COP Ignition Development

I found a small amount of time to measure battery cable voltage drops while cranking. The service manual suggests the drops should be no more than a few tenths of a volt. I found the drops were excessive, with about 1 volt on the positive lead and about 0.5V on the negative. I replaced the cables about 35 years ago, with inexpensive universal fit ones of the correct length. It appears most of the drop is in the cast lead terminal ends. I plan to replace the cables, I am not sure if I will build my own with modern stamped and plated copper terminals, and quality bulk cable. I might used stud terminals, with lugs crimped on cable. It will be easy to tap on start switch and other supply taps, or change out terminals.

I also measured the starter current to range from a high of 250 A, and a low of 138 A. The current increases as cylinders come up on compression, the meter is digital, so results are somewhat uncertain. Digital meters capture over a period of time, so when the current varies, results vary. I wish for a needle gauge.

I have heard good things about min-starters. I found a place in TN, called DB electrical. They sells a universal fit unit for $69 new. I plan to install that, at the same time as the cables.

I also measured the distributor drive backlash to be just under 5 degrees. I used a dial indicator to measure the tangential travel of 0.055". The wheel diameter is 2.6", with a circumference of 3.1416 x 2.6" or 8.168". The angle is estimated as 720 x 0.055/8.168, or 4.8 degrees. I have purchased a new mopar performance intermediate shaft and new drive bushing. I am also making a tool to pull the bushing. I will install the new parts and check the backlash. There is some wear in the original shaft, I am a bit surprised by that.

I also captured the distributor signal and decoder output while cranking using my logic analyzer. I expected to find faults there, but did not. I will report back in a week or two. Most of my time now is spent with spring farm chores. I have more trees to cut, and garden to plant.