acbateman Posted February 28, 2003 Share Posted February 28, 2003 Can anyone help with this please? We have a 1991 1700 x-flow with standard jetting, new needle jets, correctly adjusted float heights [i think] and recently cleaned K&Ns. However, the front two plugs are ALWAYS darker [ie quite black and prone to fouling] than the rear two, despite having the idle jets set up etc on a rolling road. Should I be considering anything else to do or is this fairly normal for a x-flow [rebuilt by Caterham 5000 miles ago]? Link to comment Share on other sites More sharing options...
TomBerlin Posted March 1, 2003 Share Posted March 1, 2003 AC, There are two things you can do to start with. First, find someone with a CO capable exhaust gas machine and make sure it's actually running rich. You can adjust the idle mixture screws one at a time and see how much fuel is being used. Second, make sure the problem is not something like valve clearance or compression. Also check for air leaks @ the manifold. Just some thoughts. Tom Link to comment Share on other sites More sharing options...
Graham Sewell Posted March 1, 2003 Share Posted March 1, 2003 First reaction is to ensure that the two carbs are balanced - this is a fairly classic symmptom and the carbs can go out of balance in 500 miles - or may last a lot longer. Get the proper synchrometer and the job takes 2 minutes. Low tech luddite - xflow and proud! Link to comment Share on other sites More sharing options...
acbateman Posted March 1, 2003 Author Share Posted March 1, 2003 Thanks for your comments. As far as I know, the valve clearances are fine and the carbs are well balanced. The throttle response is certainly crisp and the car runs v well - it's a bit of a mystery! Link to comment Share on other sites More sharing options...
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