I have an original Allen Coil tester with a Jewell Ampmeter that was recently calibrated and certified, that I am trying to make operational. I have dismantled it, painted each part individually and reassembled it (taking care to scrape the joint points between the parts for full grounding), but when I load in a coil and a spark plug, I can't get a reading. On an Allen coil tester, how far should the magnet plates on the flywheel be from the magneto coil plates? Right now the gap is about 1/16" (.0625). All around. If the gap is supposed to be the same as on the car, I know it is way too much. What is the greatest gap by which a current will be generated before the gap becomes too wide for a current to be created? Thanks. Jim.
Here's another picture. Jim
shim to exact same gap as car.
I have the same coil tester, it took me several attempts with advice from Bob Scherzer and Ron Patterson to get it running right. I am sending you a private message with some lessons I learned.
Hmm, I wonder if that's the same Allen Co. who made my postwar disturbutor tester?
Ford Specs... .025" to .040"
Also, start out with a known GOOD and properly adjusted coil. Makes hunting down the problems eaiser.
Yes it is.
Follow the advice above on the magnet to field pole gap. Also be advised that sparks will not appear at the 1/4 inch spark ring gap when a spark plug is sitting on the spark plug test points.
Ron the Coilman
Ron has a good point both the spark plug gap and the gap on the HCCT pointer to ring gap needs to be fairly close. Also the points on the spark holder, the pointer and the ring all need to be clean and free of paint.
My point was slightly different.
A properly adjusted Model T ignition coil will easily develop a spark which will jump a clean HCCT spark gap of 1/4 inch in free air which is a good test criteria.
The HCCT spark plug test is not comprehensive for the reasons Gary Tilstrom aptly pointed out in his reply to Jon Crane in another post on this Forum.
I fully agree with you on the need to keep the HCCT spark gap clean. Any oxidization of the tip of the spark gap pointer or spark ring will inhibit free (uncompressed) air spark gap ionization of the 1/4 inch gap and will result in the illusion of poor coil performance.
In fact the original booklet Ford included with their coil tester mentioned this point.
Ford HCCT Booklet
Ron the Coilman
Behind the hand crank disk, there is a white cylindrical insulator about 2" long x about 3/8" diameter with a Y type contact consisting of two pronged flat contacts that line up with and run along the ring when the crank is turned. On the other end of the white insulator is a knurled brass knob that turns. This piece was purchased from Bob Scherzer. I installed it, but have no idea what adjustments might be required. Is it supposed to be tight against the ring or is there supposed to be a gap between the contacts and the ring? Where does the gap appear?
Thank you all
Jim or Ron what is the white thing?
Ron thanks for the link to the HCCT book.
The hand cranked coil tester excites the coil from the same magneto found inside the Model T engine.
In the HCCT the high tension output of the coil is fed to the spark ring so you can see if the points are operating correctly. When the HCCT is turned the spark output of the coil which occurs every 22.5 degrees of flywheel rotation is fed to the spark ring so you can visualize the sixteen sparks.
As you can easily see from other Forum posts by Bob Scherzer on this subject the coil spark output of the coil is connected to the inner ring where the two "wings" of the white electrode run. This connects the spark output to the tip of the white electrode. The collar on the outer end of the white electrode is movable and thereby you can adjust the spark gap.
Hope this helps.
Ron the Coilman
I hope this helps to explain the set up of the spark electrode to the slip ring.
The first picture is the way the two relate to each other.
The second picture is the electrode mounted in the front disc. The spark jumps from the knurled brass ring's tip to the disc. The spark gap is set by moving the ring up or down on the insulated part[white part]of the electrode.
The third is the slip ring mounted on the tester. This slip ring must be insulated from the rest of the tester parts. If you check from the bottom/side tab or hot side inside the coil box to the top of the brass knurled ring on the electrode you should have a completed circuit and insulated from all the other parts of the tester. The electrode fingers need to just touch the slip ring. You can bend the fingers in or out to get this contact correct.
The forth picture shows the connection from the coil box to the back of the slip ring.
