Cologne carb

I have a slow-running fuelling problem with my Mk2 Granada auto on carb. If I try to pull away from a junction, it coughs and either cuts out or pulls away. This problem is only evidenced in the first 1000 revs, and the car responds fine once it’s moving. The symptoms are less evident with the engine cold. With the car at a standstill and revving it, black smoke comes from the exhaust. I’ve checked and adjusted the choke, and even run the car with the choke removed.

I was advised to check the vacuum pipe between the auto box and carb base. I tightened it, the car ran fine for a while, but now it’s come back.

The fault is more serious than it sounds, since the car is an auto and I can’t slip the clutch to get past it. Geoff Travis Email

There are two main areas that come to mind in this case. First, check that the auto advance is working. If it’s not, the ignition is staying retarded when you accelerate, which can give you a big flat spot, much like the one you describe.

Take the top off the distributor, and pull the advance/retard suction pipe off the inlet manifold. Give it a suck at the inlet end, and the plate with the points mounted on it should move. If it doesn’t, check for leaks on the pipe, then strip, clean and lubricate the distributor.

If the plate does move, the next culprit to check is the rubber diaphragm that operates the accelerator jet.

If that’s the case, you’d be wise to get a carb rebuild kit, strip the whole thing and rebuild it with new gaskets.