Thursday, September 15, 2011

Antique Ford V8 Ignition Coils with Non-Metallic Cases

If you have a Flathead Ford V-8 1932-1948

Does it have trouble:
Ø  climbing hills?
Ø  going fast?
Ø  cranking after a short trip?

Then you probably have too much water in your ignition coil.

We can help!


Revitalization for Flathead Ford Coils through Moisture Removal ~ A process engineered & offered by John Shelor.

If you think that six drops of water in an antique Ford engine coil is not that detrimental to the voltage output . . . THINK again! Six drops of contained moisture lowers the average voltage output by 3,263 volts! The average Flathead coil has about 20 drops of moisture!

If the voltage output of your coil drops below 15,000, it’s likely that your car won’t run well up a steep grade or crank after you’ve stopped for a short period of time.

John’s vacuum process removes the moisture resulting in an average increase in output voltage of 11,000 volts. That’s a 68% improvement per coil on average. We test each coil before and after. John has been able to improve the performance of 90% of the coils he receives.

How it Works:

1.   We place your coil in a vacuum chamber.
2.   A high vacuum is pulled on the chamber.
3.   Then the chamber is flooded with dry nitrogen.
4.   This is followed by another cycle of high vacuum.
5.   The system continues to cycle between vacuum and nitrogen for approximately 175 cycles over a two-week period.
6.   We periodically collect the water from the vacuum sump. It typically results in 20 drops total per coil.





Parts of this article by John Shelor first appeared in the V8 Times, Volume 42, Number 3 and Number 4. John is a Mechanical Engineer and Journeymen Electrician with a passion for improving old Ford engines.


The Problem with Antique Ford V-8 Ignition Coils

Everyone who has early Ford V-8s knows that the coils with non-metallic cases can be a problem. But to my knowledge, no one has defined the problem.



The problem with antique Ford V8 ignition coils is absorbed moisture 

The coils have been subjected to thousands of reversals of barometric pressure, water vapor always present in the air, and coil cases not designed with effective moisture seals. Water has been breathed in and has set up residence.

The electrical resistance to ground has been reduced and the designed output voltage can no longer be achieved. There is rapid voltage loss of an impaired coil as the temperature increases.

During 2002, I developed a process to remove moisture from the inside of early Ford Motor Company ignition coils that were built with non-metallic cases. The cases were inadequately sealed to resist moisture.

Removal of the moisture allowed an increase in output voltage and added to the value and usefulness of the coil.

The following information was published in the May/June 2005 issue of the V-8 Times. It contains an explanation of how and why the process works, and describes some results.

"There is a magical coil processing machine in my basement that can reverse the detrimental effect moisture has had on ignition coils. The process uses heat, pressure variations, and dilution to remove moisture from inside the coil cases and restore the lost coil output voltage. Detailed information about the process will be presented further on.

I am willing to rest my entire case for absorbed moisture being the major cause of substandard coil voltage output on the recent treatment and testing of ten 1937-1941 ignition coils.

The following chart shows increased voltage of 10 ignition coils after a single, 50-cycle removal treatment.

                 Previous          Latest          "Stressed"         %
Coil          "Stressed"       "Stressed"      Voltage        Voltage
Number      Voltage          Voltage         Gained         Gained
 315            13,500           21,000          7,500             56
 271              7,000           10,500          3,500             50
 319            10,000           14,500          4,500             45
 300            16,000           22,000          6,000             37
 276              9,500           13.000          3,500             37
 270            16,500           22,500          6,000             36
 267            17,500           23,000          5,500             31
 321            14,500           19,000          4,500             31
 265            17,500           21,500          4,000             23
 275              3,000             3,000                 0               0   
Average       12,500           17,000          4,500             36%        

The following chart shows 6 of the same coils that went through multiple campaigns of moisture removal treatments.

                    First               Latest       "Stressed"         % 
Coil          "Stressed"       "Stressed"      Voltage        Voltage
Number      Voltage          Voltage         Gained         Gained
 315              5,500
 319            10,000           14,500          4,500             45
 300            16,000           22,000          6,000             37
 276              9,500           13.000          3,500             37
 270            16,500           22,500          6,000             36
 267            17,500           23,000          5,500             31  
Average       12,500           17,000          4,500             36%   


The Ignition Coil Stress Test 

"Stressed" voltage defined - "Stress" voltage is the output voltage a coil with hot windings will produce on a test designed to simulate the prolonged use of a coil on the highway.

Evaluating the output voltage of ignition coils with a bench test is a convenient way to predict how the coil will perform in actual use.

