Inliners International Forums General Discussion Engines No spark

I am new to this site, so attempting a post. I inherited a 56 GMC truck that I am trying to start, after 9 years in storage. I found out that the original engine has been replaced with a 58 vintage 235 motor. I have cleaned out the fuel tank and lines, rebuilt the carb, but no spark. I thought it may be the coil, so tried a couple of borrowed coils, but no luck. I have 12 volts at the distributor positive and negative connections. Also replaced the condenser in the distributor. The cap, rotor and points all look new. Any suggestions on what to look for. The circuit looks so simple, what else can go wrong?

Is the distributor shaft turning ?

You should have 2 wires on the + or ign side of the coil; one from the ignition switch via the ballast resistor and one from the starter. That connection will read +12 volts with points open and around six volts with the points closed when not cranking on the starter, 12 volts at all times when starter is engaged (-2 or 3 volts from starter drag). The - or dis side side of the coil should be wired to the distributor and should read around 12 volts with points open and zero volts with points closed. That is the complete low tension circuit. If you don't get zero volts on the dis side of the coil with the points closed you will get no spark.

I recently started a '65 Rambler that sat in a barn for 7 years. When, just like you, I tried to start the engine I found no spark at the plugs. The points also looked new, but under closer inspection, I found that there was a fine film of gray on them. I carefully filed them to a shiny, smooth finish and the engine fired like it had just been sut off yesterday! Even though the points LOOK OK, they may not be making a good electrical contact. If the rotor is turning and you have current to the coil, and out of the coil, then the only reason for the engine not to fire, is the condenser, or the points.

A good, quick, way to check if the points are making contact, or not, is to connect a test light to the Negative terminal of the coil and to ground. When you turn the engine over, the light will come on when the points are OPEN, When the points close, IF THEY ARE MAKING A GOOD CONTACT, the light will go out. If the light stays on, you know your points need attention.

Thank you for the advice, I will try these things and let you know how I make out.

Hi Dennis

You were so right about the points. They looked fine, but had a coating on them. Even when I filed them down, they did not work. Once I replaced them, the test lamp worked as you said, and I was able to fire up the engine, after sitting for 9 years