48 IDA Balancing

[Stoo the worm Simpson]

This weekend I thought I would balance my carbs, seeing how they had been cleaned and rebuilt.
so I warmed the engine up to operating temp, and disconnected the linkage, then using snail gauge I measured the airflow to each carb....this is where I got confused...!
one side was showing about 7kg/min and the other side was about 10kg/min. this is with both the idle adjustment screws all the way out, so the carbs are in their natural closed position.
Obviously I need them to run the same, and I don't want to mind the other one out so they are both running 10kg/min, as it will be idling at about 2000rpm....!
Does anybody have any ideas why one is running a lot higher than the other, and how to sort this out...?
I'm running a rotary fuel pump, which is meant to only put out 3.5, and my idle jets are 60s.
Any help would be greatly appreciated.
Thanks in advance
Stuart.

[leec]

Are you sure the linkage tab on the carb is sitting fully returned on the throttle stop? I needed a slightly stronger return spring on one of mine to fully close the carb. May explain the differing snail readings

Lee

[Stoo the worm Simpson]

Hi lee
If I push it back by hand it does seam to go further back...
I have never run return springs though as my berg linkage has always been good enough to return it...!
I did add some once, but I got a very stiff throttle pedal.

[leec]

What about leaving one side connected on the berg linkage to carb, and balancing the disconnected carb to match the other?

[Stoo the worm Simpson]

yeah that is an option, but I don't want to end up with it idling at 1500rpm haha...but I shall give it a go

[leec]

Is that what it idles at now?
Lee

[Stoo the worm Simpson]

It does when warm with the linkage disconnected

[leec]

Were the shafts removed for rebuild?

[Stoo the worm Simpson]

yes mate

[leec]

I've never took them apart to that extent. Hopefully someone else will chime in with a solution. Good luck
Lee

[dragvw2180]

Since someone took the shafts out I would check to see if when closed do the butterflies close all the way or not . If not I might try gently adjusting the tangs .

[Stoo the worm Simpson]

Well I took the Carb off this morning to have a better look, and I have noticed a couple of things...
Firstly the top of the carb hadn't been tightened down all the way, so would an air leak cause this..?
Also the linkage tab is sitting about 5mm away from the throttle stop when fully closed, but the butterflies appear to be fully shut... and there is slight play in the linkage tab on the shaft, so possibly worn tab, or a twisted shaft.
 other than this, I'm at a bit of a loss...!

[alex d]

try to loosen the butterflies and reseat them, they might be off centered, assuming they are not upside down

[Stoo the worm Simpson]

right I have looked at the butterflies, and they are in the right way round, but maybe not centered, so I have reseated them and it seams to operate better off the car now, so I will put it back on tonight, and double check the otherwise too.

[max Der Bahnstormerz]

try losening off the butterfly screws and tgenn tighten the spindle ens nuts. then back off the throttle stop screw. Now try to seat the butterflies so amost no light is visible then shining a torch down the carb bore