Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Idling puzzle

Dave, looking at the age of your car I would also look at the quality of spark you're getting and especially the condenser

When this happened to me in my 64 4/4 with the 1600 crossflow and weber down draft it was the float not being correctly set after the rebuild. Another check is to slightly increase the idle revs and see if this resolves the issue, if this is the case then it could be the timing being slightly off allowing it to run rich.

Have you carried out a plug check after one of the stalling episodes?

My suspicion is that this is a carburettor problem rather than an ignition problem. Having said that, I once had an curious problem on a Crossflow engine which would not idle below 1200 rpm - it turned out to be the bob weights in the Motorcraft distributor having seized.

Have you checked the accelerator pump diaphragm? If its perished it should drip a little petrol when you operate the the throttle lever and if it let's petrol out it will probably let air in. A new one is included in a genuine Weber service kit.

Arwyn

My mechanic and myself have completely stripped down the carb ,checked and cleaned. Also checked the accelerator pump. Put the carb back in place and the problem still persists. I tried the car on a 10 mile trip and had to increase idling speed to 1500rpm to avoid stalling in traffic although cruising on gear is normal. But idling even at 1200 rpm is not smooth. I will replace the air filter next but I do not believe this could be the cause. Sometimes the engine just dies when idling but there is no problem to start again.

MOR404, rather than throwing out a series of suggestions I would be interested to know some details... Is this Morgan new to you, if not has the fault just started recently. I note you mention carbs, plural..? Type of carbs. Is the engine tuned. Do you have the correct settings for valve clearances and ignition timing to suit the cam installed. Have you performed a compression test, are the ignition leads in good condition.. Run the engine in the dark, look for sparks leaking around the leads, dizzy cap and coil. You may have noted I mentioned using a length of rubber tube to check for air leaks around the inlet manifold to head joints and carb to inlet manifold I take it all the spark plugs have the same colour and gaps and are correct grade for the state of tune and that the spark is strong. Dependant on your location how is your fuel quality... water in the tank..? Also is the breather hole in the fuel cap clear, does the tank suck air when you take the cap off after a run...As has been pointed out already you have changed the simple stuff like rotor arm points and condenser, if fitted..and checked the advance and retard mechanism is not sticking, can be checked by holding the rotor arm and trying to turn it, it should turn fractionally in one direction and spring back. While you are in there lift off the rotor arm and add a few drops of oil on to the cotton wool if still in there, if not drop some oil on to the head of the screw that will now be visible. Clean the tip of the rotor arm by rubbing it on the tyre sidewall, ideally you do not want to take any metal off at this point as you will increase the air gap between it and the segments in the dizzy cap. The segments foul up in time give them a scrape with the blade of a screwdriver you may find crud flakes off them. Check the carbon brush that makes contact with the rotor arm check it springs or that the spring on the arm (dependant on type), makes good contact, clean the point of contact on the rotor arm.While at the dizzy pull the end off the vacuum pipe near the base of the carb or somewhere on the inlet manifold (if fitted) and suck on it while looking at the dizzy internals and the plate which the points are mounted should move and spring back when you stop sucking, proving that the vacuum advance if fitted does in fact operate...

That should keep you busy for a while.. (-: Good luck, let us know how you get on...

Having gone through the list as recommended we ended up taking out the carb again. On inspection we noted that the butterfly shaft moves when pushed sideways so we took it off to check about wear. We put on another plastic washer on the drivers side of the carb shaft and engine is now idling well at 900rpm and not hunting or dying on idle. Looks like the shat was leaking air.
Luddite I ve owned my Morgan for two years and it is a 1980 model with 36000 miles with a Webber twin choke carb.

Well done

MOR404. Good news indeed, many thanks for coming back with the resolution to your issue.

Had you used a bit of tube as suggested, I suspect you might have heard air being sucked in around the spindle...?

The reason I asked how long you owned your Morgan was to know whether this issue had been around for a while or just something that appeared recently. Knowing the answer to such questions can help fault finding.

Over the years Morgans have been modified thus chances may be that an old Morgan may have been modified with different cam, carbs, H.C. pistons, exhaust system...any or all of which details may have been lost in the sands of time, Then a new owner sets the ign timing, tappets etc as if the car was standard, expecting it to run well..

All of which matters not a jot now that you got it running well... (-:

Good news.

I vaguely remember being told that Weber carbs fitted to Ford engines had a typical life expectancy around 40,000 miles - your 36,000 is close enough.

As well as the hose, you could check the auto advance/retard is working at the distributor itself. A long time since I tried but I believe you can suck on the hose and check for movement at distributor.