My new [to me] Midget Problems! Coil trouble?

[Seik]

I just bought a 1967 MG Midget in good condition. Body and paint work are great. It arrived off the truck a couple of days ago.

Anyway, I drove it off the truck and then started it a few times since then. However, yesterday it stopped starting on me, and I just have a few questions. Keep in mind, this is my first ever restoration so I'm a relative newbie at this. I apologize if I ask or say anything dumb. /ubbthreads/images/graemlins/tongue.gif

It's not starting. Ok, engine is turning over and starter is working properly. Battery works. There is compression. I disconnected the fuel lines at the carbs (Weber downdraft conversion) and fuel is pumping through steadily. So fuel is getting to engine and fuel pump and carbs working properly.

I am getting no spark to engine. There is no spark in the plugs, also there is no spark coming from either the coil wire, nor is there any spark coming from the coil itself. There are 4 wires connected to the coil (can anyone tell me where they are from/going?). I AM getting spark from one of those wires (possibly the one coming from battery?). I checked the distributor and everything seemed ok. There are new wires and the points seemed good, good rotor and condenser too apparently. Could the coil be the problem?

So, if I am getting no spark from the coil, would a new one solve the problem? And if so, which coil is reccomended to get? The coil in there now looks original, or if not, then very old. Also, what is a ballast resistor and do I need one for my coil? Finally, when I turn my key half way to ignition it makes a clicking sound from the fuel tank area. Is that a normal sound for the pump to make? It seems quite loud.

Thanks and I would appreciate any input. Chances are this will only be my first "dumb" question of many more to come if I keep at this. /ubbthreads/images/graemlins/smile.gif

 

[sparkydave]

Hi Seik, if you have 4 wires going to the coil, those should be one thick wire coming out of the tower that goes to the center of the distributor cap, 1 small wire going to one of the terminals to the side of that thick one, and two going to the other terminal. The thick one in the center is the high voltage lead that goes to the spark plugs by way of the distributor. The smaller ones carry the current on the primary of the coil, and interrupting the current using the breaker points in the distributor creates that high voltage. One of the two wires that share the terminal go to the starter solenoid, and this bypasses the ballast resistor to provide more ignition voltage to the coil when starting. If you have a 12 volt test light (cheap at any auto parts store), you should be able to connect the light across the two primary terminals of the distributor, and the light should light up (albeit dimly) when the key is on. If it doesn't light, then something is wrong with either the ballast resistor, the points, or the wiring to the ballast resistor. Then, if you can get a helper to crank, the light should light up brightly and be flickering. If it's flickering and still not starting, then either the coil is bad, the ignition wires (the fat ones) have a problem, or the rotor is not working right. When you say you got spark from one of the leads, it should have been the fat one, and only while the engine was cranking, and in that case the coil is working. Here's a link to a page that has some useful MG electrical info too https://www.mgcars.org.uk/electrical/. Oh, and the fuel pump clicking is normal.

 

[Seik]

[ QUOTE ]
When you say you got spark from one of the leads, it should have been the fat one, and only while the engine was cranking, and in that case the coil is working.

[/ QUOTE ]

Thanks for all that info. I've got to pick up one of those 12v light testers. I had one once, but never used it, so it's now lost somewhere never to be found. I'll do that test tomorrow.

I quoted you because I'm not getting spark from the fat lead out of the coil. Instead I've found I'm getting spark from one of the smaller wires that plug in around the fat lead from the coil. So does that constitute a coil problem? /ubbthreads/images/graemlins/confused.gif

I should go read the Haynes manual more thouroughly I guess. And read that website you gave me very closely. It seems informative. /ubbthreads/images/graemlins/laugh.gif

 

[dklawson]

If you are seeing a spark jump from one of the small (low-tension) wires to the center (tower) terminal of the coil, it's more likely that you have a problem with your cap/rotor/spark plug wires. However, I suppose you could have a crack in the coil tower.

I'd start by examining the rotor and the carbon button in the dizzy cap. If they're OK, wipe the wires down with WD-40 and try starting the car again. If the WD-40 helped, buy new wires.

I put together a troubleshooting PDF for my Mini owning friends. Your '67 will be similar. You can get my PDF at:
https://home.mindspring.com/~purlawson/files/LucasPointsIgnitions.pdf
Perhaps it will help.

 

[ThomP]

Could it be that the points just closed up?? I would suspect everything BUT the coil to start.

 

[spritenut]

I just read where 99 out of 100 replaced coils never needed replacing.
Check the points first. Remove the dizzy cap, turn on the key and manually open and closr the points with a screwdriver.
If you see a spark, all is good.
And to test the coil, spark the points again this time with another screwdriver from inside the coil to the fat wire, Make sure there is a 1/8" gap between the screwdriver inside the tower and the evd of the coil wire.
When the points spark, there should be a spark from the coil.
The spark comes from the points, the coil is just a transfomer to up the voltage.
If you do get a coil spark, suspect a bad rotor which is not delivering that spark to the plugs.

 

[Seik]

Thanks for the help guys. The links especially helped.

Turned out it was the points. I set them and adjusted the timing and it's running pretty good now. There's massive hesitation when I floor the gas pedal though, so something is out of whack in the carbuerator. I also hear air leaks in the engine so I think a seal or gasket is messed up and some of the exhaust is escaping.

But hey, now it's running.

 

[nathandarby67]

Keep in mind 90% of carburetor problems are located in the ignition. Or as Butch Bohunk once said, "don't go screwin' with the darn carburetion until you're sure yer *&%@#$ sparks are in order!"

I would read your Haynes manual and use a dynamic timing light and make sure the spark advances as it should across all rpm ranges. That could very likely be the "bogging" you are feeling when you give it the gas....perhaps the advance mechanism is not working as it should. It is one thing to set the static timing and get it to idle, and another to get the dynamic timing straight. Also make sure your plugs are gapped correctly. If the car looks like it hasn't seen any new parts in awhile, I would replace the points, condensor, rotor, cap, wires, and plugs BEFORE I started really mucking around with the carbs, just as a matter of principle. Then once you get the timing set you will KNOW that any problems are from fuel delivery, and not be wasting time chasing ghost carb problems that aren't really there. You will also potentially avoid covering up one maladjustment by adjusting something else out of spec. It is amazing how many layers of wrong adjustments can be covered up by other "adjustments". Since this car is new to you and you don't really know what all has been done to it, I would strongly suggest starting back at square one, and square one when tuning ANY engine is ALWAYS a properly functioning and timed ignition system! And when you do get ready to adjust your carbs, keep in mind it is impossible to correctly set carbs if the ignition is not working properly, so you will only be wasting your time. Anyhow, best of luck to you. You will have a blast AND learn a ton working on your car! You have already found one of your best resources right here on this board!

Nathan