Planning the next
AO Silver Member
Join Date: May 2007
Location: United Kingdom
Unfortunately I've been a bit remiss on this project and didn't take photographs. Apologies.
What I did was -
Gave both parts a really good wash in degreaser. Unless you want to disassemble the breather port ducting inside the cam cover ( I didn't ), get lots of degreaser in there to get all the manky oil out.
Plug the three open areas of the breather port ( outside, the small hole inside and the slot inside ) with paper tissue and cover with gaffer/duct tape as appropriate. If you disassemble, this is not so critical.
Protect the gasket surface of the cam cover with the old gasket taped in place. Protect the oil filler cap machined surface ( I used a spare oil filler cap which I covered in gaffer tape so it didn't itself get damaged by the next step ).
Grit blast the outside surfaces. This will get rid of the ingrained crud and provide a nice key surface for the black ( in my case ) paint.
Unplug the ports and ensure no grit got into the breather port. Be very, very careful no grit is left in any part that oil can get to. Use more degreaser and water to be sure.
This is where it gets nasty!
I used a delta sander on all the accessible surfaces to be polished with a 60 grit paper. You'll probably go through quite a few of these delta sanding sheets ( screwfix do nice cheap ones! ) as they're not really intended for aluminium. Work the delta sander to remove the casting imperfections. Once it's looking acceptable, work your way up in grit sizes to 240. Be careful not to give the rounded surfaces e.g. the dummy spark plug lumps flat spots.
Once up to 240 grit with the delta sander, start on the wet dry paper ( screwfix again ). I started with 120 grit W&D and eventually moved through 240, 600 and 1200. Unfortunately screwfix don't seem to do wet & dry over 1200. Use plenty of water to lubricate the paper and carry away the aluminium. Your hands will get filthy even if you wear gloves as the gloves will split. You will have difficulty with the curved edges and the flat surface around the oil filler cap. No alternative other than making your fingers hurt. When sanding the ridges, use a sanding block to get the top surface flat and to get an even sanding over adjacent ridges. Be careful not to sand the lettering. You need to keep nice sharp edges for the later painting.
Eventually, you'll get an acceptable sanded finish at 1200(+) grit to start polishing. I used a combination of 150mm wheels on a bench grinder, 75mm wheels in a drill and various types of felt pads in a dremel to do the fine corners. In my case, I'd start polishing and find an imperfection and have to go back to the wet&dry ( or even the coarse papers on the delta sander ) and start again in those patches. This aluminium is not the highest quality and the die casting isn't great in places. I started with coarse brown polishing compound finished with fine ( blue ). I also used Autosol with the dremel as it is quite aggressive and quickly got a reasonable finish where I couldn't get sandpaper to do it's thing properly. Once the autosol got the surface acceptable, I then went to the brown & blue polish in the dremel.
You'll need chalk to remove the residual polishing compound from the aluminium.
Once you have a good polished surface, mask off as much as possible and paint those bits that need to be painted. The top of the aluminium ridges will get painted and they will have to be carefully cleaned up of paint and touched up with a felt pad in the dremel.
The lettering was painted by hand with a very fine modelling paintbrush.
Once all the painting is complete and dry, go over the polished bits again with the softest buffing wheel and then clean it with chalk.
There are loads of videos on Youtube about aluminium polishing.
Oh, and this is relatively high maintenance. You'll probably need to freshen the polishing every year or so owing to oxidation and general engine bay crud.
I'm also going to clean the bolts and give them a new bright zinc plating. I don't want manky bolts letting it down!
Last edited by pkr; 22-04-15 at 17:29.