Paul L I'v had great successes tuning carbs using a pair of COLOUR TUNE kits and a balance gauge.
With one COLOUR TUNE tube in cylinder No1 and one in cylinder No 4, I find I am able to match the ignition colour at low rev's.
I then balance the carbs with the vacuum gauge.
Then repeat both the steps again.
So fare this method sorted out any fuelling problem I'v had.
It's helped to identified different size needle jets in a pair of SU's, which until then were giving me loads of grief .
