RB25 conversion Stage 3 - Strip RB25 ready for boring, and clean the cylinder head

A couple of weekends ago I removed the head from my supposedly 'good' RB25 to discover a badly detonated piston in number 6 cylinder.

I decided to buy some 87mm forged pistons and get the block bored to remove the surface damage the detonated piston had made. While waiting for the pistons to be delivered, I spent this weekend stripping the engine down to a bare block so it's ready to go to the engineers for boring as soon as the new pistons arrive.

Here's number 6 piston - you can really see the extent of the damage now it's out of the block...

I gave the rest of the pistons a close visual inspection once they were removed from the block and noticed a couple of hairline cracks on the ringland of number 4 piston. I picked at one of the cracks with a small screwdriver and a piece of the piston ringland came away. Good thing I decided to replace all the pistons instead of just number 6 then! Here's a couple of pics...






It was interesting to see the engine apart, particularly the oil pump and crank interface. I've read about people fitting crank collars on to their crank shafts in order to lengthen the surface area the crank extends into the oil pump drive. Having seen first-hand the length of crank that actually engages the oil pump drive I'm thinking of researching getting one of these fitted myself. You can see in the below pics the marks where the crank and the oil pump meet...





Once the block was all apart and ready to go I spent another good few hours cleaning and polishing various parts of the head and block. I removed the paper gasket remnants left by removing the oil pump and oil filter assembly with a razor blade, and then finsihed off with fine wet and dry paper and steel wool. I also cleaned the block (both head and sump sides), and the inside of the head. The cylinder head has pitting on number 6 cylinder where detonation has occured. I cleaned up the area as best as I could in order to assess the damage. All the damage looks like it can be removed with some sanding, so I will be having a go at that area next weekend. It's important that there aren't any sharp edges in the combustion chambers otherwise heat-spots will occur when the engine is put back together and is running.

Here's some pics of my hard work...










And that's it! Next installment will be all about some very shiny new pistons :oD