Spark plug proper resistance question.

[76eldo]

My 70 Eldorado needs a tune up. Not running and idling as smooth as it should.
I know how to set the timing and dwell so that will get checked out. New AC plugs will be installed and I have NOS Delco points. Also have an NOS Delco cap.

It's a 15,000 mile car but it's also 50 years old.
I'd like to ask, if you know, how I can test the original wires for a range of resistance. I have an ohm meter amd I am asking what value I should be looking for to see if I need to get new wires.

Thanks

[Daryl Chesterman]

Here is a YouTube video on different methods for testing spark plug wires.

     https://www.youtube.com/watch?v=4_EFGAFxi1w

I hope it helps.  If it were my car, I would just replace them as they are 50 years old.

Daryl Chesterman

[wheikkila]

Good Evening
I would just replace the wires. Like you said they are 50 years old. the rubber is dri rotted. They are inexpensive.
Thanks Wayne 

[76eldo]

For this car I am trying to maintain the original appearance  under the hood. As I mentioned it's a 15,000 mile car. There is no dry rot or splitting on the wires. If they are not bad I don't want to change them. It's not the money.

I think I can answer my own question. I do have a set of NOS Delco wires that I bought for the 71 Eldorado that I sold.
If I take the longest wire from the new set and measure the resistance on it I can then compare it to the old one and see if there is a difference.
I can also run the car at night and look for any arcing.

If they are bad I'll change them but I'm hoping to change the points and plugs only.

[76eldo]

Thanks so much for the video.
It's exactly what I was thinking !

[savemy67]

Hello Brian,

I don't recall that there are any significant differences in the ignition system between 1970 and 1971.  If this is the case, you may want to take the longest of the 1971 NOS wires (since they are unused), and measure the length of the wire in inches.  Measure the Ohm value of that wire.  Take a few readings with your meter and average the readings for that wire.  This will give you an Ohm value per inch for the 1971 wires, which you can use to check the 1970 wires and determine if they are within tolerance.

Respectfully submitted,

Christopher Winter

[bcroe]

Agree here with the video water and resistance check.  I would
not worry about exact ohms per foot, they should all be reasonably
close in value.  Finding a bad wire, I would replace them all. 

My expectation is that the big wires on an HEI will have a
longer, more dependable life, than that small cap, points stuff. 
good luck, Bruce Roe

[79 Eldorado]

I've mentioned this before but I've used a digital tach timing light to identify a single bad wire. Instead of only placing the pick-up, for the timing light, on the nr 1 cyclinder only I measured the RPM of each wire one by one and recorded the RPM on the tach. The one I was having an issue with read half the RPM of any of the others.

Scott