oneaves2005 Posted August 26, 2015 Share Posted August 26, 2015 Hi All, I have recently built a few V8 race engines. One of the engines was for our car and the other two for customers, our car was very rich in the midrange on the rolling road but perfect at top end. On track the midrange pickup is sluggish compared to the other two engines which are identical with the exception of carbs - they both run weber 48's. I though that Dellorto's were supposed to atomise the fuel better giving a better midrange performance! I need to investigate choke sizes to make sure they are not too big, I know relatively little about carbs - My question, is there anything else I can do to weaken off the midrange without weakening the top end? Cheers Ollie Link to comment Share on other sites More sharing options...
DaveNotSoSideways Posted August 26, 2015 Share Posted August 26, 2015 The emulsion tubes are probably wrong. If it left the rolling road rich in the middle they didnt do their job correctly. Probably didnt have any tubes and sent you on your way knowing they'd done a half arsed job. Link to comment Share on other sites More sharing options...
oneaves2005 Posted August 27, 2015 Author Share Posted August 27, 2015 It seems none of the rolling roads stock any dellorto parts... How would the emulsion tubes effect just midrange? Link to comment Share on other sites More sharing options...
DaveNotSoSideways Posted August 27, 2015 Share Posted August 27, 2015 Cause the emulsion tubes control when/how much fuel is delivered in the mid range, when the main jet fires on, how effective the air jet is in relation to main jet size and they control how the auxillary venturi talks to the main jet stack. You need a tube with more holes or thicker o/d to lean it out then increase main jet and decrease air jet etc. The emulsion tubes are the most vital part of the jetting, any monkey can change main jets and air jets but the tubes are usually overlooked somewhat. Link to comment Share on other sites More sharing options...
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