Question : would you reuse the aluminum spools when you rebuild the magneto or buy new? I believe you have to settle them a little to get the height anyway so why not still use the old? Just asking,MEL.
Good question. I was planning on cleaning and polishing mine and reusing them on my coil tester build.
Good question. I was planning on cleaning and polishing mine to use them on my coil tester build. I will be watching for responses too.
Personally, if I'm building a fresh engine, I use new ones - you don't need 100 year old aluminum ones that have most likely been "hammered" down to "come from together" at an inopportune time !
For a coil tester - go for it.
Because of age of material; if they are in good shape, no cracks, I would ether adjust height by removing material or buy new ones. They prone to cracking from hitting with dead blow to adjust height. I have reused them, replacing one that were in bad shape. At $1.25 each, cheap insurance. You are better off by ether filing them down to fit or adding shims under to raise up.
Down to my last set of brass ones
I used old ones if they look good and all 16 same size in the caliper
I bought a new spool set and measured their heights.
They were all exactly the same height, so I thought I could just bolt the magnets on and eliminate the trouble of running that measuring tool around to insure they were all the same height.
WRONG AGAIN!
When I tried to use the flywheel, I found .025 differences in the magnet thickness.
Another important detail is to charge the magnets before you attach them to the flywheel.
You can get a much higher charge and hotter Magneto that way.
Re-using old alum. spools requires lots of inspection, as these were cast, and material defects are present. Plus the surfaces where the magnet edges sat are depressed.
The brass ones are a bit better, but still have ridges where the magnets sat.
The new alum. spools are machined of harder grade of alum. and hammering on them is more difficult, so normally grind some of the tops or do the same to the plates, in getting all the magnets to equal height with the gap gage.
I hate the idea of adjusting magnet height by hammering. I make shims to go under the spools where the magnets are low.
I've reused the aluminum ones with no trouble.
Not all magnets/spools/plates are the same thickness. When using the hammer method to true up you will find that one side of the spool may be more crushed then the other, as shown by the photo above. Just adding a shim or removing material will not work all the time but will get in the ball park.
OP I have seen someplace there is an allowance in heights. While 100% is nice, there is a point where if it is a few thousandth off it should not hurt. We are talking about a setup gap of .025 to .040 anyway.
Correct. In a range of .015" between .025" and.040", a variation of .002" or .003" doesn't matter.
I agree with steve getting all 16 polls within .005 between high and lowand i check when istalled level tranny on top and tranny on bottom and .024 to .030 procuces a mag hot enough to start on
Ok, if I take all mine and resurface them so all are flat on the ends and adjusted to whatever the thickness of the thinnest one in the bunch, will they be good to go, possibly with shims?
The spools I was getting from one vendor had up to .015” variance in heights so I had a big batch made that are precision height. I will offer a set of 16 for $20 with FREE SHIPPING anywhere inside the U.S. to anyone here that may want them. Send me a pm if you are interested.
Adam: PM sent, requesting one set and your catalog of parts. Thanks, jb