Author Topic: Vintage Sparks (Read 3343 times)

Adrian II · **on:** November 05, 2020, 12:25:11 pm

After a bit of respite, the magneto madness has struck again, this time a lovely pre-war BTH K type showed up on ebay.

(Note: seller's pictures from ebay)

Off to the garage to see how well or badly it fits an Indian-built iron barrel bottom end, AVL top end thrown on for looks.

It seems to fit pretty well, no larger than a Lucas SR1 or magdyno on the Redditch models, so it will just need the usual carburetor spacer, I don't think there will be too much problem lining it up for the drive pinion or getting it securely fixed, the slots for the magneto strap are still there on Indian Bullets, though having seen the work on Grumbern's Project Laubfrosch, i think a little light milling on top of the oil tank might be needed.

The thing still puts out some reasonable sparks, too, though an overhaul might be a wise precaution. The older style manual advance and retard also still works, it just needs a top bracket along the top of the front bearing housing to fit the cable.

A.

grumbern · **Reply #1 on:** November 05, 2020, 04:18:48 pm

You could make a bracket that goes under the top rear (5/16") oiltank stud to hold the cable, like an "L" shape.
Or even attach one to the cylinder head steady lug on the frame. This would require quite a bit of open running wire though.
Keep posting updates please. There are many ways to success and I'm excited to see which one you will choose

Adrian II · **Reply #2 on:** November 05, 2020, 09:03:58 pm

When the magneto was originally fitted to the Spagforth Whippet or whatever, there would be a simple 2D bracket mounted to the top of the front bearing housing, which is drilled and tapped 4(?)BA to suit. The outer end of the bracket would have curved round slightly and been drilled and tapped at the outer end for the advance/retard cable's threaded adjuster. This would have kept the bare length of inner cable to a er... bare minimum.

The alternative would be to use the later type of manual advance end housing for the bearing and the points with the internal mechanism, as used on the KC1 mag on my other project.

A.

Adrian II · **Reply #3 on:** November 20, 2020, 11:57:07 pm

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=27215.0

I 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.

heloego · **Reply #4 on:** November 21, 2020, 06:06:07 am

Coming along nicely, Adrian!Keep the pics coming!

grumbern · **Reply #5 on:** November 21, 2020, 08:26:48 am

Ok Adrian, now I understand!

Well, this is a possibility. It might take some time, filing, scraping and sanding, but will do as well!
It seems to me the 500 cases are much straighter/flatter than the 350 one I had, where I had to remove ~3mm of material to achieve a right angle!
Keep up the good work! Maybe I will be able to fire mine up for the first time soon. Let's see who's first!

Andreas

Adrian II · **Reply #6 on:** November 21, 2020, 10:53:59 am

You will be first, this is a bit of a side project, yet another distraction from getting my other ones finished!

A.

grumbern · **Reply #7 on:** November 21, 2020, 11:13:10 am

If you're a gearhead, less then three projects at the same time counts as boredom

I have about five right now, three being motorcycles...

Bilgemaster · **Reply #8 on:** November 21, 2020, 04:21:42 pm

I really like that B-TH logo. It sort of reminds me of those ancient coins from Syracuse in Sicily with the dolphins.

Syracuse was also big on that triskelion three-legged symbol, still used on the Sicilian arms, but also by the Isle of Man, of TT motorcycle racing fame...

Adrian II · **Reply #9 on:** November 21, 2020, 08:24:35 pm

The next dolphin-watching cruise departs in half an hour...

A.

Adrian II · **Reply #10 on:** November 21, 2020, 09:16:06 pm

Careful with those curly bits!

AzCal Retred · **Reply #11 on:** November 21, 2020, 09:49:17 pm

The Procter & Gamble pic with "horns" & "inverted 666" reminded me of the pretzel logic displayed by an anti-vaxxer I overheard in line at the hardware store today. He was banging on about Luciferase being in the C19 vaccine and being used to "mark" people. "Are you a Christian? Why, that's the "Mark of the Beast"". Too much Fox Noise & internet time. Vaccines aren't all bad - after all virtually everyone in my parents generation knew someone that suffered from polio. It's a welcome change to be in a forum where everyone knows that the physical universe is completely indifferent to your wordplay...

https://www.tmc.edu/news/2020/07/fireflies-help-kindle-new-tests-and-treatments-for-covid-19/

Bilgemaster · **Reply #12 on:** November 22, 2020, 05:42:08 am

Sweet Baby Jeebus, they had to call it LUCIFERase? Why not Satanade? I had thought of immunologists as generally being fairly bright folks, but that's pretty dumb. Or maybe they really are trying to cull the herd.

Adrian II · **Reply #13 on:** November 22, 2020, 08:23:38 am

https://en.wikipedia.org/wiki/Luciferase

That name will surely feed the conspiracy theories. I'd better post some more on topic content soon!

A.

grumbern · **Reply #14 on:** November 22, 2020, 06:04:43 pm

Pretzel logic - what a phrase! I'll instandly add this to my vocabulary!

