I've had a look in the forum through 'search', and didn't see anything on the subject of distributors, advance curves, springs, tuning etc, other than personal replies to questions.
If you go to this site:
http://www.mgaroadster.co.uk/technical_information.htm
you can get some interesting tech stuff on distributors, and also about SU carbs.
(Item No. 7 may be of interest to some members - a list of all Lucas dizzes and the vehicles they were fitted to.....which years, type numbers, specs, the lot!).
The subject of the advance springs is a tricky one, as the springs are not marked. How can one know if one's dizzy has the right springs? One of my spare dizzies hasn't - they are both under tension all the time, when one (the secondary I believe) should be loose when you have the dizzy in your hand.
How could I find out which spring I need? I read a post by 'bmcecosse' in which he said the spring properties weren't too important in a Minor engine.
Would it be any use stretching the spring which should be loose a little, to make it so? Or just not bother?
Lucas distributor info
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I still think the actual springs aren't too important in a standard Minor engine (as long as they are there!) - but in a modified engine you do really want the correct advance at all points of engine performance - the 'map' ! You can just buy the '123' dizzy - which comes with a number of advance curves built in, and with varying static advance settings will surely satisfy any requirement. Or of course go Megajolt - and develop your own map using a lap top. For most 'fast road' engine mods all that is required is a total advance internally of ~ 30 degrees (so = 15 in the dizzy) which is easily achieved by trimming the advance weight stop bar slightly. Then set it up to give 'not quite' pinking and decent idling - and it should be near enough - certainly at minimal cost! The vacuum advance unit MUST be working correctly too.
I decided to study the distributor in more depth after our chat regarding that 'little wire'. With all my BMC-type cars, I've never had any need to know more, as everything is so simple. If there's no pinking, and the revs increase slightly when you lift that pin on the carb......off you go!
The Lucas database from the link in my previous post here is useful - I have been able to identify which models my spare dizzies were used on, and in which year.
When I brought one of my Minors to Poland, I took off a distributor fitted with Lumenition electronic ignition and fitted one with a contact breaker, to make fault-finding easier in the event of trouble, which I luckily didn't encounter.
I found the dizzie with the electronic ignition fitted today - I'd forgotten all about it. I'd left the power module on the inner wing, so I got the instructions off the net, fitted the electronic dizzie and wired it up.
I got a first-time start! I've never had electronic ignition before, so I'll give it a go, keeping a spare 'normal' dizzie ready in the boot, just in case!
Although I won't be going anywhere until I finish the LHD conversion and register it in Poland......Mogski!
Tip: Easy way to find firing-stroke TDC (thereabouts) on number one cylinder.....just take the centre lead from the dizzie cap and put it 1/8 inch from an earth point, but so you can see it. Then, with the ignition switched on and dizzie cap off, crank the engine until a spark fires with the rotor arm in line with where the the number one lead would be. Then pop underneath to sort out the BTDC degree setting.....turn the engine back a bit, and come back up to the mark, to make sure you're not on the wrong side of any backlash.
Next tip: When you've done the BTDC setting underneath, leave it as it is and make a thin white paint mark somewhere on the top of the pulley, with a corresponding thin mark next to it on the block, so you can see and set it from above!
I haven't done this yet, but I plan to, even I have to add a little metal pointer tag like the one underneath. I want a strobe lamp for Christmas, you see.
Anyway, the moral of this tale is that if you strip down your dizzie and find a loose spring on the bob weights - that's how it should be! The other works right from the start of the advance, the loose one coming into operation later as the advance progresses, once the slack has been taken up.
The Lucas database from the link in my previous post here is useful - I have been able to identify which models my spare dizzies were used on, and in which year.
When I brought one of my Minors to Poland, I took off a distributor fitted with Lumenition electronic ignition and fitted one with a contact breaker, to make fault-finding easier in the event of trouble, which I luckily didn't encounter.
