Weber tuning

[acbateman]

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]?

 

 

[TomBerlin]

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

[Graham Sewell]

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!

[acbateman]

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!