Re: Vaccuum Advance on '71 Scout

["Tom Harais" <tjhemh@domain.elided>]

Michael:

If the engine didn't "miss" when your timing light did, I would suspect the
ability of the timing light clamp to pick up the spark on those wires was
at fault, not the ability of those wires to transmit "spark" to the plugs.
That is why I want you to check the resistance on those plug wires - to see
if they are any good.

As plug wires age, they can get internal breaks and thier resistance can
increase to the point where they actually will not carry a 12,000 or so
volt signal to the plug. I know I had the set on my Honda do this and they
looked almost as good as new! I checked the resistance and found that all
four measured infinite resistance no matter what I did. Replacing them
solved my engine missing problem and the fuel mileage returned to normal.
And, beleive me, I didn't want to consider the plug wires as a culprit at
all. It just didn't seem like they could get so bad as to completely resist
that high voltage current that comes out of an auto ignitions secondary
circuit!

Tom H.