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Well i figure do it once do it well so i'm not skimping on anything (i'm not spending money when i don't need to, either).Originally Posted by Jarred
You know when you get a cheap injection moulded plastic part and there's little feathery bits hanging off it in spots? That's called flash. Its where the to mating halves of the mould (or sliding cores etc, but we'll keep it simple) don't seal together properly and the plastic 'squirts' out a little between the faces of the mould.
The same goes (basically) for a casting or forging. Where there are mating faces the can be flashing if the cast or forge die isn't perfect. In the cast it happens for a slightly different reason but we'll leave it alone because this thread isn't the place to be explaining the casting, forging and injection moulding process in detail.
Where you have flash, it can cause a weak spot and cracks/ failures always start from imperfections. Always. That's why you see Top Fuel engine rods are polished. So that there is nowhere for a failure to start, although that's not to say something will never fail.
So, by de-flashing the block and your rods, you eliminate a potential failure point.
The VW castings are very high quality, and the only spot on my block that needed de-flashing was the main bearing webs. The rest of the casting is perfect. Same goes for the rods, VW rods are very high quality and very minimal de-flashing is required, followed by shot peening.
Shot peening is basically sand blasting the rod. It uses glass beads. These glass beads remove the 'skin' of the metal and remove any surface stress and tension within the rod, making it tougher and less brittle.
Clear some things up?
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