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Discussion Starter #1
Any clever ideas very much appreciated. As you will note from the below, I am not a mechanic, nor an autoelectrician, and rely on the expertise and advice of others. I do my best with learning as I go on.

The weekend of 26 January, I drove the 1934 Phantom II a glorious 96 miles, 65 or so of which was on Sunday on a run with the Jaguar Club.

Apart from a slight misfire, which had been manifesting before, and for which I was intending to have the plugs blasted clean in due course, all was excellent. This included a few stops and switch-offs, including a long stop for breakfast.

On the return journey, she suddenly started feeling as if she had fuel starvation on the highway. Every now and then the power would go and it would feel like fuel delivery was not great, or something similar. The closer I got to home, the worse this started getting. As the fuel gauge was faulty, and I had done 93 miles since last filling her, and she had a bit of an overflow fuel leak when the tank was very full, I thought perhaps she was running out of fuel. So I added 30 litres (not wanting to overfill given overflow issues). The attendant said he could see the fuel level, but I could not. Be that as it may, she then manifested the "fuel starvation" problem heavily on the next start, until she cut out at the lights some 100m down the road from the station. Starter turning nicely, but no firing engine. This happened for about 10 very nervy minutes, with taking and then retrieving emergency triangle from down the road (no companions). Engine started up again (thank goodness), and she drove to the underground parking garage where I keep her weekends, what with intermittent "fuel starvation" all the way there. Arrived there, she suddenly idled quite nicely.

Remember there was a slight misfire. When I was testing the ignition for the misfire the weekend before, it appeared the misfire was in the battery plugs, as she idled very smoothly on magneto but misfired on battery, so driving on M & B saw her misfire a bit.

Anyway, idling in the parking garage after this disquieting return journey, I played with the ignition advance and retard a bit and found the best spot to be about exactly half. This was standard for her performance since I've had her.

I then switched her off after parking. On trying to restart her about 30 minutes later, I could not get her going at all, whether with choke on "running" with throttle use, or "extra oil and rich" or "starting" with or without throttle use.

Previously, I was advised there had been an occasional problem getting her going if the Autovac unit did not fill properly - this would occur if the carburetter float bowl was empty (tested with thin screwdriver), and one then needed to prime the Autovac with fuel through a screwhole that had been drilled for this purpose (before I got the car - let's not go there). I had never myself had this problem the 9 times or so I had driven her - she had started properly every time. Anyway, I checked the float bowl, which was buoyant, suggesting this was not an Autovac filling issue, but filled the Autovac anyway with fuel. No joy.

My mechanic said this sounded like a fuel blockage somewhere. I readily agreed, as this was very similar to the problems I experienced in the E Type until I had the fuel system flushed and the fuel tank properly lined.

When my mechanic attended a few days later, the fuel filter showed clean fuel, the starter still turned nicely, but there was no spark at all. The coil did not heat up at all. But the magneto also produced no spark at all.

Tomorrow, we are going to try a new coil and condenser.

But I am told the magneto system and coil (battery) system are entirely independent, meaning the magneto and coil appear to have failed simultaneously. This sounds very unlikely to me. Is there some electrical point prior to both magneto and coil that could be responsible for lack of spark from both magneto and coil?? I would hate to go to electronic ignition and essentially abandon the magneto if the fault is somewhere earlier in the system.

I would sincerely appreciate advice on this issue before my mechanic attends tomorrow at around 08.00 am GMT. I'll look again late tonight and hope for some insight.
 

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Get yourself a test lamp. When it won't start, place the test lamp probe on the coil 6 volt feed and confirm power there. Crank over the engine with the test lamp attached. The lamp should flash quickly if the points are working. If that is the case, check for spark from the coil to distributor. Pull the coil high tension wire from the cap and check for fast spark there while cranking the engine over. If the coil is working you will see a regular fast spark. Best way to test for spark is to get a cheap spark tester rather than pulling off a lead. If you have spark at the coil lead, plug it back into the cap and check for spark at a plug lead. If regular spark there you have a fuel problem or fouled plugs. No spark there probably a failed rotor. This is the best way to determine whether the fault is spark or fuel. Spark faults are way more common than fuel issues. A weak coil may work OK when cold or at idle, but the hotter it gets and the more load put on the engine the worse it will misfire. If it stays cold with the key switched on it possibly is not getting power from the ignition switch. Try hot wiring it. No power to coil or no spark from magneto, probably an ignition switch fault. Are you testing for spark from the mag and coil at the plugs by holding a lead close to the block? No spark from the mag at a plug lead?
If you have no firing of the engine without testing for actual spark at a pulled off plug lead perhaps the plugs are now fouled from trying to start with a bad coil. Pull them and make sure they are clean and dry.
A switchbox fault could prevent both the mag and coil firing. Remove the grounding wire from the mag and see if you get spark at the plugs. If not the mag has possibly failed. You should never change the timing trying to cure a miss. Timing off spec will result in a loss of power, not an engine miss, and can cause difficult starting if too far off.
 

