"brit iv just heard that 1 1/2 to 2 turns out is a good place to start for the idle mixture screws. I can't get it to tick over so i can't check how rich or week the mixture is anyway mate. It should run fine at this setting, certainly enough to tickover ok!
Iv tried it at 1 turn out 2 turns 3 turns 4 turns and 5 turns. all make no difference to making it tick over any better"
this is starting to sound a little familiar Colin!
the last time i had this, i was going round in circles with settings too, but on weber idf's,
i'm not positive that the dellorto's are the same, but if they have an "air by-pass" screw, make sure these are wound in and sealing before making your mixtures adjustments, otherwise you're wasting your time.
1.5 turns out is pretty much a standard starting point for most carb settings, but if you are finding that that you cannot adjust it enough to make a differecne, you might have found that you cannot adjust the mixture within the installed idle jet range,
they may be too small, even if stock, they may be too small.
i had this with my 1.7 8v idf's, idle jets were 50's, stock, but to get the mixtures somewhere near, they had to be about 4 turns out, ridiculous, its just masking a problem, so stuck 55's in, now 2 truns out is much much better.
carbs are a dark art mate, you're dead right, but the more you read and do, the simpler they become,
stick with it, before you know it you'll be an expert!