Hi Stephen
Once everthing else is spot on ie. plugs, timing, no air leaks, filter, dash pot oil, ect. Start by balancing the carbs.
Then to ensure each jet is set the same, wind the jets fully up level with the bridge inside the carb. Then wind dowm 2 turn's on each jet, this should set them slightly on the rich side. If you have a CO meter or colour tune use to fine tune moving each jet evenly.
OR if you dont have these it is poss to use the lifting pins found on a lot of SU carbs, these are fitted under the dash pot on the main body. If not fitted then poss to lift the piston about 1/16" with a scewdriver, DO NOT lift to high.
If when you lift it the idle gets higher and stay's high then mixture too rich. Move the jet up one flat up and re-try.
If when lifted it slows the idle or sounds like it will stall, then too weak. Move the jet down by one flat on the jet and re-try.
If the idle rises slightly then drops to normal idle, then mixture is about correct. NOT SURE HOW THIS WILL SHOW UP ON A CO METER but will have a look next time i have the FHC in work.
Also during the above the idle may alter so correct this as nec at each step and keep carbs balanced
Cheers John
LIVE LIFE A QUARTER OF A MILE AT A TIME!
1976 Speke FHC Beauty
1979 3.5 FHC(STATUS PENDING!!)
1982 2.0 DHC NOW A 4.6,ON THE ROAD NOW KICKING AR5E !!!!