Datsun 521 Matchbox Distributor NO Spark

[Datotrav]

Hi everyone, I have a 1971 Datsun 521 which I bought as a project and I have just finished rewiring most of the car and I am having a no spark situation and was hoping someone might have some insight. I have a L20B with a rebuilt matchbox distributor that was purchased from California Datsun and a brand no matching high energy coil from a 1979 620. I have the wiring set up with two wires going to the + side of the coil (one that has power with the ignition switch in the on position and one when it is in the start position), then the + side of the coil is going to terminal B on the matchbox and the - side is going to terminal c. The distributor has a dedicated ground going to the frame. When the key is in the on position I have 12 volts going to the coil and 12 volts when cranking but still am not getting any spark. I pulled the coil plug wire off the center of the distributor and held in about an 1/8" away from ground and I am not getting any spark. Could my new coil possibly be bad? Any help or advice would be greatly appreciated!

[datzenmike]

Excellent description so that everything is covered and not much to ask for.

 

First thing I would do is put a spark plug in the end of the coil wire and lay on a grounded surface. Turn the key on and touch a ground to the - side of the coil and release. What you should see is a spark.

 

Yes there is a spark.... the coil is good.

No spark...................... the coil is bad

 

 

Next...

Take the cap off and have someone turn the engine over with the starter. Is the rotor turning? I know, seems silly but ....

[Datotrav]

Thanks for the reply Mike. I should have mentioned as well that the I took the cap off and the rotor was turning, I have the distributor static timed and the firing order at 1-3-4-2. I grabbed a spark plug and put it in the end of the coil wire and laid it across a grounded surface and got some weird results..I was able to get it to spark twice out of the 10 plus times I put the - side of the coil to ground and the spark was very weak. Should it have spark every time the coil negative gets touched to ground? I'm super excited to get this project running but can't seem to figure this spark issue out

[INDY510]

the ONLY wire going to the coil ground should be from the distributor:

 

[kelowg]

Sound like bad ign module. gm hei modules r super cheap,but have to be well grounded. being from cali datsun, this doenst suprize me. 

[datzenmike]

http://community.ratsun.net/topic/66882-dont-do-business-with-california-datsun-formely-datsun-parts-llc/

 

Try returning the module for a replacement. The HEI module is another good option.

[Datotrav]

Thanks again everyone for the replies. Indy510 yeah that's how I have mine wired the ground post is going to fresh ground metal on the frame, the positive side of the coil is going to terminal B and the negative is going to terminal C. The previous owner was the one who bought parts from California Datsun and I keep running into some very questionable parts from him. I'm going to swap the coil out and see if that works, is there any way of testing the ignition module on the distributor?

[datzenmike]

TEST THE COIL!!!!!!!!!!! No need to pull thinks out that might be working just fine. There's the chance you may put a bad one in and add to the original problem. In addition you may be installing an inferior part.

 

 

Key ON ground negative side and spark or no spark.

 

 

 

No easy way to test the distributor/module really other than substituting an HEI module. If it works the matchbox is bad. HEI are what $20 new? Free from a wrecking yard.

[Datotrav]

I have tried testing the coil like Datzenmike suggested and I got the coil to spark twice out of the 20 times I touched coil - to ground and it was a very weak spark at that. I just wasn't sure if it is the coil making the intermittent weak spark or the ignition module?

[datzenmike]

The module does the same thing as touching a grounded wire to the coil negative side. If you touched the coil negative terminal to ground then you have eliminated the module. You should get a good fat spark every time. If the coil connections are good and you get intermittent spark try a different coil. Any coil will do just to prove it's the coil you have now that is bad. Then buy the correct new coil.


Do you still have the ballast resister connected? You shouldn't. You should have a full 12 volts from the ignition switch.

[banzai510(hainz)]

why not just hook up the stock coil and see if sparks. Just for testing. then you know the distributor electtronics is good.

 

 

red the olddatsuns.com tech section!!!!!!!!!!!!!!!!! for more info

[Datotrav]

Thanks everyone again, it ended up being a bad coil. The parts place that I purchased the coil from swapped it out for a new one no charge. Its frustrating to buy new parts that are bad though, but with everyones help I got it figured out. Thanks

[DanielC]

This is more common that you think.  Nissan OEM electric parts are very reliable.  I would trust a used alternator, starter, ignition coil, matchbox distributor, on a Datsun, or a Nissan from a junkyard before I would trust a new or rebuilt part from a auto parts store.

 

Go to a junk yard get a coil off some other Nissan.  You can also use a ignition coil that requires a ballast resistor.

If you go with a use a ballast resistor coil, wire it like this:

[datzenmike]

The Nissan ignition module does more than turn the coil on and off, it also has several other features built it.

 

There is a duty control circuit that sets the 'make and break' for one cycle. This is the equivalent of the dwell in points distributors but varies with RPM. Thus at high speed the coil gets more time (dwell) to build the magnetic field than at low speed.

 

There is a preventative circuit that cut's the power to the coil if you turn on the ignition but then do not start for whatever reason. This prevents the coil overheating and isn't a draw on the battery. If there isn't a trigger signal to fire the coil the module will 'stand down' until there is. So you can leave your ignition in the on position without worry to the system.

 

There is a current limiting device to prevent it exceeding a certain level through the coil..