08-08-2020, 10:07 PM
Sadly I suspect the windings Alan.
Try warming the mag in the oven to working temperature and test again. I think you may find a very weak spark.
There is a vent in the BTH that requires a gentle flow of air to cool it. This is often blocked with shellac from previously failed windings.
A lot of mag restorers do not clear this - it is a pesky thing to do.
My recent experience with mags is that to get reliability you need a hotter plug D21 - with D16 they start to miss on the overrun - the mag windings then heat up and it then may fail.
I know there is a safety spark earth in the mag that supposedly protects it - these are not very efficient and are rarely correctly adjusted
Since I have adopted this approach i.e. the D21 plugs mags for me are very very reliable.
I am convinced this is a change needed for modern fuel. I am afraid I don't understand why.
Hope this is of some help to you.
Try warming the mag in the oven to working temperature and test again. I think you may find a very weak spark.
There is a vent in the BTH that requires a gentle flow of air to cool it. This is often blocked with shellac from previously failed windings.
A lot of mag restorers do not clear this - it is a pesky thing to do.
My recent experience with mags is that to get reliability you need a hotter plug D21 - with D16 they start to miss on the overrun - the mag windings then heat up and it then may fail.
I know there is a safety spark earth in the mag that supposedly protects it - these are not very efficient and are rarely correctly adjusted
Since I have adopted this approach i.e. the D21 plugs mags for me are very very reliable.
I am convinced this is a change needed for modern fuel. I am afraid I don't understand why.
Hope this is of some help to you.