Weber IDF

[Redline]

Perhaps a stupid question, but what are the hoses that come off the base of the IDFs and connect to the air filter? The brass fitting is on the bottom right in this picture:



What do you do with these lines if you switch from the UFO to lunchbox or foam filters?

[mscafide]

That is a fuel return line back to the fuel tank.

Mike

[BEEK]

if you are refering to the vacuum lines that come from the base of the carb, you can plug them off

[sptcoupe]

Actually, it is the vacuum connection pipe to the air filter box. The fuel return is on the other side of the carb.

[Redline]

Thanks for the quick answer! So what was the point of running two vacuum lines up to the air cleaner?

[sptcoupe]

On the older model IDFs, these ports were/are used to provide the vacuum for older style distributors, particularly on older VWs with the very common SVDA ignition distributors. The newer Webers have a small brass tube with a screw in it, one for each bore.

I have seen some cars where they were being used to provide the vacuum for the brake booster. They won't work for that at all.

I don't know what type of ignition/distributor you plan on running, but if it doesn't need a vacuum advance source, just plug it up.

[mscafide]

Ah, true. It's been a while and I do recall running a hose from one carb to the other to block it.

I just got the car back an hour ago and now that it is pretty again (just paint and some detail work) and it really needs me to install an interior that I have had laying around for a few years and give it a good top. Thank God it's winter.

Mike

[sptcoupe]

I don't think I have ever had a FIAT project that ended until I sold the car - and I have one now that I have owned for 26 years and another for 13 years!

[JerryH]

I have dual IDF 40s and lunch box filters that the PO installed. He routed the output of the crank breather through a hose diameter reducer and into one of these vacuum connections. Any opinions on this?

[sptcoupe]

The output from the crankcase should be routed into the filter box and inhaled through the carb, not dumped directly into the air/fuel mixture below the throttle plate. Plug up the vacuum connector pipe and route the PCV output into the air filter box. You'll be happy with the results.