Webber carb on SC running Rich question
 

Hi Just got my SC ROW car back from a dyno run and have found it running Rich between 2500 to 4000 rpm up top it is perfect down low it is also good .
what can be done to lean it out between 2500 and 4000rpm ?
Thanks John

Hi John,

Perhaps you could share some more info regarding your engine and jetting such as: Weber identification (IDA, IDAP, IDTP, etc); exhaust system details (early style headers, twin pipe Dansk, etc.); main venturi size; idle jet size; emulsion tube type and main air correction jet size.

The region you are rich is is the "transition-range" and is affected by both the end of the progression circuit operation and the beginning of the main circuit operation. The change could be as easy as installing an emulsion tube or as complicated as changing all the brass jets in your Webers.

I would say there is very little use for full throttle below 3500 RPM, so don't worry about that region. You want to get it right from 3500 to redline during WOT operation. I haven't found ways to make the mixture curve change but you can move the entire curve up or down. You might want to run a little leaner overall. For the low RPM stuff all you care about is mixture at cruise power settings. For that you'll need to find the right idle circuit jets and adjust the air bypass screws.

-Andy