By Ron Patterson
(This article was originally published in the September, 2001 issue of the Spark Coil.)
Lets discuss the coil points that are available new today and cost about $5 a set. I’ll bet you thought you just mount the points and they will work fine, right? Wrong! There are several problems that need to be addressed before you can effectively use them.
1.) Before doing anything clean both parts of the set by rinsing them thoroughly in new lacquer thinner in a small jar with a lid. Carefully shake the jar to make sure the thinner flows through the space under the cushioning spring on the upper point. The problem is that these points are made with dies in stamping machines and those dies require lubricant to work properly. Apparently the manufacturer is not removing all traces of lubricant. Many times you will find this lubricant under the cushion spring. Try to imagine the surface tension effect of this lubricant on cushion spring operation?
2.) Inspect the space under the cushion spring for any metal filings or flashing from the stamping process. If present carefully remove it so as not to damage the cushion spring.
3.) Check the rivet for being cocked and not allowing the cushion spring to move freely. This can sometimes be corrected by lightly tapping the rivet with a small hammer.
4.) Adjust the rivet to limit the total cushion spring movement to about 10 to 20 thousandths. This requires a special home made tool which is a two part die welded into a pair of vice grip ® jaws which also has a nut added to the adjustment screw that lock the grip distance. These dies have holes in them to clear the contact and can move the rivet back and forth depending upon which way you place the part into them. You have to be careful not to move the rivet too many times or it becomes loose and the part becomes unusable.
5.) Tension the cushion spring. The cushion spring needs to be resting on the rivet head with a small amount (just enough to hold it there) of tension and can be pushed back the distance with a very small amount of pressure. To add tension you can roll a nut driver transversely across the cushion spring at the point where there is a small hole near the two small rivets that mount the cushion spring. Go easily with the nut driver and add a little tension each time. Too much tension and you will render it unsalvageable. You can easily add tension but taking it out is very difficult.
6.) Inspect both parts carefully to make sure the contact is properly spot welded. Sometimes they are missing, cocked or loose. You rarely see a failed spot weld on the upper part, usually only the lower. Sometimes you see cocked contacts on both parts. Sometimes you can correct a cocked contact with a light (very lightly, the contact is hard and brittle and fractures easily) tap of a small hammer on the contact with the part on a anvil.
7.) Inspect the mechanical connection on the lower part between the blade and the foot. Hold each piece in one hand and check for a loose joint. If any movement can be detected place the lower part over a square punch handle on an anvil and carefully brad over the stamping on the top of this joint with a small hammer.
Now, the points are ready to mount, but first the top of the coil must be prepared to accept the points. Check the coil top for indentations around the bolts and shim as required. Make sure the coil winding iron core has not shifted. Use another coil as a sample to check the proper height of the core. Usually a light tap with a small hammer will push them back into the winding to the proper height..
By the way, I did not originally find and develop the solutions to all of these problems. I have learned many of these techniques from others who went before me and the credit, rightfully, is theirs.