Problem with 24 volt coils

bubagun · Post by **bubagun** » Sun Jun 15, 2008 5:22 am

Assuming all the tubing and plumbing for the distributer venting/ water scavenging system system is properly installed. And a USA made NOS/OEM 24 volt coil is used (I know how scum the foreign made coils are) What would make the coils fry after about 40 minutes of running. The dist is not hot enough that you cannot put and hold your hand on it when the spark gets weak and the coil pretty much melts. A check at the dist connection from the ign switch (engine not running) has shown only 25.2 volts. The truck is on it's 4-5 coil. It is getting VERY expensive at a $100.00 a pop for nos coils. I have never heard of such a thing. It is so simple.....WTF? The RF filter has been removed from the under the dist connection.

Any help or knowing suggestions, would be appreciated.

Post by **wesk** » Sun Jun 15, 2008 11:04 am

If the vent system is cooling the coil, there are no corroded or loose terminals causing high resistance, you for sure have a 24 volt and not 12 volt coil (they come in both voltages for that distributor) and your volts at the distributor are 25.2 not running then that only leaves a high charging voltage when running at 2500 RPM and higher. Check your voltage output from the regulator at 2500 to 300 RPM. It should be any higher than 28.5.

bubagun · Post by **bubagun** » Sun Jun 15, 2008 2:40 pm

Today we ran a separate wire from the + post of a battery (2, 12 volt bats in series for 24 volts) through a toggle switch and then, to the dist.

Started truck up...and then turned the regular ign switch on.(THAT was a mistake) It ran for 14 minutes before the engine quit and BURNING up our "Electrical system by-pass"wire. Really smoked the wire...like running it right to ground. I figure the chink coil's internal windings "touched" the inside of the case and made a short. Wish we had tried THAT w/o turning the ign switch (in the dashboard) on. Very odd. I have never seen anything like THIS before.

bubagun · Post by **bubagun** » Tue Aug 12, 2008 6:45 am

The Generator was dynamicaly tested and found to generate a peak of 30.1 volts. The electronic voltage regulator was replaced. The voltage at the distributor is now 24.5 volts with the engine running. The owner put a hundred miles on it Sunday. Problem is apparently solved. NEVER buy those import coils.

Post by **wesk** » Tue Aug 12, 2008 10:29 am

Glad you got things sorted out.

US made coils will fail if overheated severely. The usual causes are:
1-No ventilation in the hot weather.
3-Shorted primary leads under cap.
4-High voltage. (in excess of 28.5)

24.5 is actually a little too low to keep the battery charged on short runs.
The correct operating volts at about 2000 RPM should be between 28.45 at 40 degrees F and 27.95 at 120 degrees F.