New spark in her step

[CalGG]

So the old gal was letting me down over the past two days. (E27n Gas). I was just trying to get her situated to her summer accomodations after being on the ready to plow snow all winter. What was planed was to warm her up good, get the oil and what not dried out and spread around etc. But she was having no part of it.

She started up very reluctantly, hmm, not her typical enthusiasm for a bit of frisky. After finally starting and a warm up, she went off OK and I ventured up and down our rural roadway a couple of times. Maybe 7 km total distance ,which in road gear does not take all that long. She was missing a bit from time to time, so I sped up the rpms in hopes of clearing out any winter carbon accumulation. Soon she was purring a top! I made my way to the entrance to the drive up to the house and shed. 'Stopped to shift into 1st (It's a steep incline) and she just up and died, not to restart, hell or high water. A tow chain was the put to use to get her in the yard ;-( Two days of fighting to get started, then running sweet as candy , then dying, not to restart, had me frosted!

Looking to the fuel, everything checked out. Looking to the mag reminded me of all the nagging issues. The Lucas RF4 was getting long of tooth. She always did have a weak and tempermental spark, even after fitting a replacement bobbin sourced from a wreckers to restore the 6200 ohms of windings from the original item which only measures at about 4100 ohms. Must be some windings shorted out in there.
A host of troubles with the mag really. Weak rotor magnet, iffy windings, and an impulse coupling that kicks out at about 20 rpm. Just when the engine is hitting, the spark goes winky. The condenser even proved out entirely open. Fortunately a spare was in the box of available parts, purchased before hand, just for such a situation.
After "reconditioning" the Lucas too many times, I thought I better fit the WICO XH-23 I had purchased so many years ago for just this reason. (It's a wonder the Lucas mag kept working "just well enough" all these years.)

The WICO mag was selected as a best match to the RF 4, but it's not just a bolt up operation. The pad mounting bolts fit righ up, and the center height is a match. The Wico needed a coupling and some sort of sealing arrangement to keep the engine oil from moving through the timing chest and making it's way out past the magneto. A new coupling for the Hooke drive was turned up and milled out of a block of aluminum. A 5/16 slot one way to fit the Fordson timing gear, and a 1/4 inch slot at 90 degrees to fit the WICO impulse coupling . This piece was about three times thicker than the Fordson original piece to accomodate the WICO's shorter length. I guessed about the length while the stock was in the lathe, but got lucky, as only about .025" was required to be removed to fit the parts just right.
The oil sealing piece was a bit of a thought problem. There really is no surface on the WICO to put any threaded fasteners into. (At least not without more intamate knoledge of what lays inside.)

But a simple flange spigot that gets trapped between the sttep bore in the engine housing and the mag face seems to have been a good choice. A fat o-ring that I had made up as replacement for the felt seal fits the application perfectly.
This sealing piece is a very close fit to the coupling, with clearance maintained by the impulse coupling drive dogs.

About four hours machine time, with most of that consumed by "cut and fit" work methods.

This morning, the spark leads were refit with proper end terminals to plug into the WICO mag distributor cap. Forson spec is to shove them in the cap holes, then clich with a pointed screw. Proper dust and moisture boots went on the leads as well. (All these ignition cable parts compliments of a long past Toyota Land Cruiser

Well, Using the flat belt drive pully to hand over the Engine made finding TDC on #1 a simple matter. (Hand crank had to be removed when the snow plow frame was fitted)
1243! A bit of Choke, a twist of the starter knob, a little clack, clack, clack, of the impulse , and... Varoom!

The old gal has new spark!

We went out for a drive around the neighborhood to mark the event. It's such a delightful spring day.

The RF4 is wrapped in protective wrapper and on the "spares" shelf.) A project for some rainy week to rebuild ...again
I think I am going to appreciate the water tight construction of the WICO mag. Because I'm quite sure that heavy spring rain we had last week was the reason for this latest bit of bother, With the plow on, the Fordson does not snuggle back into the small shed quite so far as she does stripped down. Still, It was time for a change.

