double sparking coil

[Ed Saniewski]

I got a Strobo-Spark tester and found that my coils are double sparking. I watched the two short videos from fun projects, but they don't tell me how to adjust the coil. I have searched the old posts but did not seem to find a clear easy explanation on how to fix the problem. Any one got a link or video on this, I would greatly appreciate it, thanks.

[Jack Innes]

To eliminate the double sparking the cushion spring tension needs to be corrected by bending the upper vibrator point near where the cushion spring rivet is.

This is outlined, I believe, in the service manual.

[Farmallcub49]

Usually a light tap on the upper point with the proper point hammer eliminates that issue.

[Steve Jelf]

See pages 43-46 in the MTFCA Electrical System book and pages 239-240 in the Ford shop manual.

[Royce P]

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.

[Ed Saniewski]

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Thanks for all the great info. I was able to get 2 of the coils to fire off correctly. The third one the iron core is sticking up too high and is contacting the upper points. I will disassemble it this weekend and tap it down as Royce posted. The fourth coil I can not get to stop double sparking. I have tried tapping with a hammer as in the Ford instructions but no change. I have a few sets of new points, and will try changing them out. These coils were new from Snyders, and I figured I could just drop them in the car and go. Thanks again.

[Farmallcub49]

If they were new from Snyders send them back and ask for your money back. I have rebuilt ones on the shelf ready to go. Drop me a note and we'll go from there.
[email protected]

[CharlieB]

I don't know if this will help because I have a guy that does my HCCing for me and I just watch but I've seen him on occasion clip the round ends off old point sets to make 2 "washers" which he installs under the spacers that the top portion of the points mount on. Seems that they sometimes sink into the wood from over tightening and are short because of it. It looks like a last ditch effort but it seems to work when little else does.

[Royce P]

Andy is dead on. I bought four of those and immediately on installation my T ran terrible. Testing them on a hand cranked coil tester revealed weak double sparking. I talked to a certain coil man who lives in Kentucky who advised I check the capacitors.

Long story short, I replaced the capacitors with the proper sized ones, and set the coils on a HCCT, and they were still weak. I should have sent them back. Expensive lesson learned.

Originally Posted by Farmallcub49

If they were new from Snyders send them back and ask for your money back. I have rebuilt ones on the shelf ready to go. Drop me a note and we'll go from there.
[email protected]