Today's Message Index:
----------------------
1. 08:45 AM - FW: Coil problems (Richard Goode)
Message 1
| INDEX | Back to Main INDEX |
| NEXT | Skip to NEXT Message |
| LIST | Reply to LIST Regarding this Message |
| SENDER | Reply to SENDER Regarding this Message |
|
| Subject: | FW: Coil problems |
As I have written before, we are now making coils with an external capacitor which
we feel is a much better solution, since the capacitor seems to be the cause
of coil problems and this is directly connected with heat, so the situation
is made worse since the normal capacitor is inside a hot coil of wire!
But there has been correspondence with people suggesting testing coils by measuring
the resistance. I asked our specialist company who make magnetos and coils
for a wide variety of old and more modern racing cars whether it made any sense
to test the resistance of the coil and if one could learn anything from this.
I am attaching their reply for people's interest it is fairly clear that
you really can't learn anything significant from merely testing resistance!
Richard Goode Aerobatics
Rhodds Farm
Lyonshall
Hereford
HR5 3LW
Tel: +44 (0) 1544 340120
Fax: +44 (0) 1544 340129
www.russianaeros.com
Richard,
The resistance check doesn't really tell you much, it you got no reading for the
secondary winding or one that is inaccurate you would know the coil is bad as
there is a break in the wire, however you can get perfect resistance readings
and still have a dud coil as the insulation in the coil has failed not the wire
itself. The primary winding is not likely to exhibit any faults but also cannot
really be tested with just a meter. The capacitors are what we believe to
be a major contributor to the failures which is unrelated to the windings.
The resistance figures stated are all within what we would expect so that does
not indicated any measurable faults. The best way of testing the coils is in the
magneto itself unless you have the correct equipment for testing coils independently,
which for somebody that only has 2 mags would not be worthwhile. Baking
at 100c is too hot for the original coils i would test them at around 60c
usually, 80c max, the shellac resin used in to originals would not cope well
with 100c, nothing is achieved by this unless you have the equipment to test the
coils once baked however.
The insulated connector for the HT output referenced as a cigarette, does not need
to be tight in the slot leading to the coil, but all contacts in relation
to the HT output need to be kept clean, not to ensure the engine runs well but
to stop spark erosion, a good coil will still run fine with dirty contacts but
over time they will burn away more. I believe there is a spring in the distributor
cap that presses on the "cigarette" to ensure it connects well.
Regards,
Stuart
Other Matronics Email List Services
These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.
-- Please support this service by making your Contribution today! --
|