Miss

["John Hofstetter" <hofs@domain.elided>]

Russ,
Depending on how you define "miss", I would assume the problem is
ignition. (Plug  or plug wire)  Do you have resistance wires for radio
static interference? These, as you probably know, are a frequent cause
of missing.  Because I've gotten lazy, I prefer to take my vehicle to
my son who uses his (actually mine) old Marquette oscilloscope to
check out the condition of the whole ignition system.  Most any of
these analyzers, even the very old ones, will short out the plugs one
by one, to help make an easier diagnosis.  The fact that you pulled
the manifold certainly could mean that you inadvertently damaged one
of the wires. 

May I suggest that if you decide to not try to find someone with an
analyzer who will check the whole thing out cheaply, that you check
the wires with an ohmmeter, assuming that they are resistance wires. 
In my experience, modern wires are much more likely to cause a miss
than plugs, if the plugs are in good shape.  Also, both plugs and
wires are more likely to miss under load, than they are at idle or
slow rpms. Under these conditions, the spark seeks a lower resistance
outlet than the plug gap. It's not relevant to much of anything, but
back when we used to clean plugs routinely with a sand blaster, we
would visually inspect the spark with high pressure air blowing by the
gap. I don't use my sandblaster cleaner much at all anymore, but still
stick my plugs in the tester and turn on both the spark and the air. 

In testing the wires with an ohmmeter, look for consistency in the
ratio of ohms/length. That is if the wire is twice as long as another,
its resistance should be about twice as much. Hope this helps, and
that my babbling didn't bother you.
John Hofstetter
----------
From: owner-ihc-digest@domain.elided (ihc-digest)
To: ihc-digest@domain.elided
Subject: ihc-digest V6 #776
Date: Mon, Apr 26, 1999, 11:14 AM


From: Russel DeArman <russde_93@domain.elided>
Subject: carb? or points?

  Since pulling the intake mainifold off to fix the
tappet cover gasket my Scout (304) has run ragged. It
sounds like it is missing.
  I have replaced the cap and rotor, checked the point
gap, re-timed, pulled the top of the carb and adjusted
the float level, adjusted the idle a/f, and checked
continuity on all the plug wires. 
  My plan next is to pull all the spark plug wires
individually (anybody know a good way to do this, and
NOT end up with a numb hand?)to see if all the
cylinders are firing.
  The missing manifests most noticably when
accelerating off the line, the truck has a three speed
which has a really tall first gear so I have to rev
pretty high to keep from stalling. I can hear the
'miss' if I raise the rpm's in the driveway as well.
  Does this sound like spark or more like a fuel
problem? 
TIA,


===
Russ D.
'73 Scout II 304
San Antonio, TX