Lancia Motor Club

afternoon all, just bought a LHD HF Turbo so new to Lancias in general (had a few Fiats, couple of Alfas). There's a carlos fandango dump valve thing in the turbo lines, one elbow was off completely. I've reattached it and gone from a tiny reading on the boost gauge to nothing at all. With it off it does make a boost noise, just nothing happens performance wise, the gauge does come off zero but only just.

Any advice on where to start would be greatly appreciated please

Wow..  55 views, nothing

OK. The dump valve is just that, it dumps boost back into the intake/air filter housing when the throttle is suddenly closed, like when changing gear hence the whoosh or chirrup sound depending on what type of valve it it. Neither will prevent boost being made.
If you are getting no boost have you checked to see if the turbo is siezed? Take off the large pipe at the turbo and there is room to put finger and thumb in to try and spin the impellor shaft manually, obviously without the engine running!
Assuming the turbine shaft spins freely then methodically check the pipes to see if any are split, do you get a loud whooshing sound at all?
The large intake pipes go from;
air filter housing down to turbo intake at centre,
turbo output at the angle across to the intercooler,
intercooler up to the throttle body.
If any of the ones from the turbo to the throttle body are split or not on you will get no boost, likewise if the intercooler itself is split or holed.
The small bore vaccuum sized pipes attach in various places between the intake housing at the turbo up to the wastegate actuator. Check pics of other cars, integrale is identical on set-up I'm sure so see on that, or check Rob's thread for his own HF build.
The dump valve, or if original installation it's a recirculation valve attaches to an elbow off the large pipe that is between the throttle body and intercooler. This will open if the boost raises rapidly and highly as described early as in when changing gear, so as long a the end that yours is attached to is the end that goes to the intake pipe that's ok, the other side just dumps the unwanted boost back into the air filter housing as an attempt at a crude early anti-lag.
Hope some of that helps.

Very helpful thanks, off to check hoses and poke about (with the engine off)