From: H W Jones [email protected]
Date: 8/05/00
Time: 19:43:04
Remote Name: 147.188.55.6
As i understood it Colin Chapman de-siamesed the inlet ports by adding two tounge like pieces of metal into the inlet ports on the austin cylinder block, thus producing in effect two ports out of one siamesed port, hence the term de-siamesing them. As the 750mc rules at the time forbade any modification of this sort to the block, Chapman attached these tounges to the manifold, thereby not breaking the rules. Also as the ports were now of smaller volume Chapman ground out the ports first to compensate. This is a far simpler method of de-siamesing an Austin block, all you need is a block with thick metal in the ports and to be good with a file. The method stated by the two previous replys seems to be not de-siamesing but a reversal of the ports. The fact that there would be only two exaust ports seems to be far from ideal. But i do not know if Chapman ever did this.