper portion as they may damage the porcelain or printing. Be careful of the copper gaskets. They are special and to my knowledge are not reproduced. The steel plug base and lock can be bead blasted then parkerized or blued. Bluing kits are available at any gunshop. I just parkerized a set and the bases closely resembled several NOS plugs. Follow the parkerizing solution heating instructions and quench in dirty motor oil. It is not a hard process and you will be pleased with the results. Highly recommend you read the article.
 
I woudn't use a wire buffing wheel to clean the porcelain or the brass tip. Use a brass cleaner for the top. Arcing can occur down/up the porcelain if you use a wire buffing wheel. Possibly try a very fine abrasive wheel, or mask off the top section and use low pressure glass peenex blasting. Emphasis on low pressure !
 
I tried cleaning a modernish plug that had some protruding porcelain with a little steel wire brush once...I immediately saw gray steel tracks on the porcelain everywhere the brush had traveled. I discarded the plug without testing, but have to assume that using it would have been hopeless. Never tried a brass brush and would not on a plug I meant to use...the porcelain is hard and abrasive.
I never saw tracks when using thin steel tools to poke and pick at carbon, probably a combination of no wiping type contact and harder steel in tools??

I once corresponded a bit with a HAMBer whose father had run a sparkplug rebuilding plant...commercially "rebuilt" plugs were commonly sold back when, both early take-aparts and modern ones. Last saw them in a store (in a very poor Appalachian area) in the 1960's.
Part of the process was cutting off the original side electrode and then welding (Resistance welding, I think) a new one on after everything was clean, allowing a bit more adjustability to meet the slightly shortened center one. There might be something in that of use to a modern day rebuilder.
 
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