1/4-26 un? why?

[mark]

I took the starter apart to freshen it up... prior to cranking/starting a 100E engine that has been sitting 3 decades. The brass stud had some burn/melted marks on it, (from jumper cables)...making it hard to get its brass nut off. So I mic'd the dia (1/4") and I could tell it was a fine thread...thus...I got out my 1/4-28 die. It threaded on easily the thickness of the die and stopped. So I took a wrench and wrenched it. By halfway, I noticed too many brass chips are appearing. My first thought was how did it cross thread! It screwed on easily by hand the thickness of the die!
Further investigating reveals it is a 1/4-26. Has anyone ever heard of a 1/4-26?
Looking at the pics, the left half of the stud is not touched. The right half is my 1/4-28 die work. I stopped the die half way and you can see the threads buggered up a little in the middle at the transition point.
27 TPI doesn't line up, 28 is even worse. But the 26 TPI lines up.
So I guess I will use a 1/4-28 nut and use washer to fill in the center transition. The 1/4-28 nut is now a little loose, so I might make a double thick nut to help keep from stripping the fragile stud threads.
Anyone ever pick up on this anomaly while working on their starter?

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[mark]

I just googled it and according to wiki, it is a British Standard Brass thread. I wont explain it here, you can go to wiki to read it, but apparently they used 26 TPI for 1/8" to 2" brass diameters.

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

[JAN]

There were all sorts of weird and wonderful thread types in the good old days with each trade having its own, e.g. plumbers had pipe thread, electrical, cycle, to name but a few. Most motor manufacturers originally used Whitworth threads before settling on Imperial (identical to S.A.E.). Now it's all metric, of course. I think these were BA (British Association), with 25.4 t.p.i. Many smaller brass components used those threads. You get pipe threads with such things as temperature senders and hose connections.

[mark]

thanks Jan, I remember a special thread on the top screw (I think) on the headlight bezel too. And maybe the tail light lense?

I thought I would show what I am working on. I am not sure why I want to see this motor run again, as I have no plans for it. I guess it is just the challenge (or fondness) of these little engines. The engine sits in a homemade frame and was going to be a homebuilt tractor which was never completed. after more than 30 years of sitting outdoors and under tarps, I believe it will run. It turns over, oil looks fresh (changeg it anyway), borescope in the plug holes show no rust on the valves (can't see cylinder walls) . I did put oil in the cylinders about 20 years and sealed up the exhaust and carburetor in attempt to preserve this little beast. I installed new oil filter, new plugs, cleaned the carb, went thru the distributor and starter. You can see the wide brass nut I made for the starter lug...to fix the threads I messed up. It has a counter bore to clear the 26 TPI and engage only on the 28 TPI I created. Also made a cover for the brush access holes on the starter.
I hope to put add some gas and hook up a defibrillator (jumper cables) in the coming days and bring some life back into her.

does anyone have extra distributor spark plug wire nuts (threaded type) and the brass washer for the copper wire? I need 3 each.
I may 3d print these or machine them out of plastic material...but before I do, I thought I would check with the fine folks here.
thanks

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[JAN]

I don't think plastic will work; they were metal for a reason. They have to conduct the HT current and plastic won't be helpful here. I know that that the spark can and does jump a couple of gaps but this would add to the resistance and demand a higher voltage output from the coil.

[peteleo]

Mark,

I have spare dist wire nuts for the cap plus wires washers. PM me your address.

Pete

[mark]

thanks Jan... but maybe I got the words a little mixed up?
Which part are you referring is made out of steel? Is nut even the correct word? they dont have internal threads...lol.
I was referring to the "nuts" could be made out of a plastic like material (maybe like bakelite). These nuts have an odd thread too. It measures to be 1/2"-16. A hardware store might have the brass washer.

Peteleo...a pm sent

update..
I took some generic plug wires, bent the brass connector so it would slide onto the brass distributor post and the plug wire rubber boot is holding it down for the time being. Filled the carburetor bowl with gas and hit the starter with the defibrillator (jumper cables). She coughed up some heavy smoke for a few seconds (from the oil filled cylinders). and died. I filled the carb bowl up again, and this time the little beast (or runt) came to life. She idled perfectly for minute or so until the bowl went dry. I think she is a runner!
Now I have to find the fan and a belt and get the cooling system going.
So glad she was not seized up after 30 years outdoors under a tattered tarp! I might even have to find a body for her!

[mark]

peteleo,
it turns out I have short and long. I think either will work. the long one bottoms out on the coil hole and the plug holes at the same time. With about 3 threads left over...this is the difference in length too. So adding the wire and the washer it looks like short one will work as well without issue.
Could they have had different distributor caps back then? or did they really have 4 of one length and one a different length for the coil hole? just curious!
Note: the short one is not broke off...it has the smooth and rounded radius on that end, just like the long one.

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[peteleo]

Hi Mark,

PM sent. I included my email so I can send photos.
Yes, there are two lengths of ignition wire tie-down nuts depending on cap manufacturer.

[peteleo]

Hi Mark,

PM sent

[peteleo]

Hi Mark,

PM sent. There are two lengths of nuts depending on cap manufacturer.
I would use the longer nuts to be save.

Pete

[peteleo]

Sorry for all those unnecessary replies. Each time I submit it came across " invalid ".

[mark]

I have messages too that something didnt work , but then it shows up just fine.

[JAN]

I did reply but it seems to have vanished into the ether! Anyway, over here they are referred to as acorn nuts. The long one goes in the coil and the short ones to the distributor.

[mark]

lol...Jan I saw it under another post about the diff ratios. I saw it because I use the "new posts" filter. my apologies for not letting you know!

update:
I found a 12 volt ford generator with regulator in my junk . I think I might weld up something to mount it to the existing bracket on the engine. Then get a belt to fit and and run it up to temp to see if it is going to smoke (both engine and generator... lol).
I have an electric fuel pump I can also add to it so I dont have to fill the bowl by hand. (Part of the existing fuel pump is missing.)