Re: Fw: IML: Carter AFB running Question

["Frederick Joslin" <fljoslin@xxxxxxxx>]

The job of the ballast resistor is to vary the voltage that the coil gets so that it does not over heat and fail. The coil needs more power (voltage in this case) at higher RPM when it is firing more sparks per minute and less voltage at lower RPM. My understanding is the the coil will get about 6 volts through the ballast resistor at idle and more at higher RPM.

 

During the starting process the coil is by-passed so it sees the entire voltage from the battery. Too high a voltage at the coil could be a bad ballast resistor (as you appear to have) or a short in the by-passing circuit. 

 

The 45K volt coil that I have uses a much lower resistance ballast resistor than stock, presumably because it requires more power to get to the higher (45K) voltage.

 

I do not know how old your coil is, but when I run into situations like this I like to change out all of the "wear" parts which would include the ballast resistor, coil, condensor etc. 

----- Original Message -----
From: "Chris Strohmeyer"
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Fw: IML: Carter AFB running Question
Date: Wed, 27 Dec 2006 15:16:41 -0800


Look below, Can too much voltage to the coil be making it run erratically?
Chris
----- Original Message ----- From: "Chris Strohmeyer"
To:
Sent: Tuesday, December 26, 2006 6:34 PM
Subject: Re: IML: Carter AFB running Question


> I may have found part of the problem. I
> checked the vacuum and its around 15 which is
> fine.
> But, I checked the voltage at the coil while
> it's running and it's at 12 v. Should be 6v
> right? So I checked it at the ballast
> resistor and it's 12v on one side and 13.5 on
> the other. I think the ballast is wasted?
>
> Your thoughts?
> Chris
> ----- Original Message ----- From: "D. Howland"
> To:
> Sent: Tuesday, December 26, 2006 1:30 PM
> Subject: Re: IML: Carter AFB running Question
>
>
>> Have you tried this:
>> Run it at 2500 rpm. Close the choke plate
>> (or block what you believe to be the
>> offending venturi(s)) with your hand. Does
>> it get better? If you have a fuel starvation
>> issue and you block a bunch of air, it
>> should smooth out as the mixture improves.
>>
>> I'm not sure what the fuel is supposed to
>> look like at that rpm as I'm somewhat timid
>> about sticking my face over a poor running
>> carb at much more than idle. I like my
>> eyebrows intact.
>>
>> Daryl
>> ----- Original Message ----- From: "Chris
>> Strohmeyer"
>> To:
>> Sent: Tuesday, December 26, 2006 1:04 PM
>> Subject: IML: Carter AFB running Question/2
>> Budd calipers on the way fr.calipersonline
>>
>>
>>> Hi again experts,
>>>
>>> I'm having a running problem that I still
>>> think is carburetion. It only idles ok,
>>> and runs erratically at say 2500 rpm.
>>> This is what I've done so far:
>>> Changed distributor, cap,rotor, wires and
>>> plugs. Also have tested it with another
>>> coil-same results. I've checked voltage to
>>> the coil too.
>>> I've checked the compression cold and get
>>> 125 per cylinder across the board. The
>>> engine has about 30 k on it.
>>> I've also sprayed/checked for vacuum leaks, it seems solid.
>>> I have personally rebuilt the carb with a
>>> kit and have had the top off once to check
>>> to if the float level was ok..etc.
>>> What I'm suspicious of the way the fuel
>>> looks going down the primary at a steady
>>> 2500 rpm. It sort of drools unevenly in
>>> both venturis. The "sucking" sound it
>>> makes is not uniform. I thought instead of
>>> slurping or drooling in, it should look
>>> more like a vapor going in.
>>> When I shut it off and look down the carb
>>> it stays dry like the float level isn't too
>>> high.
>>> I rebuilt the carb first because it ran
>>> this way before I did all this stuff. This
>>> still "feels" like a fuel problem. If I
>>> had a spare good carb, that would certainly
>>> prove it.
>>>
>>> Any thoughts?
>>> Thx,
>>> Chris
>>> 67 Imperial Convertible
>>> ----- Original Message ----- From: "Kenyon
>>> Wills"
>>> To:
>>> Sent: Tuesday, December 26, 2006 10:36 AM
>>> Subject: IML: 1967-69 Budd Calipers available soon
>>>
>>>
>>
>>
>>
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>
>
>
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Fred Joslin