[Shotimes] OT: problems on old school Mustang ignition

[Dave]

Mustangworks.com one of my personal fav's
Stangnet.com really big site but don't say anything that may be 
disagreeable to a moderator you'll be BANNED!
and of course the Corral.
I'd say Mustangworks for the simple fact there are more classic stang 
owners over there the could help.


Justin Schick wrote:

>Sorry for the OT but I know there are other Mustang owners, EE's and all
>around smart people on the lists. I know of the Corral forum (where I
>plan to also post) but if anyone can suggest other GOOD lists or forums
>that would be great. I need some help with my Mustang's ignition. The
>car is a '66 with a 408 and AOD.
>
>The previous engine (original 289) had an aftermarket ignition
>consisting of a Mallory Unilite distributor and Promaster coil. It ran
>like this for over five years but did burn out an optic module early on.
>When it was replaced I was told to add a ballast resistor on the
>ignition wire going to the + post of the coil (even though the stock
>wire is supposed to be 1.3-1.4 ohm resistor), and it ran this way until
>I pulled the tired 289. The new engine has a new 351W Unilite
>distributor, using the same coil. Spark is not constant; if I put my
>timing light on the coil wire and crank the engine I'll get no more than
>3 consecutive sparks, with many gaps inbetween.
>
>The Promaster 29440 coil tests out to .6 ohm primary resistance and
>12.41k ohm secondary resistance, supposedly to spec. Battery voltage
>measured 11.85 volts. Ballast resistor on the ignition wire measured 1.1
>ohm.
>
>With everything connected up (resisted ignition wire and red
>distributor wire on the + post of the coil, green distributor wire on
>the - post, and brown to ground) and the ignition turned to ON, I
>measured 7.43v on the ignition post of the starter solenoid (marked I),
>7.22v on the input side of the ballast and 3.5v on the output (+ post)
>side. With the ballast resistor removed and everything connected, I
>measured 4.6v on the + post of the coil and 4.8v on the I post of the
>solenoid.
>
>If I remove the wires from the + post of the coil I get full battery
>voltage on both sides of the ballast and the I post of the solenoid.
>Same thing with the resisted ignition wire directly on the + post and
>with the red distributor wire loose, and vice versa (ignition wire loose
>and red distributor wire on + post).
>
>If both the ignition wire and the red distributor wire are loose from
>the + post of the coil but held together, I get 11.75v on the output
>side of the ballast resistor and full voltage everywhere else.
>
>I am unsure what would cause the voltage drop in the circuit with the
>wires connected up to the + post of the coil, and why the voltage is
>lower all around with the ballast resistor removed. Would a faulty
>ignition switch be a culprit, or should I suspect the old coil even
>though it tests ok? TIA for any thoughts or suggestions.
>_______________________________________________
>Shotimes mailing list
>Shotimes@autox.team.net
>http://www.team.net/mailman/listinfo/shotimes

[demime 0.99d.1 removed an attachment of type text/x-vcard which had a name of showerks.vcf]