OK, so I have this lovely old magneto and a set of Indian-built 500 Bullet crankcases which, unlike their Redditch forebears, were not intended for magneto ignition, they swapped to battery and coil ignition, with the contact breaker drive assembly or “distributor”, if you must, bolted directly to the back of the crankcase.
Now if you wanted to fit a Lucas SR1 magneto on a pre-EFI Indian Bullet, you could bolt one straight on in place of the “distributor”, it would just need the external auto-advance unit to fit it.
However, how do you fit a platform magneto rather than a flange-mounted magneto to a set of Bullet crankcases with no magneto platform? Well, if you’re Grumbern, you set the crankcases up in a milling machine and make a surface flat enough for a platform, I refer you to the Project Laubfrosch if you want to see how an expert does it.
https://forum.classicmotorworks.com/index.php?topic=27215.0I don’t have a milling machine. Is there some other way? Yes, I think so.
Let’s start with a 90° chunk of alumin(i)um angle, 4”x4”x4”. I need to bevel the corner a little.
Now I have already used the finger sander to flatten the crankcase joint a bit, but this is not a precision instrument (as if I had any), we need to see how much more work needs to be done. Now if I coat the top of the oil tank with some engineer’s blue, I can keep the angle with the vertical pressed against the machined face on the back of the crankcase, and by scraping the horizontal edge along the top I can see where the reamining high spots are.
Hmm, that’s not very flat. Pass me the scraper. A bit of work and another pass of the “L” and there’s a teeny bit more flat surface! This is not a quick job…
Eventually it gets to the stage where there’s enough flat surface on to pf the oil tank to change technique, so I can wrap some coarse wet-and-dry around the base of the angle and give it some welly.
Keep at it, and a larger recognizable flat surface starts to appear. Ah-ha!
After a while, it should be possible for the mag to sit square on top of the oil tank with the back of the mag true against the back of the crankcase. Is it? Does it? Yes and yes.
There's still a fair bit to do, I haven't finished with that piece of alimun(i)um angle yet.
Don't worry about stuff finding its way into the oil tank through the breather union hole, by the way, the cases will all be stripped down and cleaned.
A.