Does anyone know how accurate the jig is that is listed in the "Model T Ford Club of America - The Electrical System" book on page 48, figure 5?
According to this book, on page 46, it states that "the original capacitors were listed at being 2 to 3 mfd at an unknown voltage, but most checked have been closer to 1 to 2 mfd." Now when I check my original coil, separating the points to check the capacitor, it checked to be 1.4 mfd. So does that mean the capacitor is good? Another checked to be 0.87, that is a KW.
Where is the tar obtained now days to fill back in around the replaced capacitors (other than recycling the old stuff)?
Thank you for your help!
The recommended capacitor value for 1913-1927 Ford and KW coils is 0.47uF capacitor, 400VDC and high ripple current rating (dv/dt >= 600V/us) Lang's has them.
Just a bit of info for you Bryce: Some of us, when replacing the capacitor, fill most of the now empty space with bits of cut-to fit wood. It requires a heck of a lot less tar. You might, as I have, get away with re-using what you removed and have plenty to do the job to boot without buying 10 Lbs (or whatever) of tar which will lay around forever.
Keep the glass insulator in there and is Charles suggested to use some pieces of wood to position your capacitor. Always use tar to repot your coils. They lasted this long with tar the last a lot longer with tar. Others have used silicon compounds and other things to stuff in the Box. Compounds in the silicone sealant will eventually corrode the wires.
RE silicone and is a real pain in the a** to remove if more work is done later!
Bryce, find a local roofing company and ask them for some loose chunks of Type III Steep they might have laying around. If you take along an ignition coil and show them why you need the tar they may be more inclined to help you. Offering to donate to their coffee pot fund helps too. I managed to get myself more than I'll use in my lifetime doing this.
A few years ago, I asked where to get some tar and found a local roofing company that would sell some.
There was a catch though the minimum sale was a 100 pound barrel and it was almost $100 then.
It was produced in Canada and may be cheaper there.
Type 3 was only required later for the Ford tractor and a 1926-27 engine, due to the extra heat that caused hot tar to run out of the coils.
The following chart outlines the bitumens in use today and the range of softening points versus slope:
BITUMEN SOFTENING POINT RECOMMENDED MAXIMUM SLOPE
Asphalt Type I 135-151 Up to 1/2" per foot
Asphalt Type II 158-176 1/2" to 1-1/2" per foot
Asphalt Type III 185-205 1" to 3" per foot
Coal-tar Bitumen 133-147 Up to 1/2" per foot
(EVT) All roofing bitumens have a specific temperature at which they achieve the optimum viscosity for mopping onto the roof. This temperature is called the equiviscous temperature (EVT). Asphalt bitumen manufacturers are currently printing the EVT on their containers. The practical working range for all bitumen types is EVT ± 25° F.
A Tar Barrel.
Here is the picture from the book, I am sorry it took me so long to upload, I was having trouble resizing it. Hope it uploads large enough to view! Any help appreciated.
Thank you all for the information, I am going to read this in the evening and get back to you all if I have more questions.
Thank you! Levi
The "Coil Checking Fixture" depicted in the MTFCA manual is basically a go/no go tester.
It cannot be used to adjust coils to prevent multiple sparking. It is also desirable to set each coil for equal firing time, which this simple tester is incapable of.
It can be used to set the coil to draw 1.3A, and the engine will run, but not necessarily as well as it could, when the coils are adjusted properly.
Dow Corning is making "new type" of low odor tar called "tru-lo" It is available almost everywhere in type 3 steep roof asphalt. Type 4 will work too in a T coil but avoid the type 1 and 2 which are more commonly used on flat roof or mild slope roofs. The larger the "type" number the higher the melting point but tru-lo only emits a high odor if overheated. I like it and used it for all of my last batch of coils. It was not more expensive and if you do need to buy it then make up a business name and march into a roofing supply joint and tell them you have a customer who is making you do something you do not ordinarily do and they are a good customer for the remodeling jobs you do for them. They will sell you the stuff at about 35-50 per "keg" which is what the 100 lb container is called in the trade. Wear old clothes when you go there and play really dumb and they will sell it to you so long as you don't try to skip the sales tax. If they try to charge you a higher price act surprised and tell them "that sounds like an out-of-towner price" and just stare at them and they will usually give in first and charge you the jobber price. Better yet just climb in your T and drive to a rooing place and park where they can see your car. Walk in and ask for help and you will very likely walk out with a big free chunk of tar. Type 3 is what they will have most likely. Bring a sealed cardboard box to put it in or you will have it all over your T upholstery.
Beware when you start to pick the tar out of a coil. If it comes out really easy in big chunks then you are working on an early coil with the low melting point tar that was used well before 1925. If you put that coil into a 26/27 coil box or Fordson tractor you will find tar all over the inside of the box. You can melt out all of the tar in that box using an oven and replace it with type 3 asphalt but be very very careful when picking away the large EASY to REMOVE chunks since the large globs of tar falling off will easily tear the thin paper wrapper on the coil and thus expose the winding. If that happens you best not try to put it back or use anything to wrap it back up since the coil will fail when you pour the hot type 3 tar in there. Since I could not control what car my coils were going into, I always melted out ALL of the tar in old box coils and replaced it with type 3 in any new coil boxes I made.
If you are married and want to stay married you might want to skip the tar melting job all together and do it at a friends house. Make sure his wife is not around either. Ideally keeping the guy as a friend should be optional.
Have fun and always have a large pan of cold water nearby when melting tar and always wear long sleeve shirt and heavy gloves. It burns and it stinks. Tru-lo is really way less stink unless you overheat it which is evident by its beginning to smoke a TON.
Lot of good info there from John and I'll add some that I've found useful: First off I try, and usually succeed, in removing the wood side of the box that the cap is on. Passing a putty knife between the tar and wood usually frees it and it can be carefully pried off. SO much easier to do the job this way. As mentioned leave the glass insulator in place. Avoids winding damage. As to tar: with wood spacers I usually have enough from what I pulled out to complete the job. I melt the tar in a small metal can (soup or whatever) using a vice grip for a handle and a propane torch for heat. Bend a spout in the can. Before heating please. Done outside of course because it stinks like hell
Charlie:::: Chicken soup for coils ???? That's refreshing in the cold weather we're having .... LOL !!! No shoveling, let maintenance work.
I bought this 50 lb block of Type 3 roofing asphalt for around $25., if memory services me. One thing I've discovered is that it's a lot easier to chip off chunks for melting when the temperature is cold.
Hello Bryce I believe back in the late 60s in the MTFCA there was plans to make a coil tester from and old coil box, Dad made one and we have used it ever since. It must work well our stock 1912 T will do 50 MPH all day , the only question is how fast do you want to drive on 100 year old hickery. I will try and find the acticle Cheers Colin