The best and safest way is carbon dioxide ice blasting , expensive but very safe as there are no glass beads or water as the ice simply changes to gas

email (option): warbikes@gmail.com

['The best and safest way is carbon dioxide ice blasting , expensive but very safe as there are no glass beads or water as the ice simply changes to gas..']
I've never seen that process advertised anywhere personally...

Anyway, I've built scores of engines since the 1970s and spent nearly 18 years doing that exclusively for a living..The vast majority of those engines apart from a few in the early days had the major castings either bead blasted or vapour blasted...For the last 30 years I've done them myself in the blasting machine I built for the job...I'd recommend removing all components and fixed fittings from the castings before commencement...

Personally, I consider that method or something similar to be the only way to thoroughly clean the castings to an 'as new' finish and I've tried many of the other methods suggested...Of course if you want 'patina' other methods will suffice but I prefer the ex factory look as did the majority of my customers...

I would suggest problems resulting from using a blasting process are caused either by inadequate preparation before blasting or inadequate post blast cleaning of the components...

I'm happy to consider the fact that in 18 years of building BSA single engines commercially, both standard and tuned units I only ever experienced two engine failures, both of which were unrelated to the blasting processes I used. So, there are alternatives but there is no inherent risk in blasting if carried out correctly...Ian

email (option): ian@wright52.plus.com

Thanks everyone for your input.

Just for clarity, when I say I want to Vapour Blast my cases, I mean, I want to pay a professional to do it, not DIY.

Of course, I will clean the casings of all oil and paint before sending them off. Casings only no parts left attached.

The bushings need to come out and new ones put in as some have seen better days and if I don't want issues after restoration, the best is replace everything... bearings and bushings.

I have sourced a company to vapour blast for me and will start ordering bushings and bearings first, before I start removing them before sending off for blasting.

That bush with the punch marks around it will probably be a bad fit into its housing...It may be you'll need a custom bush for that one to get the fit right...I'd get it out and determine what's going on before ordering a standard replacement for it...Ian

email (option): ian@wright52.plus.com

The cam followers should be removed also. Often not easy! Ron

email (option): ronpier@talk21.com

Anything like a bush or a bearing that I would be replacing, I'd leave in place to protect the housing. Blast finishing can make them oversize.

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With the correct grade and type of media and the right operating pressures components are dimensionally unaffected and threads, bearing housings etc. are not damaged...Obviously an unsuitable, coarse media applied at high pressures could detrimentally affect surface finish and dimensions..We've all heard the stories of castings that end up looking like they've been shot peened...However, a suitable media for blasting rusted iron barrels for example wouldn't be selected for aluminium components...

For some items a two stage method would be used...It's a common misconception that in all cases blasting is an aggressive method of surface finishing when in fact glass, plastics and many other materials can be treated in this way without damage to the surfaces...Ian

email (option): ian@wright52.plus.com