[Farmall] Another O-12 project, part 8

[Rob]

Nice writeup Karl!

BTW, I drove by your place the other day. Nice collection by the back fence. I'd still like to get my hands on one of those cute little crawlers some day. Like I don't have enough on my plate already LOL!

Rob
--
'06 Jeep Commander 
'64 Chrysler 300 
'64 Chrysler New Yorker 
'66 Chrysler Town & Country 
'49 Caterpillar 112 Motorgrader 
'47 Farmall "H" 
Ridgecrest Ca. 
Merlins are cool, but 
Radials rule! 
Jets just make noise 

http://www.picturetrail.com/64chrys 
ler300 
http://autos.groups.yahoo.com/group 
/BOGparts/ 



-------------- Original message from Karl Olmstead <kolmstead4 at msn.com>: -------------- 


> Spent a lot of time this past weekend on other projects. Used my Kubota backhoe to dig up a leaky water line on a property I'm developing. Found that the 1.25" line had pulled apart at a glued joint. Don't know the cause; bad glue, improper installation, or just bad luck. Leaky water lines aren't difficult to 
> locate in the Mojave desert; just look for the lush growth of weeds. 
> In keeping with my plan to process x-12 tractor parts in batches, I disassembled ten F4 magnetos. I have about 50 of them, some taken from F-12s I've acquired, many purchased at the Tulare, CA swapmeet; more bought from ebay auctions. I discovered that if an ebay seller has one F4, he or she probably has two or 
> three more that he/she would be happy to sell as one bunch. 
> Back when I first started rebuilding magnetos, I selected the worst ones in my collection, in particular the ones without distributor caps. Sitting open to the weather is really hard on magnetos. By restoring the worst ones first, I 
> reduced the risk of damaging a good magneto while I was learning to work on 
> them. And the tricks I learned then make working on better magnetos a 'piece of 
> cake'. 
> 
> Arbitrarily selected eight F4s with the 'conventional' impulse, and two with the 
> E4A automatic impulse. The two types are incompatible; those with E4A automatic 
> impulse are about half an inch longer than normal F4s. That early O-12 I bought 
> last fall really should have a magneto with the E4A impulse on it. The fact 
> that it doesn't tells me that somebody has changed the magneto mounting bracket. 
> My '31 T-20 uses the early F4 also. It came to me with a Fairbanks-Morse 
> magneto, but I replaced it with a rebuilt F4. 
> 
> I haven't done much magneto work for three or four years, and the first one I 
> dismantled had the E4A impulse, so it took me an hour or more to get it torn 
> down. 
> After that, I remembered the process, and the rest took half an hour or less 
> apiece. Except for one. As soon as I examined it, I expected problems. It was 
> caked with mud. It had obviously spent time in the dirt, probably in a mud 
> puddle. I tried scraping mud off the screw heads with a screwdriver, but that 
> took too long. So I carried the muddy mag over to my sandblast cabinet and 
> blasted the mud and grease off the screw heads. With the screw heads exposed 
> and slots clean, all but one of the screws came out, although it took a LOT of 
> force. Half of one screw head snapped off. I've found two ways to cope with 
> this. You can knock off the other half of the screw head using a hammer and 
> chisel, or try grabbing the screw head with a pliers and unscrewing it. In this 
> case, the pliers worked fine. 
> 
> The magneto drive disk, which is a free-floating disk that couples the dogs on 
> the magneto impulse to the dogs on the engine magneto drive, was stuck hard to 
> the impulse. I sandblasted it, oiled it, and pried it off. The impulse parts 
> that hold the impulse spring were rusted together, so I pried them apart and 
> tried to remove the spring. It broke as I pulled it out; rusted almost through. 
> 
> Cleaned up the points cup and oiled it well; put the points cover back on and 
> beat on the lever with a dead-blow hammer. The cup freed up and I got it out. 
> The magneto rotor was stuck to the case. Sandblasted the crud out, then pressed 
> the rotor out using a hydraulic press. 
> 
> Net result was a good case, good distributor disk and magneto housing, but 
> worthless rotor, gear, bearings and points. Still a fun project! This just 
> happened to be F4 magneto number 140,000, so I wanted to salvage it just for its 
> unusual serial number. 
> 
> Tonight I sorted out the bucket of parts I had accumulated. Magneto coils in 
> one plastic bowl, distributor rotor assemblies in a coffee can, impulse parts in 
> another coffee can, electrical parts in a plastic bowl, all bearings and related 
> parts in another bowl. Decided to test the coils before wasting any time 
> cleaning them up. to my surprise, eight out of ten coils were good, based on 
> resistance measurements. The primary winding resistance should be from 0.2 to 
> 0.4 Ohms; the secondary around 12,500 Ohms. Removed the soft iron core from the 
> two bad coils, then threw the coils away. New coils don't include cores, so you 
> need to keep the old ones. Past experience has shown that about half the coils 
> are bad, so 80% good on this batch was good news. I'll bet coils cost $75 or 
> more nowdays. 
> 
> I've been using diesel fuel in an ultrasonic cleaner to clean up parts. It 
> doesn't work very well. Hope NAPA still sells those hydroseal carburetor 
> cleaning baths. Expensive, but very effective. I'm thinking that diesel fuel 
> in the ultrasonic bath may do good things to the rusted up impulse parts. Can't 
> hurt to try. 
> 
> Anyway, the net result is that I am still accumulating parts to clean and paint. 
> Still need to do a bunch of carburetors. Once I get enough parts primed, I'll 
> start topcoat painting. I don't have much hope that I'll have this particular 
> O-12 running for the Tulare antique tractor show, only one month away. I could 
> have done it if I was willing to fix up just one magneto, carburetor and fuel 
> pump for that tractor, but once I decided to do a whole bunch of each component, 
> I started falling behind schedule. 
> 
> I think that I've figured out how to fix up the rusty round spoke front wheels. 
> I needle scaled one of them a week or two ago, but the original rubber covering 
> the inner end of the spokes was a problem. I think I can rip it off with a big 
> hand-held angle grinder equipped with a wire wheel. 
> 
> 
> -Karl 
> 
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