72T ignition questions

Having just rebuilt the motor in my '72T, I am having no luck getting a spark from either the coil or the plugs. I checked the voltage from the CD unit to the coil (11 volts+) and that seems to be okay. The resistance across the windings of the coil seem to be within +or- 10%, I'm also assuming that is satisfactory.
Where am I going wrong? Is a faulty ground possibly at fault? Is the coil gone? I know there was a spark before the rebuid, since it ran fine but smoked. Any help would be apreciated; building a fresh motor and getting no spark is no fun.

thanks, Jim

Have you double-checked the wiring of the components located on your engine to the wiring harness and at the 14-pin connector to the fuse/relay/CDI-unit console on the left side of the engine compartment?

Is your CDI-unit whistling, or quiet, when the ignition switch is on? There is supposed to be a 'lightning bolt symbol' on your coil, and checking with a voltmeter and probes is not a part of normal procedures (I would normally check that 'hot' side of the coil with an oscilloscope while the engine is being cranked) ... one side of your coil primary is supposed to be grounded and the other normally gets periodic 350-400 Volt pulses from the CDI-unit! There is a color-coded schematic of a '73 CIS 'T' on this site ... Part 2 has the diagram of the engine's electrics, and I suggest you print it out or take a look!!!

If you have information to add, or more questions ... please post. Good luck!

Jim,

I was interuppted during writing the previous posting, so the logic of asking about the engine harnes wiring may not be clear ... the 11 Volt signal level on one side of the coil sounds suspiciously like what you 'should' see at the disributor lead when the points are open ... closed you should see a 'solid' ground.

And, the coil, assuming 'stock' OEM Bosch 0.221.121.001, should measure approximately 0.65 Ohms on the primary, and 676 Ohms on the secondary side.

Have you checked the point gap or dwell angle of the points in the distributor? The nominal point gap is 0.016". Assuming nothing has changed since the engine was last running doesn't seem too wise, at this point. Depending on their age, a bad distributor car or rotor could cause an apparent disappearing spark, too!

------------------
Warren Hall
1973 911S Targa

[This message has been edited by Early_S_Man (edited 08-10-2000).]

something else that might be worth looking
at.. the black wire coming off your points
could be frayed/broken. what looked like just a scuff in that wire was actually all
strands of wire broken on center of wire with
insulation of wire still intact, runs much
better now.