Funny thing though about the Pretzel itself: In German it is written with a "B" instead of the "P". I don't know why, maybe Americans wanted it to sound even more German than it does? Ok, enough linguistics, on with ignition...

Adrian II · **Reply #15 on:** November 22, 2020, 10:19:58 pm

It was a Steely Dan album!

https://www.youtube.com/watch?v=sCMpKS77qn8

Back to the mag fitting.

It's all got to be right in 3D. X, Y and Z axis? With the Mag now butting properly against the back of the timing chest, that just leaves the X and Y co-ordinates to sort out.

I need that piece of alumin(i)um back again, break out the engineer's war paint, I have some marking up to do!

A little while later...

No, it's not the mag platform as such, there's a bit still on order, all all will become clear, but until then I can check how accurately I have drilled some of the holes.

The mag looks like this underneath, holes are ⅜" BSW, but on 50mm centers.

Lookin' good! Those bolts will feature again in a while.

A.

Adrian II · **Reply #16 on:** December 03, 2020, 10:45:16 pm

Some progress to report on the magneto front.

The missing piece of alloy arrived.

41mm O/D which is near enough for my ham-fisted standards to 1⅝". I'll come back to that later.

Just a reminder, for an easy fit, a platform magneto needs a magneto platform, and older Redditch Bullets have THIS:

While my crankcases were left looking like THIS:

So what's with the aluminum disk? Clue:

so bolting this to the back of the angle piece with the holes carefully drilled to match the base of the magneto has the disk bolted to the back...

gives me a jig for drilling holes for the magneto mounting pegs!

So once is has been leveled up with a piece of 1/8" alloy plate and with the back held against the back of the timing cover I should be able to use it to drill holes for the locating pegs in exactly the right place, yes? Or three of them, at least.

Still waiting for the alloy plug for the breather vent, that will be fitted, loctited, leveled and drilled in due course.

That 1/8" alloy plate looked like it might be just right for the spacer plate, so it was trimmed and drilled to suit.

Now I need some locating pegs, hand me those ⅜"Whitworth bolts.

So with three out of four pegs screwed in and the spacer plate on, HOW WELL DOES IT FIT?!?

Hey, that's really close! The magneto sits steady on the top of the oil tank and square to the back of the timing chest. Now as I'm claiming anything but precision in my work and methods, I was not surprised that there was a bit too much slop/lash between the mag pinion and the idler gear teeth with the 1/8" (3.imm) alloy plate, but I can fix that. I have another chunk of alloy plate 2.3mm (11 gauge?) thick, I tried a piece under the magneto and the lash is now within acceptable limits. It might improve further when I fit new bronze bushes to the idler pinions!

I think I can call that a success.

Next job, after sorting out the blanking plug, will be to see if I can follow Grumbern's method of re-purposing exhaust clamps for magneto straps, I will need some slightly shorter ones.

A.

enfieldnewbe · **Reply #17 on:** December 04, 2020, 08:26:47 am

looks good , is it turning in the right direction for the BTH ?

Adrian II · **Reply #18 on:** December 04, 2020, 10:49:43 am

Yes, this one has a nice big anti-clockwise arrow engraved on the back, and the right size taper with the ⅜" BSF male thread too. I always check this when an interesting BTH comes up fro sale.

A.

enfieldnewbe · **Reply #19 on:** December 04, 2020, 11:15:53 am

just done the same to the panther engine (lucas) wasted spark at engine speed .

Adrian II · **Reply #20 on:** December 04, 2020, 01:21:32 pm

The wasted spark doesn't seem to do the more recent Indian-built Bullets with crankshaft-mounted ignition any harm. An engine-speed magneto will give you a fatter spark for kicking over, possibly!

A.

enfieldnewbe · **Reply #21 on:** December 04, 2020, 03:32:10 pm

worked for panther also , just need to watch the carb just in case of fire , its only happened once on my 33 panther , i think they needed to spin the dynamo as fast as they could to get any charge .

grumbern · **Reply #22 on:** December 05, 2020, 09:59:23 pm

This looks very good, Adrian!

Adrian II · **Reply #23 on:** December 05, 2020, 11:02:38 pm

Apart from the sorting out the strap I also need to make a replacement arm for the advance/retard cable.

A.

enfieldnewbe · **Reply #24 on:** December 06, 2020, 10:54:31 am

is the arm also the cam ring on this mag ? are you in the uk , i may have one

Adrian II · **Reply #25 on:** December 06, 2020, 04:37:00 pm

Hi,

yes I am in the UK, New Forest (-ish).

The missing piece is shown on top of the points housing/bearing end plate on this possibly earlier K1 BTH, which has just come up on eBay UK (item 224265730259 in case anyone here wants to fit one!). I had planned to a replacement arm out of a chunk of 3mm steel, though if you do have spare one handy, I'd be interested.

A.

heloego · **Reply #26 on:** December 07, 2020, 10:03:51 pm

Excellent work, Adrian!

Adrian II · **Reply #27 on:** December 08, 2020, 11:49:31 am

And it will be nicely incongruous with the VM38 Mikuni.

A.