Hitchcocks Forum

I have an aluminium crankcase and a couple of valve covers that at one stage have been polished, or at least someone has tried. The result is anyway a too glossy finish, partly destroyed by later abuse.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

How can I restore the original finish? I guess the parts are die-cast, at least the finish on similar parts not messed with looks like that. A very nice, easy to keep finish that I would like to get back.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Would some sort of bead blasting do the trick?.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Regards, Anders F. R.

Watch this vidio too see the benifits of Vapour cleaning just copy & paste.

http://www.youtube.com/watch?v=r1cwHdwDOvU

Thanks! This looks definitely like the way to go! .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

One drawback only: It will be qiute expensive and a lot of paperwork sending my engine parts to England to get it done. I myst try and find someone that can do this in Norway, preferably in the Oslo area. .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Watching the video reminded me of that I also have a pair of aluminium cylinderheads that could benefit from this treatment, to say the least. Should I then do this before or after fitting new valve seats and guides? .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Before: No risk of damaging new seats and guides. After: Removing all traces of dirt that will come from the fitting of seats and guides. What's better? .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

But again: Thank you for shis very interesting information and a very quick reply! .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Regards, Anders F. R.

I thought that vapour cleaning will only clean away the dirt down to the surface of the metal. If the metal is polished beforehand, you will get clean, polished metal. It will not restore the original cast finish.

Hi Guys-------- if it helps any, I used exactly this same machine whilst at the MoD working on Aluminium and Dural items. It does exactly what you see it doing in the Vid. The blast element consists of very fine glass beads carried (in our case) in a water & de-greaser solution powered by 100 psi of air. It leaves a nice, clean, matt finish. If you listen to the commentary the shiny items have been polished afterwards. You can also have a dry-blast using the glass beads and air only. But you really must pre-clean otherwise any muck etc gets carried over into the system and clogs up. ANDERS }--If you take the head to a dedicated cyl head shop for all the work to be done they will remove all the old items----blast-clean---then re-build. This process DOES NOT REMOVE ANY BASE MATERIAL----only cleans back to original. My No1 Bullet Cyl. head had exactly this treatment last year whilst new guides etc were being fitted. Has just completed the 1,000 miles this week-end.

Sand blast kit for Karcher pressure washer, gives matt finish to alloy, cheap and easy to experiment with, try different sands and vary distance from object to change finish.

----------Nice one P.!!! Never knew they did that. ANDERS, have a look at this }---------www.ebay.co.uk/itm/PRESSURE-WASHER-SAND ... pt=UK_Home_------------------------

Pressure washer sand blasting does work. No need to use special sand, the kiln dryed stuff used for jointing block paving works well.

Thank you all for sharing ideas and links here! .-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

I am not sure that sandblasting is what I am looking for, even wet sand. I have seen a few sandblasted aluminium parts (cylinderheads, wheel hubs etc.) and they usually don't look good. The sand grains are to sharp and leaves the surface too coarse or rough (or how to describe it best). Nothing like the slightly rough but still smooth cast surface I want. Also, it very easily attracts dirt and is extremely difficult to keep clean.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

The thing with the vapour blasting mentioned by Paul M H is that they use fine glass beads that I suppose are round, not sharp. That makes a difference..-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

I will search for someone that can vapour blast my parts here in Norway first. If nothing comes out of that search, I will contact those vapour blasting pepole in Devon..-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-

Regards, Anders F. R.

Hi Anders
I have used this method for restoring the cast look to bruised castings which have taken on a shine when they have been rubbed. It is cheap. Take a sheet of coarse emery paper, place the abrasive side onto the casting and gently tap the emery paper into the surface with a light hammer. Try it on a small area to see if it works for you.
Regards
Edward