Welcome to the Austin Seven Friends web site and forum

As announced earlier, this forum with it's respective web address will go offline within the next days!
Please follow the link to our new forum

http://www.austinsevenfriends.co.uk/forum

and make sure, you readjust your link button to the new address!

Welcome Austin seven Friends
This Forum is Locked
Author
Comment
Dynos and dizzies.

Before posting this I've spent ages searching for answers to no avail.

1) What do I do with the dyno (c35a) connections if running without a battery?
2) On my dizzy,late type auto advance 'peg' drive to rotor, there is a long flat spring like thing connected to the condenser terminal which zooms back round the circumference of the bottom housing, finishing up next to the post on which the spring contact fits, but not actually fixed to anything here. Have I got a bit missing or what? I am rebuilding the car 1931 RM, and have never had it running.
Thanks in advance for any info here.
Cheers, Dave

Re: Dynos and dizzies.

Dave.

On the first question. YOU MUST NOT RUN THE ENGINE ( DYNAMO ) WITHOUT A BATTERY CONNECTED.

If you try and run the engine with dynamo without a battery there is no form of voltage regulation; the battery controls the voltage level of the whole system. The dynamo produces more volts the faster it turns, the Austin Seven dynamo produces in excess of 40 volts when the engine is reving at speed. Every electrical item has a built in safety margin when it comes to the voltage carrying capacity, often in the region of 100% ( a 6 volt appliance will just cope with 12 volt ) but to put 40 volts through a 6 volt item is a sure recipie for burn-out. This would include the dynamo ! PLEASE DON'T DO IT. I am sure Reckless Rat and others who have greater knowledge than I will give you a better technical answer.

Question two: "there is a long flat spring like thing connected to the condenser terminal which zooms back round the circumference of the bottom housing, finishing up next to the post on which the spring contact fits, but not actually fixed to anything here."

It does connect to two things, below where it connects to the condenser, it projects down through the bakelite casting and connects to the terminal on the ouside of the distributor body ( where the thinner wire goes to the coil ). The other end of this strip should connect to one side of the contact breaker. Although the connects may not be obvious, check them with a continuity tester and you should see what I mean.

On a personal note, I prefer the earlier distributor as these are less prone to wear and therefore make it easier to set up the ignition timing. A worn type of the later distributor can cause all sorts of ignition timing problems as the automatic advance and retard will flap about varing the timing in an uncontrolled way. You should also match the later distributor ( there were two types a 3 degree advance and an 8 degree advance )to your engine. If you have a low compression head on your engine then you should be using the 3 degree type, a high compression head then you should be using the 8 degree type.

Good luck with the restoration, have you joined a local club? It pays to do so BEFORE you put the car on the road as club members are often keen to help with advice.

Re: Re: Dynos and dizzies.

I think if you remove the brushes you could run without a battery? Not sure why you would want to? I suppose for speed events you could strip the dynamo right out (remove the field coils etc) to save weight and remove the power loss associated with the dynamo whilst still driving the dizzy. I presume this is not the case and you just want to run the engine up to "check it". When I first ran up the Colander I hadn't yet built the wiring loom, so I just connected everything up temporarily with some odd bits of cable and "jump leaded" to another car for power! you only realy nead some juice to the coil and connect up the dynamo to test the engine.


Steve

Re: Dynos and dizzies.

Hello Dave and Co.,

Well, if I had to run an engine without a battery, and I assume that means I would have a magneto to provide ignition, I would simply disconnect the field circuit. Without field excitation, the dynamo will not produce output (other than a very small voltage arising out of residual magnetism in the poles)

In fact, I probably would carefully remove, insulate and mark both the "D" and "F" wires from the Dynamo just to be safe.

BUT UNDER NO CIRCUMSTANCES SHOULD A "CONNECTED" DYNAMO BE ALLOWED TO OPERATE WITHOUT A BATTERY UNLESS YOU HAVE DEEP POCKETS AND ENJOY REPAIRS FOR REPAIRS SAKE!!

In respect to the distributor question, I think Malcolm has summed it all up, but I must say you threw me a bit at first with the "zooming about" bit. On first reading I thought you had some mystery item actually whirring about in the nether regions of the distributor.

If I might request a boon, I would really appreciate confirming just what is written on the little plate on the side of the distributor you are using. I have spent hours and hours with my head inside contemporary Lucas Catalogues, trying to establish just what and where the various changes were to the electrical equipment specifications of the Austin Seven.

I think the Distributor you have will be the Lucas Service No. 405508 (BN86)

Not that it really matters, I don't quite agree with what Malcolm has said about the 3 and 8 degree Distributor applications.

On the basis of the Lucas Catalogue information, I think that the 3 Degree Distributor (Lucas Service number 400289)was introduced with the Ruby in 1934 and lasted until sometime probably late in 1935, when it was replaced by Lucas Service No. 404440 BN30, which was an 8 degree Distributor. (I have certainly found 404440's with a date stamp in February 1936)

I have surmised that the 3 degree Distributor was a very conservative application of the automatic advance system and the benefits of some additional advance was taken up by late 1935 or so.

I know what the Austin Service Bulletins say about a new Distributor for the high Compression Head, but I think that refers to the S/N 405508

By the immediate post war period, by the way, Lucas were listing the 8 degree Distributor to replace all Austin Seven DK4A types 1934 - 39. That information is clear from the "B90 Scheme" Catalogues.

The Service replacement distributors were lablelled either Service No's 400206 or 40224/S. (and I think the different numbers simply reflect a change in the Lucas numbering system, rather than a change in Distributor characteristics).It is interesting to note that these later types were also specified for a range of other Austin cars of the 1930's (were supplied without clamp plate and drive gear)

All the above info is provided not with the purpose of trying to prove Malcolm wrong, but rather to perhaps to try and encourage some further information coming forward.