The following Stress Test Procedure was used for several years:
A. Check the primary and secondary windings for continuity. If either circuit is open, the coil is a reject.
B. Perform an ambient temperature voltage output test (Special meter required). Good coils will usually produce 28,000 to 30,000 volts.
C. Heat the windings with a current flow for a standardized test (27 minutes @ 4 amps).
D. Rerun the voltage output test and expect less than the voltage achieved on the ambient test.
E. Classify the coils according to "Stressed" voltage as follows:
  •            26,000 v. and up - Superior
  •            22,000 to 25,500 v. - Very good
  •            18,000 to 21,500 v. - Good
  •            14,000 to 17,500 v. - Marginal
  •            Below 14,000 v. - Poor
One very important aspect of tests or evaluation is the necessity for a standardized process or procedure. To that end, the coils are serial numbered. The same condenser is always used the distributor used as a triggering device is always rotated C.C.W. @ 1500 engine R.P.M. with 4.2 volts supplied to the coil, and always with the positive side grounded. The output voltage is measured by a voltmeter specifically designed to read spark output.

We are now ready to walk through a heated coil Stress Test.

The coil is heated by passing 4 amps DC through the primary winding for 27 minutes. The heated coil is quickly moved to a distributor machine for a spark output test as described above. The test results are logged on to a special form. Two different forms are used: one for first time tests, the second for all subsequent trips.


The Moisture Removal Process Cycle Step by Step

  1. Load about 20 coils into an ordinary pressure cooker supported on a stand.
  2. Evacuate the space in the pot to about 27-inches of mercury with a vacuum pump.
  3. Refill the evacuated space to atmospheric pressure with dry nitrogen gas.
  4. Apply heat to the pot with a heat lamp on the top and on the bottom. Continue the heat for the duration of the daily run.
  5. Pump the pot down again to 27-inches of vacuum after 2 hours heat time.
  6. After another two hours, fill the pot to atmospheric pressure with dry nitrogen.
  7. Alternate the pressure between 27-inches and atmospheric each two hours and try to accomplish five complete cycles per day.
  8. Shut down at night by pulling and maintaining a 27-inch vacuum and turning off the heat lamps.
  9. Repeat steps 3 through 8 for 8-10 days (40 to 50) complete cycles.

An Explanation of How and Why the the Moisture Removal Process Works
(Refer to the steps above)

2. 27-inches of vacuum (3-inch mercury absolute pressure) removes about 90% of the gases, including water vapor, contained in the vessel. 27-inches of vacuum also reduces the boiling point of water to about 115 degrees F.

3. The nitrogen fill adds virtually no moisture to the space, but does contribute to the heat transfer by providing a medium for convection within the pot.

4. The aluminum pot reaches a temperature in the 130-135 degree range.

5. Each time the pot is evacuated, two things are accomplished. The coils are forcefully encouraged to breathe, and 90% of the water vapor that has accumulated in the contained space is extracted.

The ambient temperature voltage output test sets the limit for coil output. All other tests will show less output. Low ambient coils can sometimes be recovered with an extraordinary amount.of work. But the success rate is low.

Originally, I classified coils as good if the "stressed" voltage was 13,000 and up. Recently I have increased the value to 18,000 to be ultra conservative. The manufacturer of the spark output meter suggests 15,000 volts as the reliable minimum. I am presently using a coil rated 14,000 volts on my 1940 pickup and it runs flawlessly. I would also like to point out that I have run coils rated 16,000 and 18,000 volts for 30, 60, and 90 minutes on hot summer days with no difficulties.

The hot "Stressed" coil test has proven to be valuable in sorting good coils from bad coils so that  the old flatheads can hit the road with confidence. It is simple, direct, and accurate. Coil output voltage recovery offers an alternative to popping the rivets and replacing the primary and secondary windings.

When people learn that over 80% of coils with continuity in both windings can be recovered they may not be so quick to toll them out. People with an ample supply of  original coils might want to store them in such a way as to maintain or improve them as we move forward 50 to 100 years.

Possibly store them in sealed plastic bags containing a desiccant such as unslacked lime or silica gem.

I stand by my findings as stated above.

Test include:
  • Coils "Stress" tested - over 350 (editor's note - this number is now much higher since this article first appeared in 2005)
  • Coils subjected to the moisture removal process - over 168.
  • Lincoln V-12 coils recovered 1/1 - with a voltage gain of 68%
I have tossed in additional information pertaining to Ford ignition not necessarily related to coils or coil testing.

Ford Ignition Coils - 10 Things I have Learned About Flathead Coils
  1. If you are not hot testing coils, you are not testing coils.
  2. A functioning condenser triples the output voltage of the coil.
  3. Most good coils of the flathead era can produce 30,000 volts.
  4. Broken ears and cracked cases do not necessarily reduce output.
  5. Always be sure that the tip of the contact spring is clean and bright.
  6. Open circuits in the windings are not the most prevalent problem.
  7. Output voltage of inferior coils drops off rapidly when the coil is hot.
  8. 1932 coils are very scarce but generally perform well.
  9. 1942-1948 coils seem to be deteriorated faster than others.
  10. N.O.S. means that is has had 60 or more years to absorb moisture.
See the article Ignition Coil Moisture Revisited to learn about the updated process currently in use.






1 comment:

  1. Excellently amazing and exciting too. Can you please mention me the source of your reference... I am happy that at least somebody gave this subject an attention.

    ReplyDelete