From: Barry Lovelock
Date: 07 Dec 2000
Remote Name: 18.104.22.168
I think the comments about low compression ratios and moderate tuning are probably true and bear in mind that these engines originally ran on a very poor quality unleaded. The recommended valve adjustment period may have been some reflection on the wear rate though! The "A" series engine was chosen for the tests because it was the worse one for valve seat recession (VSR), in fact, the rate of wear over the period was much more than the initial valve clearance settings! An MG Metro Turbo on a motorway, used regularly, probably being the worst-case scenario, however unlikely nowadays. In the (really) old car fraternity, the biggest problem so far seems to be overheating and poor starting, whether or not unleaded or LRP is used - witness some Veterans totally refusing to re-start when hot. I suspect the biggest VSR will be suffered by those of us who drive 50's/70's classics, hard, such as I do my RS2000, but that is easy to buy a hardened-seat head for. Just to go back to the "A" series engine and this is a true story, I remember going to the "chippy" in a highly tuned Cooper "S" back in the 70's and finding it still running-on when we got back to where it was parked - on the double yellow of course!! The "Heron" head, with it's pinch combustion chamber design produced this hot spot which glowed like a spark plug.
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