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RE: Blic magneto - no discernible difference when advancing or retarding... - stuartu - 06-04-2021
Ruairidh,
There are comments and instructions about the internal timing of magnetos here
https://www.themagnetoguys.co.uk/reversing-direction---magnetos
you will need to scroll down a fair way to find the relevant section.
Does the Blic in question have a fibre cam? Reducing the matter to absurdity, if the cam were almost a cylinder with just enough lift to separate the points I would think that you might find the position of the advance and retard lever had less effect - there would be a weak spark everywhere you put it. I speak in ignorance but I wonder if the problem is a worn cam?
Regards,
Stuart
RE: Blic magneto - no discernible difference when advancing or retarding... - David Cochrane - 06-04-2021
If I remember correctly (not having a BLIC handy to look at) I think it has a metal cam.
RE: Blic magneto - no discernible difference when advancing or retarding... - Robert Leigh - 06-04-2021
You are correct, David.
RE: Blic magneto - no discernible difference when advancing or retarding... - Robin Boyce - 06-04-2021
The arm that came with the car and a BLIC mag works well with a Scintilla, both responding as required. Don't know which length, but very little movement on the quadrant is needed, so perhaps the long one.
RE: Blic magneto - no discernible difference when advancing or retarding... - Robert Foreman - 06-04-2021
On a BLIC magneto if it has standard points then the cam is steel. If it has high speed points then the cam is made of fibre.
The longer advance and retard arm was for the BLIC and ML magneto and the two end holes are 1⅝" centres.
RE: Blic magneto - no discernible difference when advancing or retarding... - Colin Morgan - 06-04-2021
Hi - What happens if you swap the magnetos?
RE: Blic magneto - no discernible difference when advancing or retarding... - Ruairidh Dunford - 06-04-2021
Alan, I think you are on the money with your comment, thank you.
With help from Robert, his very old magneto book and WhatsApp, I think I have discovered a miss-time inside.
Armature gap at 2.8mm before adjustment...
After one tooth adjustment...
With the single dot aligned the timing hole for the pin now also aligns perfectly - which it did not do before.
I will refit tomorrow and report back, fingers crossed and many thanks for everyone’s input so far.
RE: Blic magneto - no discernible difference when advancing or retarding... - Ruairidh Dunford - 07-04-2021
Well, ding-dong-a-rama, baby!
The engine sings, at last, and runs as I had hoped it would - for the first time.
Thanks for everyone who helped, particularly Robert. I now know how to internally time a BLIC magneto!
RE: Blic magneto - no discernible difference when advancing or retarding... - Colin Morgan - 07-04-2021
That's good. I now understand this too, thanks.
The cam on mine is fibre. There are no dots on the gear, just two or three lightly scribed marks. The points open just as the holes line up - so this is perhaps correct - it has not been tried on a car for a while as I decided to use a BTH in better condition instead.