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Discussion Starter #4
Thanks guys, especially Jim - will take this into tomorrow.

Ta!
 

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Discussion Starter #5
Report back: it was the coil. The magneto works in idle, but is too weak to start her. The firing is now much more even too. Drove her 5 miles with a few switch offs. All good. Will take my mom somewhere for breakfast tomorrow. Not too far. Say all in a 50 mile trip tomorrow. This has made my week.
 

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Discussion Starter #9
so far so good again

25 Miles this morning - all good, although she still puffs every now and then when coasting at 'speed' (say 50 - 60 mph). Not quite Chitty Chitty Bang Bang, yet. Will get the plugs sand-blasted. Idle is very smooth, and when nice and warm, can go down really low (I reckon as low as 400 RPM) without showing battery light for charging. Mastering the shifts up and down into second without a grind quite well now (still needing to take huge breaths and holidays in neutral a bit on upshifting, to the annoyance of those behind).

If there is no rain tomorrow, and I get a chance, I can finally take her back to her storage chaps for her weekday stables.

Regards and good night to all.
 

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Discussion Starter #10
bypassing ballast resistor - dat ok?

Ok, further feedback:

New coil was starting to struggle to start, and so now I've been told bypassing the ballast resistor cured the problem. Apparently the new coils work on a constant 12V, whereas the ballast resistor was necessary for the old coils.

I understand the ballast resistor to work like a regulator on a generator, which suppresses charge to avoid draining the battery or overloading.

Is there now a risk of draining or overloading the battery with the bypassing of the ballast resistor?

Regards
Frank
 

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Discussion Starter #11
Further Feedback - all well for now

Drove her 35 miles or so yesterday morning - stopped at home for a bit, stopped at breakfast, stopped at fuel station, all restarted perfectly. Idle is great, and running fine, although she puffs a bit when coasting - next stop ultrasonic cleaning of carbs. Doing under 30 litres per 100km (which is a lot, but pretty much what the Corniche is doing in heavy traffic). That's about 9.5mpg, which is probably to be expected with 7.65 litres displacement. Too early to tell.
 

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My understanding of the main function of the ballast resistor is that it reduces the voltage to the contact breaker points and protects them from early wear or pitting. When starting up the ballast resistor is bypassed but once the engine is running the ballast resistor comes into play. I reckon that with the limited mileage you seem to be doing it would take forever for the contact breaker points to wear anyway so contact breaker points wear as a result of bypassing the ballast resistor probably isn't something to be concerned about. However, I'm not very experienced with electrical stuff and am open to contrary opinion.
 

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The ballast resistor is to cut down on current (or amperage), not voltage.

When a car is idling, the points stay closed longer as apposed to when driving down the road at speed, so at idle, more current is flowing through the coil, so much so that it heats up and it would eventually burn out.
So a resistor is put in series to cut down on the current flow, this works well because at higher current flow, the resistor heats up and cuts down on the flow current, thus reducing the load on the coil.

Only 1.5 ohm coils have a resistor in series with the primary windings, now in Vonkie's case, he now has a 3 ohm coil, so an external resistor is not necessary.
There is enough resistance in the primary windings of 3 ohms to keep the coil from over heating at a slow idle.
3 ohms is achieved in a 3 ohm coil with more windings with in and does not require an external resistor.

So with a 1.5 ohm coil when driving faster, the points stay closed less, so now less current is flowing through the primary windings.
When the this happens, the resistor cools down and allows more current to flow through the primary windings and maintaining a good spark at highway speeds.

And ShadowII, the condenser is what does the job of protecting the points from pitting and burning.
The condenser acts like an electrical cushion, absorbing the arc, when the field collapses in the coil when the points open.
 

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ShadowII, you are correct however, the ballast resistor is bypassed to provide 100% of current flow to the primary windings to provide good spark while cranking.
 

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Discussion Starter #16
Ballast Resistor bypassed

Thanks to both, especially Jeff 1.

So it seems that with the 3 ohm coil the BR is superfluous, which is a relief to hear.

Wish me luck on the week-end. It is my 50th birthday, and my brother and I plan to drive the Phantom II and the Derby Bentley together in the morning, followed by lunch with extended family. Since I plan to have champagne flow at lunch, we do not plan to drive the Phantom and Bentley to the lunch, as we would need to drive them back. Let's hope it does not turn into one of those days, rather than the lunch we had planned.

Below is Queen Igry (Phantom) having a sunny breakfast last weekend, and my brother's Bentley doing the same in January.
 

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Hi do you have the Cars (owners) manual for the 1934. It should go to great length to tell you about the use the coil system and magneto system
You can drive on one or the other and both at same time. They should work equally as well as each other.
When you switch on the coil. You using power from the battery. When you use the magneto.Place ignition in run positions. You are disconnecting the ground from the magneto. The magneto switch shorts the magneto to ground stop the spark (engine) Check the point gap on both coil and magneto.
 
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