Dellorto Carbburetors., Am I missing something? Options

[Petepat]

So I'm just overhauling my carbs on my 1.7 engine and looking closer with them out I notice there are 2 small pipes, not apparently doing anything by letting air into the manifold!! Question should these have caps on them? I get a lot of pop and bangs from the exhaust.

[Superhawk996]

Yes they (vacuum ports) need to be plugged.

Look carefully - should be threaded internally for brass machine screws.

Edit Note: can’t remember which is threaded - Weber or Dellorto. Just looked at DRLA parts diagram and don’t see a blocking screw so you may have to cap them. Threaded screw is much better - doesn’t crack & age and can’t be accidentally blown off by a backfire. YMMV.

Trying to refresh my memory - been a few years since I’ve worked on DRLA.

Looking at part these may work like brake bleeder - see if you can screw it in and it may cut off the passage (replace the o-ring with rebuild kit new part).

You can test this by screwing them in all the way and then blow air or carb cleaner through the port - nothing should come out inside the carb body.