Ignition Wire Issue - Need Help

[bobswei]

On my 70 911, I just replace the ignition wires, trying to get rid of, what felt like a miss. I put the brand new wires on and it just popped and backfired and wont start. I checked and rechecked the firing order with no luck. All looks correct. I put the old original wires back on and it starts right up. I was able to replaced the new wires with some "newer" wires, installed them and the same popping and back firing. Here is a photo of my original wires. Notice one of the plug connectors is black, which I believe is the newer style but the wires are the same. The new sets are the black connectors. I'm wondering if the black connector was my original "miss" and all the "new" wires are not compatible with my ignition system. I'm stumped.
Does anyone have any idea what's going on here? Cause I don't.
Thanks for any input,
Bob

[pete3799]

Test them with an ohm meter.

[bobswei]

Thanks Pete, I just tested them. I had my meter set to what I think is ohms, the upside down horse shoe. The old set of wires mesured from 2.3 to 2.6 and the new set of wires measures 1.1. So, there is a difference. New wires have less resistance? Does this mean, I have the wrong wires?
Thanks....

[ossiblue]

Are you measuring the resistance of just the wires, or the wires and the connectors?

I ask because the connectors you show look to be Beru and they should have a resistance of around 3K ohms as they have internal resistors. Wires alone should have very little resistance and the connectors for the distributor should be about 1K ohm.

If you measurements were of just the wires, you need to check the connectors as they are notorious for losing continuity of the internal resistors, especially when warm, running and vibrating. Broken resistors in the plug connectors can cause plenty of misfire havoc.

[bobswei]

I was measuring the wires with the connectors. And yes, they are the Beru wires as are the new ones too. So, since they have a total of 1.1 ohm (new wires), maybe this is just the connector at the distributor? And the plug connectors have no internal resistors? Another thing I just checked, the old coil wire measures 7.1 ohms and the new coil wire measures 0.0. I thought, the lower the resistance the better? I'm completely lost on this one.
Thanks for any suggestions,
Bob

[bobswei]

Just a thought: Could I possiable have a coil problem? Maybe spark plugs? Points? The Dist cap and rotor are brand new (just in case those were in question).
Any ideas? Anyone?
Thanks......

[5495bb]

I'd check for arcing at the distributor end. My experience is the lower the resistance the better. Incorrect resistance (within a reasonable range) may cause performance problems but it shouldn't shut you down comletely. The backfiring tells you that a plug is firing at the wrong time ie. it's getting power at the distributor and delivering it to the spark plug but at the wrorg time. I'm sure you've doubled checked your firing sequence but try to crank it over in the dark to check for arcing at the dist.

[bobswei]

Thanks 5495bb,
At the moment, Im not able to keep it running long enough to run to the back to check for arcing. I did check my grounds (which I knew were fine) and swap the coil with my 72's which I know is good. Same result. It's now getting difficult to start with the old wires on which I thought one was bad due to a miss. I’ll work on the “cranking in the dark” next.
Thanks