No spark

[jsz]

I helped my 16 year old son this summer and rebuilt the 78, 1.8 l engine. Reinstalled the engine and have no spark.
A little history on the ignition system, a Pertronix, LS1 was installed, 5 years ago and driven on and off till 2016. Car has sat since then.
So , we have power when the key comes on to the blue/black wire, Pertronix coil is new and makes spark.Wires, cap, rotor are new and tested also. Pertronix, was tested and it works. Engine timing was set during the rebuild and rechecked and with engine at TDC, cams aligned, distributor installed with rotor pointing to number 4 pickup.

At a loss on what is going on here, any thoughts are most appreciated.

Jeff

[18Fiatsandcounting]

Reinstalled the engine and have no spark.

Jeff, can you explain a bit more? The engine doesn't start? If you connect a timing light to any or all of the plug wires, the timing light never fires when you crank the engine? If you remove the spark plugs but leave the spark plug wire connected and the metal body of the part grounded, you don't see (or hear) a spark when you crank the engine? Or ???

-Bryan

[jsz]

Bryan, thank you for the reply. After testing each component, they were installed and the engine cranked. No time during the cranking process was spark evident at a spark plug. We checked for spark various ways, including a timing light, inline spark tester and grounding a spark plug.
We are leaning that the Pertronix is bad even though it tests out. Also tested for a ballast resistor, per Pertronix, had 11.7 volts and the battery was 12.5 volts. Based on that, it said to remove the ballast resistor, however we can not locate one.
We know this is a simple issue. Thinking of removing the ignition components and distributor and build a test platform using a drill to turn the distributor over. Thinking we can boil the ignition down to the simplest components and rule out any of the 39 year old car issues.
Thanks again, Jeff

[18Fiatsandcounting]

I wish I could offer more help, but I'm not that familiar with the Pertronix system. In the original ignition system, if you have 12 volts on one side of the low voltage winding of a (good) coil, and the connection to ground on the other side of that winding is properly interrupted by the points opening, then you'll get a spark on the high voltage winding of the coil due to the collapse of the magnetic field. It's pretty foolproof.

One thing to try: Take the cap and rotor out of the equation by seeing if you get a spark from the wire from the coil to the center connection of the distributor cap. In other words, just pull the coil wire from the distributor end and lay it on the engine somewhere so that the metal connector end is an eight of an inch or so from a metal ground. You'll get 4 times the frequency of sparks as you crank the engine, but that's OK.

Also, your plug wires are all OK? Not shorting to ground due to bad insulation, dirt, etc.? Or dirt/oil/grease on the coil?

-Bryan

[jsz]

The plug wires are brand new and were tested via a ohms meter.
Essentially, everything is new from the coil, with exception of the Pertronix and distributor body.

[spider2081]

I thought I responded to this earlier.
Anyway if I remember correctly a 1978 Spider originally was a dual point car. An ignition control relay was used to select the desired points. This relay is not used with the Pertronix igniter.
The pertronix igniter has a red wire and a black wire. The red wire and the original Light blue/back wire from the ignition switch connect to the coil's + terminal. The igniters black wire connects to the coil's - terminal. I have found the Pertronix systems to be voltage sensitive and they require more than 10 Volts Dc when the engine is cranking to trigger the coil. Have you measures the voltage on the red wire for the igniter when the engine is cranking over? Also if I remember correctly while the engine is cranking over if you measure the voltage on the black wire connected to the - terminal of the coil it will be quite a bit less than the red wire when t he engine is cranking if the igniter is triggering the coil.

I think you have manually tested the coil by grounding the coils - terminal and looking for a spark when the ground is lifted is that correct?
You can check the distributor rotor and cap with the same procedure by knowing which spark plug the rotor is pointing toward.

[18Fiatsandcounting]

... if I remember correctly a 1978 Spider originally was a dual point car.

Correct, 1978 was a dual point setup. I owned a '78 for many years, and the dual points drove me crazy until I figured out how they worked.

-Bryan

[jsz]

Tested the voltage of the blue/black wire to the + side of the coil, ignition switch on, 12.03v and 10.07v during cranking. So we replaced the Pertronix, LS1, which tested ok with a new one, one crank and it fired right up. Let it come up to temperature and then timed it. Seems running very well after engine rebuild. Went to shut off and turned the key to off, engine stayed running. So have to take that apart and repair.
Anyhow it's running well, we appreciate the help.