Hello all and advice to a newbie

I would recommend putting the car on a rolling road as this is the best way of getting the ignition and fuel system (carb jetting) working to the best efficiency. A good operator will be able to pin point all sorts of ignition, fueling faults and even piston and valve wear if they do a leak down test. If the car is in reasonable tune then an hour should sort it out (less than £100), much more time than that and your car has some serious issues. While many consider it a rather expensive exercise you probably only need to do it once and then will be certain that all is as it should be, your car will very likely be running much smoother with a bit more performance and you'll have a good base line to refer to in the future . Alternatively they may have discovered a list of faults in the fuel, engine and ignition system that you need to fix, either way its a positive result.
If you are thinking of a rolling road session make sure the garage has lots of experiences with carbs, as this sort of knowledge is specialist stuff these days

A rolling road session would be a good investment.

The mentioning of fuel lines reminded me that it is important to get them replaced if they are the original braided type.

You need to check the grading of fuel lines carefully. Modern unleaded fuels and their additives can attack certain grades of fuel line and especially older fuel line rubber.
The standard for fuel hose is SAE J30 followed by a R number. You can check this out on the web.
You will need the number to be at least R6 but probably R9 to be safe.

Cheers

Andy

Your distributer sounds like it's not an X1/9 one, exxys never had vacuum advance to my knowledge. However one loose spring and one contacting spring is normal as that gives the right characteristics for mechanical advance. It's possible that someone has fitted a distibuter from another Fiat model and put the X1/9 advance springs onto it (I did that when fitting a Uno electronic distributer), it's hard to tell - I would leave as it is for now and look for other problems.

The flat spot you mention is something I have experienced and I was able to cure it by cleaning the carburettor out completely with cellulose thinners; soaking it overnight. Carb cleaner was not strong enough to dissolve the deposits in the carb drillings. You'll probably find you'll need to play with the idle mixture settings too but as long as you start from a known position and work methodically you should be able to find the optimum settings (wind the screw all the way in, counting the turns, until it stops - then wind it out again and try different settings) . One other major thing is to use super unleaded fuel; no ethanol and no varnish when the fuel evaporates; plus lower volatility - much better suited to a carburettor.

I'm not a fan of K+N filters; you can achieve much the same effect (better sound) by cutting off the original airbox restrictive venturi inlet. The main disadvantage of a K+N on top of the engine is that you'll suck in hotter air and loose engine power - it's no accident that the standard inlet is positioned lower and pointing towards one of the side air intakes.

Ok, so far, carb strip and rebuild, had to use original float as new one in kit just didn't measure right to setup height, top gasket split, renewed pump jet, replaced both aux venturi's as slop in both, increased main jet sizes, auto choke stripped which was blocked with glunged up. Baseplate split, ordered 2nd hand replacemment which then turned up split to. So used nimbus heat shield to make new baseplate.

Dizzy stripped, weights cleaned and lubricated, springs tidied up on posts, points cleaned and reset, reset ignition timing to #4 cylinder

Dynamic timing set to 7deg BTDC, CO set to about 2.5, K&N fitted which need some tailoring to fit correctly. K&N style cone filter to PCV breather.

New fuel hoses fitted, new run of carb fan ducting to carb base

Engine now runs really sweet, no flat spots on accel, no misfire on upper rpm band, startup up on auto choke now smoother. Engine performance clean with no hiccups. Must have spent £160 on bits and about 20 hours spanner time