A mini-update, to allow you guys to offer sage advice before I go too far...
Cleaning the engine parts without a blast cabinet is actually not too bad. I have done the head cover and most of the barrel already. I reckon by the time I have finished, it will be about the same effort needed to do the brakes.
So here's where we started: most paint has already flaked off but some still stubbornly hanging on, and loads of corrosion patches and staining.
The method that seems to work best is to apply paint stripper to the paint patches, wait 20 minutes and hit with a brass wire brush on the Dremel. Then pressure wash. Then put it in the sink and rub it with wire wool and/or the brash brush again. Rinse and repeat. I have done two cycles so far and nearly done - however I did try other things like a green scourer but they didn't seem to do much.
Here is the head cover which is now ready for painting. I also hit this with phosphric/hyrdocholic acid after taping over the camshaft journals. I am not convinced it did very much though, as I had already removed all of the corrosion via mechanical scrubbing. Maybe it will make a better surface for the paint? ...who knows. I am not going to use it on the barrel or head, as I am worried that it might etch something it shouldn't...
You can't tell that it hasn't been blasted can you?
That's because of my secret weapon. An el cheapo sandblasting gun and 5kg of aluminium oxide from eBay. Oh, and a piece of tarp (an unused car boot liner) to catch the media of re-use. I think I used 1/4 cup of media to just puff into those nooks and crannies that I couldn't get to with a wire bruch. I wouldn't want to do the whole thing without a blast cabinet, but for touching up those hard to reach places its a great cheap tool (...as the actress said to the bishop...).
In case it needs stating: DON'T USE SAND. Google 'silicosis' if you need convincing. Always wear a respirator. Don't fuck about with your lungs.
In other news, it's worth checking that your head cover is a matched pair with the head. This is because the camshaft journals are machined with both parts bolted together. Use a mis-matched pair and the machining won't match up and you'll have problems [Edit: this statement may be BS, see scottieh's post below]. I have three engines in pieces so needed to check I had the pair matching pair.
You can check by looking at the IDs scratched ('cos they are) into the inside of the cover and on the head. See the pic.
I'm constantly amazed at dickheads on eBay selling one half of a crankcase - useless without it's matching other half. You can also find the same sort of IDs on the two crankcase halves.
The paint stripper I'm using is Paramose, and it works brilliantly. I wear a full-face respirator though. If you catch a whiff of it you know about it, and it also stings the eyes. Not to be messed with.
Works wonders getting carbon off a piston! I have a 'spare' piston and tried this and also phosphoric acid/hydrocholic acid - both work but the acid definately etches the surface while the paint stripper does not.
I'm also stripping the side covers back to bare ally. Some dickhead painted the clutch cover, including the inside edge that mates with the crankcase. So, it's all coming off and being repainted.
