411 no spark

[izzo]

Freaky510 and I were playing around with his 411 and got the new slave cyl in

 

afterwards we tossed a battery in and tried to fire it up. No spark. There is power at the coil, but no spark on coil wire or any of the spark plug wires. We pulled the cap off and found a wire that got bare. Replaced the distributor, same problem. Replaced the coil, same problem. Put a timing light on all the wires just to double check and nothing, tested same timing light on another rig and it works fine so we verified the timing light was functional.

 

Any ideas? He said there is continuity on the ground wire going from the negative on the coil to the distributor, on both sides of the wire.

[ggzilla]

A contact point ignition system is very simple.

 

* Make sure you have 12V to the Ballast Resistor (key ON). And a reading or 9 to 12V at the coil + terminal.

* Pull the coil wire out of the cap, lay the wire end on the valve cover

* Key OFF. take the cap off, and rotate the engine untill the distributor cam is opening the points

* Key ON. Use a screwdriver to bridge the points. When you take the screwdriver out, a spark should occur

 

If it doesn't, replace the condensor (which comes with a new points set), or use an old condensor for testing.

 

If it does spark, then likely the wire is pinched/grounded OR the points are bad. Try sanding them with a fingernail emery board, then set the gap anew.

[ggzilla]

Oh, you can test the wiring like this.. When the engine rotated to where distributor is on the cam (points open), the coil+ voltage should rise to 12V. then when you bridge the points, it should drop to 9V or so. If there is no change (or no voltage) it is a wiring problem.

 

Coils rarely go bad, so that's the last thing I would suspect. You can test the coil with an ohmmeter.

[izzo]

Thanks GG!

 

Brian took it all apart, put it back together and it fired right up. Mystery!

[ggzilla]

good news!

 

Driving a Datsun along the coast highway was my highlight last year.

[izzo]

I do it daily :lol:

 

But, actually driving it down the coast a ways is a blast. Such great scenery, enjoyable cruise. Someone always asks what you're driving too

[dimeguy]

Maybe I am having the same problem? '70 510 2 door. Ive never had any issue starting, even after the car sat for months(aside from a quick shot of starter fluid in the carb). I did nothing to the car other than inspect the park plugs and look under the valve cover. Coil and resistor(white cube shape above?) get warm, but I get no spark spark at the cable end connecting to the distributor. Same symptoms, could it be the same problem?