DCOE conundrum
Discussion
I have a pair of 40 DCOE Webers fitted with 28mm chokes (fitted to a 1.3 Alfa Giulia).
My problem is that at idle, when attempting to balance/sync the bodies, barrels 1 & 2 on carb 1 are the same, but barrels 3 & 4 on carb 2 are not the same. The difference is about 1-1.5 kg/hr of air.
Easy I thought, the spindle is bent. Prior to removing the carbs, I did a crude check by removing the progression holes cover and checking to see where the butterfly was for each barrel on the problem carb at small throttle openings by shining a torch down the venture. In a pitch black garage, I couldn't discern any difference between the barrels this way.
I then removed the carbs and did a light test against the butterflies in the venture to check for rings of visible light. Both barrels appear to be the same.
A quick google suggested I look at the air bleed screws, but upon closer examination, my (Italian) bodies don't have air bleed screws fitted.
Any suggestions? The differences were found using an air flow meter.
My problem is that at idle, when attempting to balance/sync the bodies, barrels 1 & 2 on carb 1 are the same, but barrels 3 & 4 on carb 2 are not the same. The difference is about 1-1.5 kg/hr of air.
Easy I thought, the spindle is bent. Prior to removing the carbs, I did a crude check by removing the progression holes cover and checking to see where the butterfly was for each barrel on the problem carb at small throttle openings by shining a torch down the venture. In a pitch black garage, I couldn't discern any difference between the barrels this way.
I then removed the carbs and did a light test against the butterflies in the venture to check for rings of visible light. Both barrels appear to be the same.
A quick google suggested I look at the air bleed screws, but upon closer examination, my (Italian) bodies don't have air bleed screws fitted.
Any suggestions? The differences were found using an air flow meter.
stevieturbo said:
If one carb is different than the other, the obvious place to look is the throttle linkages between the two.
Unless you're removing carbs/manifold/linkages all intact you may not see the problem
Hi. The problem is between barrels on a single carb body, not balancing between two bodies.Unless you're removing carbs/manifold/linkages all intact you may not see the problem
stevieturbo said:
So....Can you swap carbs side to side, to see if problem stays on came cylinder ?
Maybe for some reason there's an odd variation in the amount of air that cylinder is pulling vs the rest ?
That was my next train of thought!Maybe for some reason there's an odd variation in the amount of air that cylinder is pulling vs the rest ?
Also, similarly to how carbs are often setup on a bike, I was planning to experiment with using a piece of pipe attached to the vacuum take off points between the two barrels to equalise the pressures on the engine side of the butterflies. This would still show different readings on a flow meter attached upstream of the throttle plates though...
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