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Cal-look/High Performance => Cal-look => Topic started by: volksnut on January 30, 2010, 20:39:20 pm



Title: question on air bypass screws on Dellorto carbs
Post by: volksnut on January 30, 2010, 20:39:20 pm
I noticed that when setting up a set of 45's on my 2176, the 3/4 carb wouldn't flow lower than a 7 on the snail ... the 1/2 side I could get as low as I wanted....both barrels on 3/4 were flowing the same though at 7, and the throttle plate was closed (screw not touching arm). Now.... to get both carbs to flow the same, can I open the bypass screw to lower the 3/4 carb down to meet the 1/2 carb or is that cheating? If both carbs are set at 7 then it idles at 1200 rpm :-\  Hope I explained it simple enough


Title: Re: question on air bypass screws on Dellorto carbs
Post by: Rasser on January 30, 2010, 21:46:26 pm
Before trying to "cheat" by adjusting the bypass screw, check that the throttles on both carbs are exactly the same amount opened. To verify this, check that they have the exact same distance from throttle to the first progression hole. Also hold the carbs towards a lightbulb, and see if the throttles are closed the same amount (feeler "blade" gauges) can sometimes also be used to verify this.
 IF the throttles on both carbs are perfectly aligned/synched, then it is time to check if someone before you messed with the bypass screws!

But if you are lucky, then your problem is that the throttle plates are slightly misaligned on the 3-4 carb bores, and then you can probably correct this by loosening the screws that hold the throttle plate, and then adjust them properly, so they will close better. That way you can probably turn the idlescrews further back (close the throttle plates better).



Title: Re: question on air bypass screws on Dellorto carbs
Post by: Bruce on January 31, 2010, 00:15:00 am
... can I open the bypass screw to lower the 3/4 carb down to meet the 1/2 carb ....
Won't work.  Opening the bypass screw increases the air through the carb.