Hey Guys,

Really stumped here. My 1966 f100 352 will not produce any spark. Went ahead and replaced points, rotor, condenser and cap. Also replaced ignition coil and no spark at all. Only thing between coil and ignition is small white rectangular box coming off ignition. Have no clue if this white box is causing my truck to not get spark. Any help would be appreciated.

Rob

 

Do you have power going to the + side of coil with key on? Did you verify the dist is turning?

 

That white box is a resistor to drop the coil input voltage to 8 volts. Check for power at the resistor.

 

I connected the positive lead of multimeter to plus side of coil and grounded the negative lead of multimeter. I got .5 volt reading before turning key and a little over 12 volts after turning key to the on position.
Yes the rotor is turning when trying to start engine.

 

This resistor you’re talking about is 1/2" x1/2”x3” approximately?

I checked for power at the resistor where wire from ignition is connected and got 12.5 volts when ignition is in the on position. I checked for power on side of resistor that was going out to coil and it has same 12.5v reading when ignition is in the on position.

 

If your points are open, that would be normal. Test light on pos coil post will show constant light. Move to neg side and crank, light will flash verifying points are working properly.

 

Brand new points but will try anything at this point.

 

I also could not get spark from plug wire coming off the coil. Earlier I inserted a heavy gauge wire in place of the plug wire of coil so I could reach metal part of truck. Held this wire about 1/8" above metal and had friend crank it and no spark at all.

 

Test light on pos coil post checked out.
When I moved it to neg. side the truck would not crank. This seems to get worse with each passing minute. Checked batt and put it on charger anyway even though it is at 79%.
I'm really confused why my truck will no longer turn over now.

 

Wiggled wires to resistor and made sure ignition wires were on ignition firmly. Truck now turns over.

 

If you have been cranking on it a lot the starter may be getting hot. It than will pull a lot more current and the engine won't turn over even with a full battery. Only crank it for a few seconds than let it cool for several minutes or it will smoke the starter motor. The only two things that come to mind as for spark is a bad coil or the ignition wire where it goes into the dizzy is going to ground. Did the test light blink when ya hooked it to the (-) negative side of the coil and cranked the engine? Has it ran since ya put the new points in? Was it running before ya replaced the points or did ya do that to see if that was the problem?

 

Moved it to the neg. side and stayed light with no flashing. I can't believe the new points are already bad. Could the ignition or resistor be my problem?

 

The only two things that come to mind as for spark is a bad coil or the ignition wire where it goes into the dizzy is going to ground.
Brand new coil.

Did the test light blink when ya hooked it to the (-) negative side of the coil and cranked the engine?
No, the light stayed on without any blinks.

Has it ran since ya put the new points in?
No

Was it running before ya replaced the points or did ya do that to see if that was the problem?
I changed it because it would not start.

 

For $5 I'm thinking about switching out the ignition tomorrow to rule that out as a problem.

 

Your points are not opening. Either they need adjusted or the lobe is already worn off the point set where it rides on the cam lobe. Did ya grease the cam lobe when ya put in the points? Set the points at 17 thousands. I use a match book cover.