I found the dizzie with the electronic ignition fitted today - I'd forgotten all about it. I'd left the power module on the inner wing, so I got the instructions off the net, fitted the electronic dizzie and wired it up.
I got a first-time start! I've never had electronic ignition before, so I'll give it a go, keeping a spare 'normal' dizzie ready in the boot, just in case!
Although I won't be going anywhere until I finish the LHD conversion and register it in Poland......Mogski!
Tip: Easy way to find firing-stroke TDC (thereabouts) on number one cylinder.....just take the centre lead from the dizzie cap and put it 1/8 inch from an earth point, but so you can see it. Then, with the ignition switched on and dizzie cap off, crank the engine until a spark fires with the rotor arm in line with where the the number one lead would be. Then pop underneath to sort out the BTDC degree setting.....turn the engine back a bit, and come back up to the mark, to make sure you're not on the wrong side of any backlash.
Next tip: When you've done the BTDC setting underneath, leave it as it is and make a thin white paint mark somewhere on the top of the pulley, with a corresponding thin mark next to it on the block, so you can see and set it from above!
I haven't done this yet, but I plan to, even I have to add a little metal pointer tag like the one underneath. I want a strobe lamp for Christmas, you see.
Anyway, the moral of this tale is that if you strip down your dizzie and find a loose spring on the bob weights - that's how it should be! The other works right from the start of the advance, the loose one coming into operation later as the advance progresses, once the slack has been taken up.
Manual advance....
I've just remembered something I must have seen years ago - didn't cars use to have a manual advance, using a cable from the cockpit? The driver would make the adjustments himself, as required. I can't remember any details.
How busy with the adjustment cable would the driver have been? All the time?
How busy with the adjustment cable would the driver have been? All the time?
It was really manual retard - to let them start the thing easily using the handle ! Once running it was pretty much shoved forward to give some advance. And yes - one spring (usually the heavier/thicker of the two) should be slightly loose - but only very slightly - and some dizzies just have two 'snug' springs - to stop the advance jumping forward too quickly!
So many models, so many springs! There's no guarantee as to what you've got as there's no way of knowing what someone may have changed in the past.
Like you say...probably not a critical issue on a Minor. I've had heaps of cars with this type of distributor, which were old when I got them. I never did anything to them other than a clean, new points and condensor, and never had a problem!
I just got to thinking whether I might reduce fuel consumption and give the engine a better time of it if I got the dizzie up to scratch.
Manual Retard......good name for a punk band!?
Like you say...probably not a critical issue on a Minor. I've had heaps of cars with this type of distributor, which were old when I got them. I never did anything to them other than a clean, new points and condensor, and never had a problem!
I just got to thinking whether I might reduce fuel consumption and give the engine a better time of it if I got the dizzie up to scratch.
Manual Retard......good name for a punk band!?
Thre is no doubt that having the ignition timing EXACTLY right for any particular engine load/speed condition is one of THE major improvements in recent years on modern engines. The nearest approximation we have is the Megajolt system - and the Mini lads who have fitted this and set the 'map' up properly, report great improvements in torque, improved idling and tractability with long period cams and better economy. Fiddling about with springs is never going to be dead right at every load/speed condition!
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mike.perry
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Kevin
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Surprised you mentioned them Roy as the price is the best part of £300You can just buy the '123' dizzy - which comes with a number of advance curves built in, and with varying static advance settings will surely satisfy any requirement.
Cheers
Kevin
Lovejoy 1968 Smoke Grey Traveller (gone to a new home after13 years)
Herts Branch Member
Moderator MMOC 44706
Kevin
Lovejoy 1968 Smoke Grey Traveller (gone to a new home after13 years)
Herts Branch Member
Moderator MMOC 44706
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Alec
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Hello all,
my concern about these electronic distributor systems is that I don't see how you can set them up without some sort of dynamometer testing? Unless of course you have a standard engine and copy the mechanical curve, so what then is the point of that expense.
