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Thread: Coil problem?

  1. #1
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    Coil problem?

    I replaced my dual point Mallory ignition system with a Pertronix Ignitor ll and Flamethrower coil some time ago and was very impressed with the improvement. The pick up through the gears was much better and would pull smoothly in 5th gear from 1500 rpm....until now. It now feels as though it should be in a lower gear to run smoothly. I did notice some oil around the base of the coil a while ago so put a smear of epoxy resin around the lip. In my experience coils usually just pack up and the engine won’t run. Is it possible they can partially work? Can they be tested under normal operating temperatures?
    Dek

  2. #2
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    Dek,

    Try putting a multimeter across the terminals (disconnected from the car wiring), if I recall correctly most Flamethrowers are 1.5ohms. Less than this means that the internal coil wiring has started breaking down, i.e internal short circuits. I did hear that there was some quality problems with the coils when they were sourced from the Far East many years ago but I'm not sure how they exactly failed.

    Russ.
    Joint Area Rep - East Midlands Region
    1984 DAX Cobra
    Rover 3.5 V8 with Holley carburetor.

  3. #3
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    Quote Originally Posted by Russ-Notts View Post
    Dek,

    Try putting a multimeter across the terminals (disconnected from the car wiring), if I recall correctly most Flamethrowers are 1.5ohms. Less than this means that the internal coil wiring has started breaking down, i.e internal short circuits. I did hear that there was some quality problems with the coils when they were sourced from the Far East many years ago but I'm not sure how they exactly failed.

    Russ.
    Thanks Russ. I’m pretty sure you are right, it is a 1.5 ohm so I’ll get the meter on it. I also read on some USA forums some from the Far East were failing. Got mine directly from Pertronix Europe so surprised it may have gone but it is mounted on the inlet manifold so must get hot. Epoxy filled ones are available which may be more resistant to heat or relocate it? Always tempting to put it close to the distributor.
    Dek

  4. #4
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    If it's mounted on the inlet manifold which way up is it ? As they aren't supposed to like being layed down on their sides.

  5. #5
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    Epoxy coils are more resistant to vibration and orientation, IIRC. I didn't think there was an improved temperature performance with epoxy filled coils, but I might be wrong...
    --
    Richard
    GD Mk3 LS6

  6. #6
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    Quote Originally Posted by TINKA View Post
    If it's mounted on the inlet manifold which way up is it ? As they aren't supposed to like being layed down on their sides.
    I think I remember that one as well Martin so it’s vertical.
    Cheers.
    Dek

  7. #7
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    Quote Originally Posted by richard8166 View Post
    Epoxy coils are more resistant to vibration and orientation, IIRC. I didn't think there was an improved temperature performance with epoxy filled coils, but I might be wrong...
    You’re correct as well Richard having just discussed it with Pertronix. Like you say ideal for off road and racing applications.
    Thanks.
    Dek

  8. #8
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    Dek,

    I've had a Flamethrower coil for around 10 years. Mounted vertically and clamped to the front chassis cross member. Nice and low down, in a good airflow and the chassis acts as a heatsink. No problems, touchwood .

    Russ.
    Joint Area Rep - East Midlands Region
    1984 DAX Cobra
    Rover 3.5 V8 with Holley carburetor.

  9. #9
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    Yes, coils usually work or don't work. Typically they can have a break in the primary winding where the edges of the wire still touch each other. Once warmed up, the break opens up and there is no spark. Mind you, all kinds of failures are possible.

    You mentioned that it's an Ignitor II. That unit is supposed to use a 0.6 ohm coil. You might want to look up the coil you're using starting on this page:

    http://www.pertronix.com/prod/ig/default.aspx

    I've never found it terribly useful to measure a coil's winding resistance other than took for an open. Making a resistance measurement on the primary usually isn't all that accurate and readings can vary drastically when measuring the secondary, even on a known good coil.

    I have heard some bad things about the Ignitor II modules. I using the basic Ignitor unit with a 1.5 ohm coil and it's fine, although barely. I think I'd look at an Ignitor III next time.

    Dirty or worn sparkplugs could be causing your problem, but I never underestimate the value of new ignition wires. Old wires can really cause trouble, even if they're only two years old (some people say 1 year).
    John

    my world... my universe... my garage.

  10. #10
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    Thanks John
    I took advice from Pertronix UK before I ordered from them so I hope they sold me the correct combination of coil and Ignitor. I did retain the ballast resistor in the circuit on their advice. I also measured the resistance and it was 1.6 ohms but that only tells me what I already know, that it hasn’t totally failed. I totally agree with you on the plugs and leads. Both were changed last year, that’s why I’m looking at the coil. For a fairly modest cost to replace if it’s not the problem at least I have a spare to carry around in the event of total failure. All the best.
    Dek

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