So, the info on those little plates on the side of the Distributor body may have information which could help unravel the above mysteries which I am prepared to concede are probably of no interest to anyone except myself.

Regards,

Barry R.

Re: Dynos and dizzies.

What a wonderfull website this is! Thanks for the replies.
Steve is correct in surmising that I simply want to run the newly rebuilt engine up with a lash up wiring system. I don't have a battery and don't really want to purchase one until I am ready for the road. I was going to use a 6v dry battery to provide sparks.
Regarding the 'spring thing', I have found a replacement which is intact, with the terminal on the end that fits on the post under the the cb spring end(the old one referred to above had the end broken off).
Cheers, Dave

Re: Dynos and dizzies.

Hi Barry,

I knew you would have better information than I had. Indeed I think I referred to you as 'Mr Lucas' in a previous forum message.

As I have said before, this is an excellent forum with just the right blend of serious and humour ! However, to repeat a comment recently made by another subscriber, could something be done to collate all the technical replies into an easy researchable section of the forum ? I realise both Jason and Mac are busy chaps but if they do have a moment.

Re: Re: Dynos and dizzies.

Hello Chaps (and Ladies),

It's now after midnight here, but I thought I should come back and further clarify an aspect of running an A7 Dynamo without a battery.

I am fairly certain that the type of dynamo on which the question was asked was the C35A, and that it is the one with externally mounted "Field Resistor" for 1/2 Charge purposes.(in a little Fuse Box on top of the dynamo) My advice was on the basis that at least the Field connection "out of the Dynamo" should be "opened", and preferably both "F" and "D" connections be opened, and the attached wires insulated and marked. In theory, just removing the "Field Fuse" would work, but I personally think that it is better to actually remove the connections right at the Dynamo

That advice still stands, but, just in case there is someone reading this thread, who wants to perform the same trick with other model Dynamos I think I should add the following.

On type 35M Dynamos, the same advice as above would apply. On this particular Dynamo the "Field Resistor" is contained within the CFR/CFR2 Cut Out Box so that is all OK ...

But....

When we go back to the Vintage Models, on 1928 and forwards Coil Ignition Chummy etc the DEL (CAV=Lucas)Dynamo was fitted. This Dynamo has the doubtful honour of having the "Field Resistor" tucked nicely up internally in the Dynamo Field Windings. Now these "Field Resistors" are frequenty found to be open circuit and are a fair beggar to replace. But in the miraculous situation where that field resitance was indeed intact, then the method I earlier advised would not work as the "Field Resistor" is permanently wired across the "F" and "D" terminals ("F" = "SH" on some Dynamos)

So....
The way to make such a Dynamo safe to operate without a battery would be to remove the Field Coil lead off the "Third Brush" obviously carefully insulating it etc. I would also remove, insulate and mark the cables to the Dynamo to be certain that the Dynamo was isolated.

The same advice would apply to Magneto engines, but here I am not familiar with specifics, and would probably opt for disconnection of field winding at the Third Brush.

On the matter of using dry cells to run the ignition for test purposes, acount would need to be taken of the fact that somewhere between one and two amps of current will be drawn out of the cells. Rechargables might be the answer if any lengthy service is required


Oh what a tangled web we (or was it Joe Lucas) weave.... etc.

Regards

Barry R.

Re: Dynos and dizzies.

Barry R,
Regarding the serial no. of my distributor, unfortunately all that is left of the brass plate are two ends under the rivets. Why would anybody remove the id plate?
Regarding the comments on dynamos and no battery, I have been sufficiently scared off making any attempt to try it!
I seem to remember that on the old 6v. motor bike systems, all that you had to do to run without battery, was to connect the two battery terminals together and make sure that the headlight was switched on. I think though that a regulator was incorporated in the charging system.
Thinking ahead, could a motorbike regulator be used on tha A7? If so would any advantage ensue?
Cheers, Dave

Re: Re: Dynos and dizzies.

Dave

Reference motorbike regulators and voltage regulation in general there have been lots and lots of posts fairly recently on this forum, one of which had an interesting link to a website, that may have been speedex or something like that, cant remember precisely, but if you trawl through the forum archives there is lots of info.

Regards

Steve.

Re: Re: Dynos and dizzies.

Dave,
I am sorry if you have been "scared off" as that was not the intention. As an Austineer you must be bold and fearless. However, if you are in that condition in respect to that matter, then let me assure you that an "adventure" with "regulators" ought to conjure up even worse nightmares.

Austin Sevens use a three brush Dynamo system, which is of itself "self regulating." In certain circumstances people can and have modified the set up using other components. I will stick my neck out and say that the use of two bobbin type electromechanical regulators, either those out of later motor cars or the MCR1/MCR2 types out of motor cycles is an unreliable, frustrating road to follow, due to burning of contacts and fundamental incompatibilty with the three brush system.

There are other roads to follow, including conversion of the dynamo to 12v, which can give excellent results and total reliability, but that is another whole subject.

Motor Cycles have never been my forte, so I can't really comment on what happens there, although I would have to surmise that you might be talking about cycles fitted with a "magdyno."

If you simply want to run your engine from time to time because you
a. want to and/or,
b. enjoy annoying the neighbours
c. like the smell of it all
c. want to gas the cat

and you have a "modern" fitted with 12v, then I would suggest that, you buy beg or steal a 12v coil and use the battery out of the modern for A7 experiments. Just don't turn on the lights.

If you have a wife or girlfriend, why not borrow the battery out of her car, as then you can be certain that YOU will not end up with a flat battery. Second thoughts though, you may then suffer from assault AND battery, but then time cures all woumds!

Best regards,

(I'm off to Junior Soccer with my Grandsons in the Chummy)

Barry R