vikebo Posted June 12, 2007 Share Posted June 12, 2007 Hi, My Seven died suddently a few days ago while driving slowly downhill. No signs before the engine just stopped. It has a Lotus Twin Cam with an Aldon Ignitor and an electric fuel pump (and the pressure seems ok). The battery voltage is approx. 12.5 Volts, and I can measure it on the low voltage side of the coil (Lucas, but unsure which). The resistance from the 12 V terminal of the coil to the GND terminal is 3-4 Ohms while the resistance from the high voltage terminal to chassis is approx. 6-7000 Ohms. I have measured the signal from the Aldon unit with an oscilloscope, and is gives a square wave signal, so I guess it is ok. All the high voltage leads are 2-3 years old from Magnecore and looks fine. The resistance from the coil end to the center tap of the distributor cap and also from each of the spark plug connectors to the different terminals inside the cap are 3-4 kOhms. My timing lamp (and also another one I tried) does not flash on any of the plug leads or the high voltage coil lead. When I connect the plug leads to a spare spark plug there is no spark, but if I connect the coil lead to a spark plug I do get sparks... To me, it seems like there is a problem with the distributor cap or the rotor. The rotor and the center tap seems fine, the contacts in the lid are slightly pitted, but not bad. I also find it strange that it stopped so suddently and will not fire at all if it is the cap. Any ideas? Eivind Link to comment Share on other sites More sharing options...
Martyn Heesom Posted June 13, 2007 Share Posted June 13, 2007 Have you checked the contact under the central terminal on the distributor cap - there should be a spring-loaded carbon contact that presses down onto the centre of the rotor arm. Lotus twin cams were originally fitted with a rev-limiting rotor arm - if your car has one, check that this has not failed. Edited by - Martyn Heesom on 13 Jun 2007 08:38:18 Link to comment Share on other sites More sharing options...
vikebo Posted June 13, 2007 Author Share Posted June 13, 2007 Martyn, thank you for your reply. The center tap was fine, but I got a suggestion from a car mechanic I know, and he was right. The sparks were arching through the rotor. It is probably cracked internally even though it is quite new. Luckily I had an old one which I could try, and now the engine starts. Eivind Link to comment Share on other sites More sharing options...
JampJ Posted June 14, 2007 Share Posted June 14, 2007 Problems with rotor arms on this type of distributor is very common. Always carry a spare! Cheers J&J JFDI (Just F*****g Do It) Link to comment Share on other sites More sharing options...
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