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Lucas strikes again...curses

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Royal_58

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Curses Lord Lucas

I have been enjoying driving my TR3A this spring which has included a good bit of reliable miles under her belt. Made one road rally and drove most of the day on a "treasure hunt". I was just getting to feel that the rough ol' girl was reliable enough for a moderate cross country trip. On the way to pick up my son at school she left me on the side of the road without a spark. No spare coil in the boot so I had to be rescued and towed home. I know I should have shined her up and cleaned the windows before departure. I also missed our clubs "drive through history"....Curses Lord Lucas

My coil seems to have burned up. What makes that happen anyway? Trying to be proactive, I replaced the made in Japan coil with a Lucas from Moss or TRF. I don't have any idea how many miles I put on it but I know not enough for a failure. So back on with the old MIJ coil with resistor and see what happens.

What causes coils to fail?
Why does the old coil have a resistor on it?
Is it good to replace the lucas distributor with a Petro electronic ignition and coil with the Flamethrower?
What do I need to do to keep from burning up another coil?

<span style="text-decoration: underline">Details</span>:
Positive ground
Running Lucas Dist. with points
Spark advance not working (cracked bellows)
Spare coil ordered

Curses Lord Lucas!
 
It's an electronic part.
A transformer, to be exact.
Parts fail.

Insulation breakdown, improper strain relief on wires, oil insulation leaks out, extended very high heat, plug gap too wide, wires breaking down, any and/or all can contribute

Plugs and wires can cause the internal voltage to go higher to effectively jump the gap on the plugs, increasing the chances of internal arcing.
 
Could a condensor cause an overload?

The wires are new as well as the cap and rotor.
Spark plugs were gapped IAW with maintenance manual and were a few weeks old.
No oil leaks from coil.

Thanks for the tip on the heat. I'll fabricate a shield from the motor!
 
Your old coil had a resistor because most cars after 1970 or so used a resistor in the coil circuit. They were equipped with a circuit to bypass the resistor while starting, to provide a hotter spark when the battery voltage was low. The "external ballast required" coils are a common replacement part, available in any auto parts store.

In fact, you need to be careful to get the right Lucas coil, as Lucas makes both kinds (and later Triumphs have a ballast resistor built into the wiring harness).

Sounds like your new Lucas coil was simply defective, most likely IMO an internal wire was not supported properly and engine vibration caused it to eventually fatigue and break. Defective replacement parts are all too common these days, even when they bear "known" brand names. Ken at British Frame and Engine once told of getting in a case of Lucas coils where over half were either DOA or didn't pass muster on a tester. Of course, the Lucas name has been sold several times since then, so YMMV.

However, it wouldn't hurt to check your plug wires with an ohmmeter, to be sure there isn't a hidden bad spot.
 
Duke:

When I purchased my 58 TR3A it had the lucas coil and points on it which ended up going out. I installed an electronic ignition and a flame-thrower coil; kept the postive ground and haven't had any problems with it. This will be the 25th year I've owned the car. I'm not a purest when it comes to my cars, sometimes new technology is just better.

Terry

58 TR3A
76 tr6/with surrey top
 
Terry - The coil and distributor on my 1958 TR3A are the original ones. They have never failed me. Older parts and technology can be just as reliable. The TR has over 183,000 miles on it.
 

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Royal_58 said:
...What do I need to do to keep from burning up another coil?
Click to expand...

Carry a spare -- I find that usually guarantees that the problem does not recur.

Like Don, I have an very old Lucas coil that still works though it is now my spare as I have a Lucas Sport coil. Went through one of those pretty quick, then got a good one next time.
 
Heat is a big enemy of coils.I suggest using a small insulator to keep some of the block heat from soaking the coil.Its a little known fact but the factory only put a limited number of sparks into each coil when it was built!! When they are gone, they are gone!(and you be walkin)
MD(mad dog)
 
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