In your picture it looks like the insulation that holds the slip ring is damage and could be allowing the spark to go to ground rather than being allowed to jump the air gap between the knurled brass ring to the disc.
In the last picture I show a blurred shot in time delay of two sparks jumping the gap on the left side of the disc as they would appear when testing a coil. Of course there would be 16 sparks in total with one revolution of the disc. Bob
I primed and painted my entire crank disk. If the spark jumps from the knurled tip to the disc, it stands to reason that the area around the knurled tip should be bare metal and that being primed and painted prevent the spark from occuring. Am I correct? If so, how far should the bare area extend out from the electrode? Thanks. Jim
You are correct, clean the paint off the crank disc around the electrode, 1/16-1/8" should be fine. You should be able to get a test light to work on the bottom coil holder terminal and the "bat" terminal regardless of the electrode sparking or not. Step 1 get the magneto to produce power, step 2 get the electrode to spark with a known good and adjusted coil, step 3 coil testing and adjusting.
You think you have questions now, wait until it works and you start adjusting coils, you aint seen nothin yet.
I'd like to see a shot of your slip ring assembly since I think you may have a problem there but as already stated you should get some kind of amp meter reading regardless if the magneto is working and you have a decent coil in place.
If you connect a 6 volt light between the two terminal screws at the side of the tester marked "Horn" and "Ground" and crank the tester with or without not coil in place the bulb should light if the magneto is putting out any current. I always recharge the magnets and test the mag coil before assembling to be sure everything is up to snuff.
If your tester is like the ones I reproduced you increase the gap between the mag coil and flywheel magnets by adding shims to the shaft and decrease the gap by removing shims. If your gap is too wide then you may need to remove a couple. You can also decrease the gap by adding shims to the mag coil but that's more involved and I only add shims there when getting the mag coil parallel to the magnets if needed.
I made up these donut shims .008 in thickness. Starting out I add about 4 and then check for gap. Then add or remove one until the magnets just start to touch then add one back to get a closer then normal gap of .025. This just allows for a stronger current flow at a slower cranking speed. The main purpose is to get and maintain 5 to 6 volts at a good cranking speed. Normally a T coil will start to spark at 2 volts if it has been set up correctly and so cranking speeds can be done at a easier pace.
And if you want to doll up your tester I also make copies of wooden crank handle like original used on the Allens using either cherry or hard maple for the wood. Bob
Good morning, Bob.
Currently, the gap between the flywheel magnet plates and mag coils is 1/16" (.0625). Yesterday, I ordered four .0625 laminated brass shims from McMaster Carr which should arrive today. Hopefully, when I reduce the gap to .025 or so, I will see some current. In your opinion, is it possible that a 1/16" gap is so wide that it could prevent any electricity being produced by the interaction of the magnets and the coils?
I read somewhere that the magnets should be able to hold 3 lbs. Mine will not even hold a spark plug. Could it be that my magnets are too weak and need recharging? If so, how can that be accomplished on the coil tester?
The metal ring is well insulated from the tester frame by a hard fiber insulation plate. I can see no point where there is a remote possibility that it could be grounding itself anywhere on the frame, but I will take the disc off and, later on today, will post a picture of the inside of the disc as well as a picture of the ring.
Thanks again, Bob.
Bob, Here are the pictures of the disc, your electrode and the ring you requested. Jim Jim
With my regular job, a new young wife and family to raise, rental properties to maintain and a lack of space to keep it, I have decided to put this Allen Coil Tester up on ebay tonight (Thursday, 2/22/09), for someone else to benefit from. Also, with only two Model T's in my fleet, I don't have enough coils to adjust to make this a worthwhile investment for me, so, I will leaving it to the experts (hear that Ron?) to adjust my coils for me. I hope someone here wins it so it will be of use to someone in our membership. Good luck and thanks to all of you who offered advice. Jim Patrick
Allen Coil tester is on ebay if you want to check it out. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=110340093372&sspag ename=STRK%3AMESELX%3AIT&viewitem=