BMCE, you mention the vacuum advance as being important, how do these electronic distributors cope with that?
Alec
my concern about these electronic distributor systems is that I don't see how you can set them up without some sort of dynamometer testing? Unless of course you have a standard engine and copy the mechanical curve, so what then is the point of that expense.
BMCE, you mention the vacuum advance as being important, how do these electronic distributors cope with that?
Alec
Hello, Alec!
As far as I understand the electronic ignition on my Minor, a 'chopper' slides onto the cam and sits under the rotor arm. This 'chopper' is just a little plastic cross, the arms of which interrupt the reception of the LED beam by the sensor. This instigates the firing of the spark.
Because the 'chopper' sits on the dizzy cam, it is affected by the bob weights. And the sensor sits on the base plate, which is affected by the vacuum advance.
So really it all works just like points, as far as my thinking goes. Just that it's electronic instead of physical. In fact the wiring up of the kit is very simple. A red lead goes to +12v, and a brown wire goes to coil negative instead of the wire from the dizzy, which is eliminated. You're done!
Mainly I'm trying out mine because I discovered the kit costs about 150 quid, and it came with the car which only cost me 220 quid! By the time I had it up to scratch and got a straight MOT, I'd spent 400 quid. Then 100 plus quid for the head conversion to lead-free. So the value of the kit is around a third of what I've put into the car!
As far as I understand the electronic ignition on my Minor, a 'chopper' slides onto the cam and sits under the rotor arm. This 'chopper' is just a little plastic cross, the arms of which interrupt the reception of the LED beam by the sensor. This instigates the firing of the spark.
Because the 'chopper' sits on the dizzy cam, it is affected by the bob weights. And the sensor sits on the base plate, which is affected by the vacuum advance.
So really it all works just like points, as far as my thinking goes. Just that it's electronic instead of physical. In fact the wiring up of the kit is very simple. A red lead goes to +12v, and a brown wire goes to coil negative instead of the wire from the dizzy, which is eliminated. You're done!
Mainly I'm trying out mine because I discovered the kit costs about 150 quid, and it came with the car which only cost me 220 quid! By the time I had it up to scratch and got a straight MOT, I'd spent 400 quid. Then 100 plus quid for the head conversion to lead-free. So the value of the kit is around a third of what I've put into the car!
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Alec
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Hello Mick,
my comments are aimed at these totally electronic distributors with electronic (programmable) advance curves.
I have read so many posts on other web sites about how marvellous they are and easy to programme. What I don't understand is how people set them up accurately. I also believe that in most cases the 123 etc replaces a worn out distributor so comparison is not really valid.
I can see track competitors wanting to get the best set up and imagine that they take the time and have the knowledge to get them set up correctly, but the majority seem to be bought by people running fairly standard road cars.
An unnecessary expense and complication in that circumstance I feel.
Alec
my comments are aimed at these totally electronic distributors with electronic (programmable) advance curves.
I have read so many posts on other web sites about how marvellous they are and easy to programme. What I don't understand is how people set them up accurately. I also believe that in most cases the 123 etc replaces a worn out distributor so comparison is not really valid.
I can see track competitors wanting to get the best set up and imagine that they take the time and have the knowledge to get them set up correctly, but the majority seem to be bought by people running fairly standard road cars.
An unnecessary expense and complication in that circumstance I feel.
Alec
Thanks for all the previous info, it fills helps remind us of what we did know, funny how things just drift away.
I obtained a Aldon igniter electronic ignition, to suit a D45.
but then of course fitted it to a D25 on my 1098, as you do, it works ok, but I am not getting much advance, going to check bob weights etc.
What are the main differance between a D25 and D45.
Thanks win
I obtained a Aldon igniter electronic ignition, to suit a D45.
but then of course fitted it to a D25 on my 1098, as you do, it works ok, but I am not getting much advance, going to check bob weights etc.
What are the main differance between a D25 and D45.
Thanks win
South Yorkshire