dizzy wire
Dave Ireland
of some kind? what would the effects be if it were disconnected?
Speedy Jim
>
> What is the wire inside the dizzy for on the top plate.? Is it a ground
> of some kind? what would the effects be if it were disconnected?
Yes, it provides ground for the advance plate and one side
of the contact points. If it gets broken, the engine will
probably have intermittent "stumbling" or even die at certain times.
If it's broken, you can at least temporarily solder the end back on.
The pigtail flexes quite a bit as the advance plate moves,
so a solder fix won't last forever.
Speedy Jim
http://www.nls.net/mp/volks/
Dave Ireland
Speedy Jim
>
> What is a more permanent fix then?
You'd have to find another braided pigtail and put
suitable terminaions on it which can be riveted/screwed/soldered
to the plate and the case. The braid has to be pretty fine
so that it doesn't impede the movement of the advance.
Speedy Jim
http://www.nls.net/mp/volks/
Veeduber
Make a new pig-tail.
Start with a generator brush. (Old one is okay). Fracture the carbon brush &
remove. Cut away about 90% of the wire. Use the other carbon brush as a spot
welder. File/grind it to a point about 1/8" in diameter. Use your car battery
as your power source. The leads need to be at least 10 gauge (more is better).
POLISH the placet where you wish to weld the pig-tail. Hold the pig-tail in
place where you want it to weld-to using whatever clamping arrangement you can
get to work and the sharpened carbon brush as part of the clamp. (Remember to
keep the clamp electrically isolated so as not to short-out the electrode.)
Have your lead already attached to the sharpened carbon. (Use small nuts &
bolts; spring clips are no good for this application.) When everything is in
position, complete the circuit by holding the lead against the negative pole of
your battery.
If you've got it clamped properly, when you close the circuit the thing will
smoke a bit and start to glow. Takes about one and a half seconds with a hot
battery.
That's it.
...except for a few thousand things that can go wrong :-)
So why can't you just solder it?
Go ahead and try. You'll discover that by the time you have the PLATE hot
enough for the solder to flow, it will have wicked into the fine-stranged
pig-tail turning it into a solid bar and thus defeating the function of the
advance plate.
Which is why they spot welded it to begin with.
Basically, you're spot-welding copper to steel, a rather special application of
the spot-welding process. You need to use procedures that, while similar to
spot-welding steel-to-steel are not exactly the same, such as the fact you
can't use a copper electrode (the pig-tail will simply weld to the electrode).
An old set of points can be made to serve as the top electrode (tungsten
doesn't weld readily to copper) but a carbon electrode is best and really isn't
all that difficult to make. The tricky bit is providing a high-amperage
connection between the carbon and the power lead,. By using an old generator
brush as your electrode that's already taken care of.
----------------------------
So why a generator brush?
Two reasons. The lead must be extra-flexible or it will effect the
distributor's advance-response. Distributor brushes have that type of lead,
only on a larger scale. So you simply cut it down.
Robert Bosch & Co won't sell the lead -- although they will sell you the
complete advance plate.
------------------------------
On the other hand... if you're running a CDI module the points are only to
provide the signal -- a few milliamperes -- instead of switching the current to
the coil -- up to ten amps inrush. If you're running a CDI module that means
you can use a little pig-tail of Litz wire, wound into a little coil and
secured with regular CRIMPED terminals. (Litz wire is ultra-fine,
multi-stranded wire used in meter movements. You can buy a tiny spool of it...
for about ten bucks :-)
-Bob Hoover
Alan Nelson
here.
Mr. Hoover: Once again you have provided a neat little tidbit of knowledge
to us mere mortals.
I thank you.
--
Alan Nelson
www.boatcop.com
___
/___\ Proud Owner of a
(0\_|_/0) 1969 VW Bug
U U "Tizzy"
"Veeduber" <veed...@aol.com> wrote in message
news:20020608233730...@mb-fy.aol.com...
Jim Adney
>...except for a few thousand things that can go wrong :-)
I make replacements from "solder wick" which is sold in a number of
gauges so you can pick one that looks just like the original ground
braid. You have to take the breaker plate out of the distributor and
disassemble it, but then you can tin the connection points on each end
and solder the solder wick to those points. Make sure to make the
replacement just as long as the original to preserve it's flexibility.
Done this way, my replacements seem to last as long as the originals.
That is, they seem to last forever unless they are abused.
This method isn't nearly as interesting or exciting as the spot weld
approach, but it IS something that almost anyone who can solder can
do.
>------------------------------
>
>On the other hand... if you're running a CDI module the points are only to
>provide the signal -- a few milliamperes -- instead of switching the current to
>the coil -- up to ten amps inrush. If you're running a CDI module that means
>you can use a little pig-tail of Litz wire, wound into a little coil and
>secured with regular CRIMPED terminals. (Litz wire is ultra-fine,
>multi-stranded wire used in meter movements. You can buy a tiny spool of it...
>for about ten bucks :-)
While there is no obvious reason for it, the CDI units I'm familiar
with actually stack up a parallel array of resistors to increase the
current thru the points. They claim that this is necessary for the
points to stay clean. This resistive current doesn't lead to point
erosion like the inductive current normally drawn by a coil in a
normal Kettering ignition.
Litz wire is used lots of places, but I've never seen any in meter
movements. All the meters I've ever worked on were wound with single
strand magnet wire.
Where can you buy small quantities of Litz wire? The only place that
I'm familiar with that makes it in the US is New England Wire and
Cable, and it is usually custom made. We've got a couple of hundred
pound spools of some from them that is nearly 1/4" in overall
diameter, but that's nothing compared to the stuff I had them quote on
which was 1.8" OD. The price for that was outside our budget, so we're
pursuing an alternate solution.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, Wisconsin USA
-----------------------------------------------