Engine idle

[Wookie66]

Hi all
Moving on from the not running phase the car now runs and drive well apart from braking at intersections and roundabouts
The engine stalls I think it’s something to do with the power brake.

Is it a matter of just idling the engine up ?

Having to brake, clutch, change gears and use the accelerator to keep the revels up all at the same time is annoying

Thanks
Trevor

[mcl1959]

Power brake should be attached to vacuum at the same spot in the manifold where the windscreen wiper pump is attached.
If this is all correct and no leaks around this area, then I would suspect your booster is faulty or incorrect for the car.
The booster should be VH24 as per original accessory equipment or VH 44 which is suitable for drum brakes.

Ken

[ardiesse]

OK, then . . .

If the engine stalls when you come to a stop, the idle mixture isn't right.

The first thing to do (temporarily) is disconnect the brake booster.  Disconnect the booster's vacuum hose at the inlet manifold and tape up the manifold fitting.  Go for a drive.  Does the car still want to stall at lights and roundabouts?  No means you a vacuum leak anywhere between the manifold and the booster.  Yes means the idle's not set correctly.

Idle Setting
There are two adjustments: mixture and speed, with a screw for each.  The idle speed screw is the slotted-head one on the throttle lever.  The mixture screw is a knurled brass screw at the bottom of the carburettor on the side that faces the  rocker cover.

Make adjustments only when the engine's completely warmed up.  If the engine doesn't stall at idle when warm, you don't need to adjust the idle speed (yet).  If you have to pull the choke out a little to keep the engine idling, turn the idle speed screw clockwise bit by bit until the engine idles with the choke pushed all the way in.

Now for idle mixture.  With the engine idling, turn the mixture screw outwards slowly until you hear the engine begin to slow down.  Now turn the mixture screw inwards very slowly.  The engine idle should speed up, go through a "happy" region, and then slow down quickly as you lean the mixture.  When you go past the "happy" region, turn the mixture screw outwards until the engine's happy again.

It may be now that the engine's idling too fast for your liking: turn the idle speed down and reset the mixture if necessary.  This should be all you need to do.

Here are some more advanced tips -

Give the engine a bit of a rev and listen to how it recovers when the throttle's closed.  If the idle "sags" and then comes back up to normal speed, the mixture's too rich.  Lean it out a little.

Give the engine a good rev.  Does it hesitate or "bog" right when you open the throttle?  Ignition timing's too retarded and needs to be advanced a little. (Loosen distributor lock bolt, push the vacuum advance a few mm toward the pushrod cover, tighten lock bolt.)

Slowly increase the revs from idle until the motor's running at highway speed.  As the revs increase, does the motor start to "hunt" and run unevenly, almost like it has an irregular miss?  This means the ignition timing's too advanced.  You need to retard the timing: rotate distributor a little so the vacuum advance moves away from the pushrod cover.

Rob