Author Topic: Alan's Fairy rebuild  (Read 1854 times)

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Offline GlennMckenzie

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Alan's Fairy rebuild
« on: 05 Jul 2018 at 13:20 »
Hi Forum members.
I thought I would share this rebuild with interested forum members as we will need some technical advice along the way.
Alan has been kind enough to assist me multiple times over the years with bits and pieces so I recently offered to repay the favor by helping with the rebuild of his 1907 Fairy Engine.
Stay tuned, I may have questions
Glenn

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #1 on: 05 Jul 2018 at 13:26 »
I CNC machined a new 36 Tooth Camshaft gear, I modified the tooth shape slightly to better match the well worn Crankshaft gear.

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #2 on: 05 Jul 2018 at 13:39 »
The Cam Shaft and Gear cant be one piece unfortunately. Because of the casting overhang inside the crank case the gear has to be fitted after the Camshaft has been inserted.
An internal nut or screw holding the gear onto the Camshaft would destroy the engine if it came loose, so I decided to cut a square spigot on the Gear with a corresponding square pocket in the Cam. The idea is to run a bolt from the outside all the way through to the Cam gear. This bolt would later attached the distributor arm/rotor to the Camshaft (outside the engine). My thinking is, if the bolt ever comes loose the engine will stop because the rotor will stop turning. 

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #3 on: 05 Jul 2018 at 13:48 »
This is where I need some expert advice.
Machining the Cam shape onto the new Camshaft Shaft. 
In relation to the teeth on the Cam Gear, where should the highest point of lift be?
36 teeth will give 10 degree increments of Cam adjustment already, Is this close enough for Cam timing?
Thanks Glenn
« Last Edit: 05 Jul 2018 at 14:29 by GlennMckenzie »

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #4 on: 05 Jul 2018 at 14:10 »
Thoughts please?

Looking at the first photo I posted of Alan's Crankcase.
Im wondering how the ignition Timing/distributor housing is mounted to the front of the Crankcase.
One Idea would be to replace the existing Camshaft Bronze bush with a longer one, the Distributor housing could then rotate on the extended bush to advance and retard the timing.
This photo shows the rough remains of a distributor housing on what looks to me like an extended Camshaft bush?

Thanks Glenn

   

Offline eddie

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Re: Alan's Fairy rebuild
« Reply #5 on: 05 Jul 2018 at 17:12 »
Glenn,
           You asked for our thoughts - I may be wide of the mark, but here goes!
  Firstly, you say the cam and gear have to be separate to insert them into the crankcase - I don't think this is the case. As this engine has automatic inlet valves and is a flat twin, then the camshaft will have just a single lobe that operates both exhaust valves. If this is the case, then the cam and gear can be rotated to a position where it will go into place and then turned to the correct timing position, and then the crankshaft inserted into the crankcase to mesh with the cam to give the correct timing.
   You also mention a distributor. Bearing in mind the age of this engine, it probably had trembler coil ignition - in which case a cam or flat on the end of the camshaft probably operated a make and break for the trembler coil.

  Regards,
                Eddie.

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #6 on: 06 Jul 2018 at 03:53 »
Thanks Eddie,
The Cam slides in past the Crankcase easily as you mentioned. Its the 36 tooth Gear that wont fit.
Interesting video on this site showing the Fairy's trembler ignition in action. I will leave that part for Alan, I'm just machining the missing Engine parts.
I digitized whats left of the original Cam and machined the Profile onto the new Camshaft today.
Glenn
« Last Edit: 06 Jul 2018 at 04:01 by GlennMckenzie »

Offline cardan

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Re: Alan's Fairy rebuild
« Reply #7 on: 06 Jul 2018 at 05:14 »

Having the cam drive gear inside the crankcase is reasonably common on early bikes: here's the setup on my 1903 Bradbury. Note the wiper for trembler coil.

I'm not sure about the original Fairy ignition but 1907-08 is very late for trembler coil, which was poorly behaved at higher revs. An ordinary HT coil would perform better and (other than some notable exceptions like the T Ford!) took over from trembler after after the early 1900s.