These tractors take some keeping up!

Cheers

Cal

opps, I better go out and snug up those mag mounting bolts, 9/16 head size. I just ran them in finger tight to see if things were fit right. Then fell to my excitement.

[1949E27N]

Great job Cal, got any photos of the WICO?

I've got a spare RF4, I'd love to know how to test it and rebuild it if it needed. Any tips you can give me? Never done anything like this before but hey you've gotta start somewhere.

Chris

[Dandy Dave]

Sounds about like everything else Lucas Built. Off, Flicker, and Dim.... I can attest that the Wico is a much better mag no matter what it is on. You wont be sorry for the swap. Dandy Dave!

[CalGG]

Chris

I can't speak in generalities regarding Magneto service, the only mag I've ever worked on has been the Lucas RF4 fitted to my E27n. But , I have LOTS of time there
(other than cleaning and setting points on some old CAT equipment or many many years ago, garden equipment excluded! seems like that is an every year ritual)

What I can tell you right off is to check the coil bobbin. If that item is aged and gone, no amount of work on the other parts will amount to any improvement. The solid wire that leads out to the condenser is the testing point, and it needs to be isolated (disconnected) from contact with the condenser or any other part of the mag. Checking resistance between that wire to ground should be greater than 6000 Ohms. More would be nice, but 7K is likely asking too much. (I will be getting my spare bobbin rewound and encapsulated). Oh, And it best NOT to hand turn a magneto whitout shorting the spark to the mag body. The generated voltage wants to go somewhere, and if it finds a way to jump deep inside the windings due to deterioration of the insulation, it will. The arc will make a carbon track that will just lead to further breakdown. So don't casually "hand prop" the impulse coupling just to feel it working

Points and condenser replacements are available from "Old 20" and some others, Rotors and caps too, but the costs add up. That's when a replacement like the WICO just makes sense.
I had chipped and missing rotor gear teeth in mine.

IF you plan a strip down, Get a muffin tin to sort parts as you remove things. KEEP NOTES! and sketches as needed. Be very mindful of the rotor timing and gear orientations. Look for the marks before you take things apart, and then add your own references. The little insulating washers and bits associated with the points are very important to keep right. I lost one of the spacing washers for the points to condensor wire ring. I spent over an hour making up a new on.

The impulse coupling is keyed, on a tapered shaft. Back threading the mounting nut to tension and then a little tap with a brass hammer should pop the coupling off. Remove the key if you intend to slip out the magnet rotor or it will slice the seal.

There are brass shims under the front housing that contains the points etc. These shims set the end play for the mag rotor bearings. Evaluate the condition before removing that housing. A dial indicator set up would be nice, but you could do fine with your sense of feel. Any end play of that main shaft suggests removal of somew shim thickness.
With this housing removed, inspect the distributor rotor, remove it from it's shaft, keeping track of the carbon brush and spring inside. Check the security of the shaft to its insulating mounting block. That assembly can be a very snug fit in it's pocket, but you don't want to stress the metal to bake-o-lite joint, nor chip and crack the bake-o-lite mounting block. This part needs to be arc track free and CLEAN with just a drop of oil on the shaft for the rotor on assembly.Be sure flat spring contact with the winding bobbin on the back side is clean as well.

I always worry about the strength of the rotor magnet. Just taking the rotor out of it's operating field the first time cuts the strength by over 30%. This only happens once, ( a Shark of magnets) If your rotor turns with a decided "kick" as the magnetic field comes in and out of conflict, consider yourself fortunate and don't pull the rotor shaft from the mag! My unit is positively pathetic in this regard, and the pale spark bears witness. If there were a way to get these mags regaussed, that would be a real boon.

And they say the LUCAS Mag is a "simple" instrument

Let me know if I can help, I don't visit this site every day, but I'll check in.

Cheers

Cal

[CalGG]

A useful reference

http://www.sky-net.org.uk/kelvin/tech_i ... f4_manual/

[1949E27N]

Thanks a heap for the information Cal. It certainly gives me a place to start.

Chris