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French Super Cub Firing Problem

Sat Jan 05, 2013 1:11 pm

Andy here from the UK. My 1958 Super Cub recently purchased in France was converted some time ago from 6 volt to 12 volt (no magneto).

I have changed the points, plugs and checked everything through - but no spark at the plugs or the points. The Ducellier coil looks faulty and I have swapped with a new standard UK made 12volt coil. I have not changed the condenser.

I have referred to the manuals for US and French built tractors of that year.

Some questions I could sure do some help with:
1 Is the type of coil critical?
2 Are there 6v and 12v points and condenser - or will one type of each do the job?
3 One third spare wire from the back end of the generator is not connected - not sure to what that connects - could that be critical?
4 I have changed the engine oil and filter. Also primed the pump as previously advised. Should oil pressure register when the engine is cranked or only after she is running?

Any help greatly appreciated.

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 3:08 pm

Let me answer your 4th question first. No I would not expect to see oil pressure while cranking.
I find it tough to shoot a trouble when people just start changing this and that before asking for help., I never know if they have introduced more trouble.
That said is the key on or the kill switch in the run position? If so do you have 12 volts to there? If so do you have 12 volt at the distributor? If so do you have 12 volt at the 12 volt side of the coil?
I have to assume you have a volt meter and know how to use it. When I don't have one checking this part of the wiring I connect a piece of wire under a ground screw and look for a spark as I brush it against the non ground battery terminal first to see what a good spark looks like and then I bush it against the points at which I want to test looking for an equally good spark. Don't hold the wire on for long just brush it against the point you are testing. One thing he points should be closed when you test at the coil.
6 volt 12 volt will not affect the points and has little affect as respect to running or not for the condenser.

Try this much and let us know the results of your testing.

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 3:19 pm

AndyMac wrote:Is the type of coil critical?
You need a resistor in front of the coil to drop the voltage at the points. I usually use one made for Chrysler products. You may find a similar resistor for British or European vehicles. The other alternative is to use a coil with an internal resistor.
Are there 6v and 12v points and condenser - or will one type of each do the job?
Same.
One third spare wire from the back end of the generator is not connected - not sure to what that connects - could that be critical?
Not likely for starting and running the engine. Check the wiring diagram for your tractor.
Should oil pressure register when the engine is cranked or only after she is running?
Only after engine is running for a few seconds.

To echo Beaconlight. You will need a multimeter or test light to determine the source/location for the lack of voltage to the distributor. Basically, ignition on. Start checking for battery voltage at the points, following the ignition circuitry, work back until you locate battery voltage. The problem will be the wire or appliance previously checked with no voltage.

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 7:26 pm

a bad condenser will ground out the fire ,

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 7:50 pm

AndyMac wrote:I have changed the points, plugs and checked everything through - but no spark at the plugs or the points.
Have you had the tractor running?

Common mistake during the changing of points and condenser is to get the points and condenser leads on the wrong side of the insulator. Thus grounding/shorting out the ignition system.

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 8:03 pm

one thought came to mind when you mentioned a loose wire at the voltage regulator. On 1955 and newer battery ignitions the power to the ignition came throught the voltage regulator. that might be the wire you said was not connected. If memory serves me right the ignition would get power from the L / load terminal on the regulator. I dont know if the French cubs were wired the same for shure but I dont see why they wouldnt be.my 1957 cub loboy gets ignition power from the L terminal on the regualtor.

Re: French Super Cub Firing Problem

Sat Jan 05, 2013 8:20 pm

If it is an original French cub it has a different electrical system

Re: French Super Cub Firing Problem

Sun Jan 06, 2013 6:53 am

Many thanks for all the suggestions. We do have a proper volt meter so will try everything as suggested. The tractor was purchased in knowledge of a fault with the ignition and we have not had her started - so we are feeling our way. She is otherwise in very good condition. Will let you know in due course if it comes up roses (or otherwise).

Re: French Super Cub Firing Problem

Sun Jan 06, 2013 4:10 pm

One thought that I know you have a volt meter and know how to use it. You may read a voltage at no load but not get enough current flow when the circuit is on due to corroded connection and or terminals. This happens most often with lights for they use more current than the ignition does.

Re: French Super Cub Firing Problem

Sun Jan 06, 2013 10:16 pm

To see if you've got enough current flow, watch the volt meter while cranking. It should stay above 10 Volts, preferably above 11 Volts.

Re: French Super Cub Firing Problem

Sun Feb 17, 2013 5:55 am

Just an up-date to let you know Super Cub has fired into life and runs like a Swiss watch! After some frustrating attempts at changing various thing - new coil, condenser, points, plugs and HT leads - it narrowed down to an earthing out on badly insulated connections to the post on which the points are mounted. Grateful thanks to all for helpful input. Now look forward to putting the girl back together and giving her a blast! Andy

Re: French Super Cub Firing Problem

Sun Feb 17, 2013 4:34 pm

I love the different way to say things on each side of the pond. When you say earthing out I think you mean what we would mean by grounding out or shorting out. That would have led to hot wires and smoke with the ignition turned on. I didn't see that in your report so I wonder if you had open or no connection due to dirt and or corrosion.

Doesn't really matter why no spark for you have it fixed.

Re: French Super Cub Firing Problem

Sun Feb 17, 2013 10:31 pm

Glad you have it sorted out, Andy. Thanks for the update as well. Make sure to post some pics as you progress!
Regards, Stan

Re: French Super Cub Firing Problem

Mon Feb 18, 2013 4:08 pm

Thanks for the interest Stan & Bill - hope to load up some photos in due course. By the way - oil pressure is real good - encouraging.

The problem was with the insulator washers on the connections of the condenser and points to the mounting post - no smoke noted!

However - next setback - tractor was running then stalled (not fully re-assembled carb, air intake etc) - forgot to kill the ignition - returned a couple of hours later to find the new 12v oil filled coil had over-heated and exploded - messy business! Battery also fully drained - not my day!

Re-fitted old Ducellier (French) coil that is weeping slightly - again no spark! Suspect this coil has given up the fight. Still to check things out with a volt meter.

Think I may need a ballast resistor coil as indicated in previous posts. Not sure how critical the type of coil might be. However again any thoughts gratefully received.

Andy

Re: French Super Cub Firing Problem

Mon Feb 18, 2013 6:04 pm

Andy the resistor may be built into the coil or it may be mounted seperately and wired into the circuit. Coils do go bad, you must remember that the spark is very high voltage in order to jump the spark plug gap and will jump any defect of the insulation.
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