twin 40s

kemo

Torque Junkie
Points
292
Location
Northampton
Car
Ford Sierra 2000E
hi all
has any body got any info on how to balance a set of 40s on a mk2 2000rs
any help will be good
 
i think the original spec called for 44 idf webers you need to check what they are should be stamped 44 idf 40/41 on both carbs . if they are amatched set you are laughing if not you need to check all jets etc are the same size . there is tonnes of info on sizing /jetting , its a guide only but will get you started .std specs ase follows
choke 34 mm venturi 4.5 main jet 1.45 idle jet 0.55 air idle 1.30 emulsion tube F19 air correction 1.80 ( i know these as they are same as i started with on my car )
to get you started the important bits as i understand
webers run two circuits a low speed 500-3000 rpm ( roughly ) & high speed above 3000rpm . low speed is as below and high speed by the emulsion tubes
LINKAGE SPEED SCREW 1/4 TO 1/2 TURN AFTER CONTACT WITH LEVER MAXIMUM
MIXTURE SCREW 1 TURN OUT FROM LIGHT SEAT
you also need to lightly seat the air bleed screws , when the above is done you can start the engine , it will run slow etc , dont wory about idle speed untill you set the LEAN BEST IDLE . turn in the mixture screw ( one only ) untill it runs worse then back out 1 /4 turn at a time untill you get the best idle point .do all mixture screws the same way ( you may need to adjust the idle screws , should be very responsive )
read up on the net on low speed tuning for webers they will also have pictutes showing the parts mentioned .
IMPORTANT if you have to screw the mixture screws out more than 1.5 turns the idle jet is to small .if only 1/2 turn then its to big . if you compensate by screwing in the idle screws more than the stated 1/2 turn from contact then the system is to lean and your useing the throttle discs .
MOST IMPORTANT YOU MUST DO A BIT OF READING TO UNDERSTAND WHAT YOUR TRYING TO ACHEIVE AND ULTIMATLY YOU HAVE TO HAVE THEM FINE TUNED ON A DYNO
UNLESS YOUR REALLY LUCKY
hope this will get you started and drivable cheers
 

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