[Healeys] Austin Healey 100 Misfire Diagnosis.

[Alan Seigrist]

Hi John -

Yes, that was the point I was trying to make, sorry if it fell through bad
interpretation!  As Ed McMahon used to say, "You Are Correct Sir!"

Cheers,

Alan

On Thu, Sep 29, 2022 at 7:53 PM john harper <ah100tech at gmail.com> wrote:

> Alan
>
> Coils can fail with heat and then recover when cooled. I had one that had
> these symptoms and when looking closely I saw that the insulating oil had
> run out through a very small crack in the bottom of the case.
>
> On Thu, 29 Sept 2022 at 10:34, Alan Seigrist <healey.nut at gmail.com> wrote:
>
>> Michael -
>>
>> Just as a follow up to my email since the symptoms seem to manifest
>> themself  ...
>>
>>    - whether the car is warmed up or not - this typically will exclude
>>    anything related to fuel or the coil
>>    - whether the car is under load or not - this typically will exclude
>>    anything related to fuel
>>    - whether the choke is pulled or not - this typically will exclude
>>    anything related to fuel
>>    - somewhat intermittent but systematically under all conditions -
>>    suggests to me wiring / ground issues
>>
>> Given this I'd check (as a priority):
>>
>>    - Battery Master (when these fail they will ground the coil)
>>    - primary ignition wire (white) from the switch to coil (cycle the
>>    connections)
>>    - motor ground straps (cycle the connections)
>>    - loose wires in the dizzy
>>    - loose ignition wires into the dizzy or spark plug
>>
>> Other things to possibly do (as secondary):
>>
>>    - replace rotor
>>    - replace dizzy cap
>>
>> I don't think it would be contacts or condensor simply because this would
>> either be very regular all the time, or maybe sensitive to temp.
>>
>> Best,
>>
>> Alan
>>
>>
>> On Thu, Sep 29, 2022 at 4:46 PM Bob Spidell <bspidell at comcast.net> wrote:
>>
>>> re: "... I don’t recall if that wire is separate from the distributor
>>> wire ..."
>>>
>>> It is (or should be). If the battery switch is in the 'OFF' position it
>>> grounds the coil primary so no spark.
>>>
>>>
>>> On 9/28/2022 8:34 PM, Alan Seigrist wrote:
>>>
>>> Hi Michael -
>>>
>>> Have you tried cycling the connections on the white wire from the
>>> ignition switch to the coil, and also from the coil to the distributor.
>>>
>>> You might also want to try disconnecting the black and white wire at the
>>> coil from the battery master switch - if it’s failing you’ll get weird
>>> symptoms like this.  If that wire is disconnected the car should run no
>>> problem.  I don’t recall if that wire is separate from the distributor
>>> wire, if it isn’t you’ll have to disconnect it from underneath the master
>>> switch itself.
>>>
>>> Best,
>>>
>>> Alan
>>>
>>>
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