Just fitted twin monoblocs to my 66 Hornet.I have fitted the carbs with the float bowls pointing out, however I have just seen several pictures of 66 Hornets and they had the float bowls facing each other pointing in over, which is correct.Thanks Gordon.
In Roy Bacon,s book of the BSA Twins on page 87 it shows a picture of a 1966 Hornet taken from the timing sde and the carb has the float bowl on the inside, But in another book by Roy Bacon covering the unit twins only on page11 it shows a picture of a Spitfire Hornet taken from the drive side and the carb bowl is on the outside and on page23 it shows a 1966 Spitfire Hornet taken from the timing side and the bowl is on the inside. If you have fitted twin carbs with the bowls on the outside then they are 2 left and right handed carbs whereas the photos in Roy Bacon,s book shows 2 same hand carbs thus having one bowl on the oputside and one on the inside.
According to the parts book the left hand carb is a 689/228, which is adjusting screws on the left so on the outside, the right hand carb is a 389/228 whicxh is adjusting screws on the right, so on the outside.
Put them with float chambers on outside you cannot tune it.
Below from the 1966 catalogue.
Just checking on the Amal catologue they say for 1966 389/229 and 689/229 for 1966/67 they say 389/228 and 689/228. looking along at the specs for both sets of carbs they are identical except for the needle position the 229 carbs the needle position is given as 4 whereas the 228 carbs it is position 3.