The car just won't run right.

[Lukey]

When I first got the car it didn't run correctly, it missed a bit on idle and on cold mornings it would sound as if it was only running on 3 cylinders for a min or two and hesitate when driven. Although when warm the car ran fine, it would do 85 mph with three people in it, 0-60 16.10 seconds with two people in it.

I finally had a day off work and could service what I hadn't done to it yet, so I adjusted the valves, put new plugs in, new points, new condenser, new dizzy cap, and new rotor arm. I drove the car for bit ran pretty much the same as before, got the car home laid it up. Drove the car again a few hours later, same route but this time it pinked halfway through.

I have never set the timing before on a car so I followed the manual and set it to 5 deg before tdc which required advancing, for the first time the car idled beautifully from cold but pinked and had a rough idle when it warmed up. So then I just retarded the ignition until it stopped pinking now the pinking has stopped but the idle is rough again.

I borrowed a timing light, I disconnected the vac line and set the idle as low as I could. I then saw that the ignition was way off the timing marks but it was also oscillating. It just doesn't stay in one place and when ever it oscillates it advances. Is this my problem? Did it just randomly coincide with me servicing the ignition and setting the valves for the first time?

[eastona]

Have you checked

vacuum advance unit working correctly?
Is the points gap correct?
induction air leak?
Is the timing moving with the car idling and not revving etc? i.e. of its own accord? is the dizzy really badly worn?

Is the choke working correctly when it's cold?

85 with 3 up's a bit ambitious

(probably amibitious with 1 up!!)

Andrew

[bmcecosse]

85 mph and 16 seconds to 60 doesn't sound like a standard Minor to me !

YYour symptoms suggest the vacuum and/or the mechanical advance in your car are not working. Take dizzy cap off - twist the rotor arm with your fingers - does it move and then spring back ? If not - investiagte further by taking the dizzy out and to pieces! To test the vacuum advance - take the little tube off at the manifold and suck (be ready to spit!) on the tube while watching the dizzy baseplate. The suck should produce a vacuum (if not - diaphragm is bust) and that vacuum should make the baseplate twist noticeably and then relax when you stop sucking! If not - it's needs replacing. The best 'running' timing for an engine is when it's 'just not quite pinking' - and unless the advance mechs are working properly it may run well enough (as you describe) but may not have a good idle. If there are multiple problems with the dizzy - may be worth trying a complete different one.

[Lukey]

Have you checked

vacuum advance unit working correctly?
Is the points gap correct?
induction air leak?
Is the timing moving with the car idling and not revving etc? i.e. of its own accord? is the dizzy really badly worn?

Is the choke working correctly when it's cold?

85 with 3 up's a bit ambitious

(probably amibitious with 1 up!!)

Andrew

Vac working, points set to 14 thou, no induction leak, timing was moving at idle.

To remove the dizzy do I just loosen the pinch bolt and pull it? To put it back I just put it back in and set the timing again?

[Lukey]

I'll get the gps out to see if my speedo has had it, What does everyone's usually top out at?

[eastona]

yes, just loosen the bolt and work the dizzy back and forth and pull it out. If you put it back at the same place the timing will be fine.

(that was a bit obvious really, I wasn't trying to be clever you could mark it, to put it back the same)

is the choke working ok?

you should be able to tell if the distributor's worn without taking it out.

agree with BMC. I'd be mega chuffed with 16.1 seconds and 85 is not something I visit regularly (if at all!)

Andrew

[Lukey]

Heh, I'll have a look at the dizzy now for wear. Yeah the choke is fine.

[PSL184]

I don't think a standard Moggie is capable of anything like 85 and especially not a sub 20 secs to 60 Speedo may well need replacing but that won't help with your idle stumble. It sounds like the breathing is not correct so check again for air leaks around inlet manifold and also check the breather hoses from the engine breather. Also, have you the correct oil cap fitted ???

[eastona]

good point about the breathers, it would make it really weak at idle. It's worth checking.

Wouldn't explain the erratic idle timing though which would be of concern. It does wander a smidgen, but not much.

mine cruises nicely at 60, goes OK at 70, haven't dared take it past 80 downhill on the way to the start of LEO in case I ended up catching pistons as they leapt out the engine.

Andrew

[Lukey]

Breather fine, oil cap standard and has a good seal.

[MarkyB]

So is it a standard engine?
If it is then its been breathed on a bit (or you timings are way out)
Points should be 12 thou, plugs 25 and tappets 12, maybe 15 if you are going to cane it.
Timing jumping about is a symptom of a worn distributor is afraid.
Don't let it pink because the engine will definately get damaged
If you have, or can get hold of a compression tester it would be worth checking the compression.

[PSL184]

But... is it a vented cap or a solid cap? Where does your breather pipe from the engine go to??

[Lukey]

It's the solid black plastic one and the breather exits the rocker cover at the front of the engine and goes to the airbox. Compression test done all showing mid 150's, exept cylinder 1 which was showing 149. I'll do the dizzy tomorrow as I no longer have a lower back.

[Dean]

Lukey, when you find the problem can you post it please. These things are always good for everyone else to read and learn for when we have them.

Thanks

[bmcecosse]

Can't see what the oil cap has to do with it!!
This problem is simply about ignition timing - and proper control of it as the engine speed varies.

[alainmoran]

Might be clutching at straws here, but have you tried setting your mixture?

Missing and lumpy running at cold sounds like an over-rich mix to my inexperienced mind ... mine used to do this until I learnt how to set the mix from reading one of the FAQ's on here!

Getting better when it gets warm could be explained by the warmth of the engine being able to more completely atomise the fuel.

I've been wrong before though.

[eastona]

I think he was just checking the breathers for air leaks?

This problem is simply about ignition timing - and proper control of it as the engine speed varies.

Yes, I think that's the main culprit, it currently seems to have a life of its own!

the performance figures are well impressive though. It's either not a standard 1098 or it's got a dodgy speedo.

Andrew

[PSL184]

Can't see what the oil cap has to do with it!!

I had an idle stumble because I had the wrong (vented type) of breather on my engine. Once I changed it for the non vented type it idled OK..... The type of cap you have depends on where the engine vents to......

[bmcecosse]

Well yes - but there should be a flow of air into the engine anyway through an open breather and I hate these 'breathing' oil caps because inevitably smoke and oil fume come out at some point and mess up the rocker cover - and mess up your lungs if you are breathing the stuff!

[PSL184]

I try not to drive with my head under the bonnet