Datsun Roadster Forum-311s.org

I've developed an issue that has left me stranded briefly, which I believe is ignition related. The symptoms are that when the car sits idling for 10 to 20 minutes in traffic, all of a sudden it starts running rough just before it quits. When I try to start the car again it pops but quickly dies again. After no more than 5 minutes the car starts and runs fine (getting me home both times without further incident). While looking under the hood after one such incident, I noticed the coil was quite hot to the touch (140 degrees measured with my scanner). I'm wondering if I have a bad or incompatible coil, or if there is something else that's causing the coil to heat up and then fail. Waiting 5 minutes may be enough time to cool the coil to the point of starting again. Can anybody shed light on this issue?

Vapor lock?
Otherwise you can test the coil with a multimeter.
Linda

I gather this problem has appeared out of the blue, you haven't changed anything that brought this issue on?

Is there any oily residue on the bottom side of the coil?

Is this a points ignition or EI?
Check your ballast resistor - if points. If it is allowing an over voltage condition, driving the coil at 12V instead of 8V, that would burn out the coil relatively quickly. Run the car in the dark and see if there are any cracks causing arc's.

This problem just started, with no mechanical changes on my part. The car runs a Pertronix ignition without a ballast. Good idea to run the car in the dark and look for arching. I'll try this tonight. Does the 140 degree temperature of the coil itself provide any clues regarding what may be happening inside the windings? I verified this morning that there is no oily residue on the coil. Remember, the other clue is that the car starts running kind of rough before it stalls out. Almost sounds like a miss.

Sounds more like vapor lock, than an overheating coil. 140 degrees is hotter than I would like, but I don't think it too hot.
Could also be the Pertronix unit stating to fail. Coil is a cheap fix. Maybe crack the fuel line at the carb to see if you are getting fuel.

A sticking fuel valve, or a bad float have given me those symptoms too, though you would likely smell gas from the overflow. But a tiny hole can be deceptive in the brass floats. I have foam floats now.
Hope your lines are wrapped in Scotsdale.

Linda

The roadster style coil is an oil cooled unit. It is filled with oil. Typically the recommendation is to mount them vertically so that they will never leak the oil. This one may have leaked out the oil and is overheating as a result. That is why I asked about the oily residue.

Just got off the phone with Pertronix and they asked two questions. Is the coil mounted vertically or horizontally (to your point spl310)? Are your terminals at 6 and 12 or 3 and 9? On my car the coil is mounted horizontally and the terminals were at 6 and 12. He claims they need to be at 3 and 9 or you're likely to get an air bubble inside preventing the coil from cooling properly. I've made the change and will report if this solves the problem. Anybody else ever hear that the terminals need to be properly oriented???

The orientation of the terminals is a new one to me. I do question the horizontal versus vertical positioning, as OEM has them mounted Horizontal and I have seen them mounted in every possible direction with other manufacturers - upside down, slanted, horizontal and vertical.

There is one MSD coil that can be mounted anyway needed, the high vibration one.
Otherwise,I believe an MSD coil is not exactly correct for a Pertronix unit.
I see that MSD recommends the ballast resistor for points.

Linda

It could be either slow fuel or a bad coil. I have experienced both. They will both recover temporarily after sitting for a few minutes. I Have never experienced a coil getting anywhere near 140 when still good. To determine whether it is fuel or gas remove a plug and secure it where it will ground and check the spark. Take your spark plug wrench and whatever you used to secure it with you when you go for a drive. When it dies immediately stop and remove a plug and check for spark. Then you will know which it is.

What engine ?
1600
fuel boiling in the bowl a possibility exhaust close by
Only does it idling for 15 min?
K D. Makes a spark testor. adjustable to see coil output
It's a great trouble shooting tool