Regardless of trembler/induction coil, I assume the Fairy doesn't have a distributor, but instead has a wasted spark.

Cheers

Leon

Offline Hutch

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Re: Alan's Fairy rebuild
« Reply #8 on: 06 Jul 2018 at 07:32 »

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #9 on: 06 Jul 2018 at 08:35 »
Hi Ian,

It does look like the Bronze Camshaft Bearing extends out past the Crankcase. So the timing rotor thingy (I still recon its a distributor) slides over the extended bush.

Perfect thanks.

Offline graeme

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Re: Alan's Fairy rebuild
« Reply #10 on: 15 Jul 2018 at 11:36 »
There is a wipe contact arrangement on the end of the crank, and that has the advance retard. No wasted spark - there is a rocking distributor that fits on the spot at 2 o'clock, and a plunger is pushed by a second cam on the cam wheel. I'd have to pull the engine apart on mine to show what it looks like.
This distributor is what we need the details of from the chap in NZ Glenn

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #11 on: 06 Aug 2018 at 09:36 »
A bit of progress in the last few weeks.

Re-machined the pushrod holes as they were welded over.
Made new pushrod guides.
Machined new cam followers/pushrods from 1/4" Ejector pins and had them heat treated.
CNC milled the small Aluminium cover at the end of the Crankshaft and the new Distributor Housing thing.
1/4" bolt now locks everything together from the rotor back through to the Cam Gear.

Still quite a bit to do cosmetically and mechanically. The engine is missing a lot of fins on rear and I need to look at the inlet valve area as I don't think the Brass bits hanging out the end of the cylinders are original. From what Iv seen in other photos there should be cast Iron plugs screwed in the ends holding the atmospheric inlet valve assemblies in position. As shown in the photo below.
Also, still undecided what to do with ignition. I was thinking of hiding some points inside the Distributor Housing body and running wiring back up to a hidden Battery and coil. Not my preferred option as this would give spark to both Cylinders simultaneously. The other option would be hide some fancy new electronic ignition system somewhere.

Ideas anyone?

Glenn
 

Offline cardan

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Re: Alan's Fairy rebuild
« Reply #12 on: 11 Aug 2018 at 10:13 »

We've discussed the Fairy inlet valves in an earlier thread: http://www.douglasmotorcycles.net/index.php?topic=6560.msg24613#msg24613

On the Fairy, the atmospheric inlet valves live in horizontal cages that are held in place by the hex-head plugs, and the manifold attaches from underneath.

The Fairy distributor is whacky, but interesting!

Cheers

Leon

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #13 on: 09 Nov 2018 at 06:32 »
Hi Forum members,

Its been a while since my last update.
Engine is mechanically finished and I have managed to fit some points I found at Laidley Swap inside the now slightly larger distributor housing. Made an exhaust and replaced all the broken fins. Engine spins over freely and is showing signs of life.

I made a couple of dummy engine mounts out of some fence clamps and roughly fitted the Engine for the first time Today.
The Engine is sitting a bit high at the moment, some shorter mounts will fix that problem.

Glenn

Offline bear640

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Re: Alan's Fairy rebuild
« Reply #14 on: 09 Nov 2018 at 19:35 »
Just out of curiosity Glenn, what’s the other bikes in the background?

Offline RockDr.

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Re: Alan's Fairy rebuild
« Reply #15 on: 10 Nov 2018 at 03:43 »
That's what I was thinking about too. I'm guessing a Triumph P model and perhaps and AJS? It's nice to see them in original patina.

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #16 on: 11 Nov 2018 at 05:49 »
Model N Triumph and 1925 AJS

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #17 on: 21 Nov 2018 at 06:30 »
A little more progress this week.

I machined up a bearing housing block that clamps onto the lower Frame for the idler gear and drive pulley.
Everything is roughly aligned at this stage, waiting for the rear wheel for final alignment.
Left crank pedal arm is hitting the Pulley so I mite have to make a short extension? I don't think a more aggressive bend will do it.

Cheers, Glenn

Offline GlennMckenzie

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Re: Alan's Fairy rebuild
« Reply #18 on: 06 Dec 2018 at 08:13 »
More progress