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Lean running SU carbs

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A

aroostok

Jedi Hopeful
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Okay, recently had carbs rebuilt, put in electronic ignition (Crane) and generally got everything cleaned up and running, reasonably so. I do have, however, some back-firing going on when accerating which seems most likely related to running too lean. I am using HS4 carbs from approximately 1969 with sprung needles. I have set the richness mixture at about 3 turns from flush with the bridge and I still seem to be running lean. I can't go much farther in richening by use of the mixture adjusting nut. Could it be I need a change in in needle from the standard AAE and, if so, what and where could I get it?
Carbs are balanced well. Was wondering if maybe a problem with advance as well.
 
G'evening, just guessing here but have you checked for leaks in the exhaust or intake manifolds?. where is your timing set? Sounds like you may be running a little hot on the timing as well. Some body here (excuse for not remem who) says "90% of all carb trouble is electrical"

mark
 
Make sure dashpots are properly oiled and working, and no air leaks around manifold or throttle shafts. You might also verify ignition timing.
Tom
 
Man! I wish I could get my ZS carb to sun lean. Lucky!

morris
 
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