Jose,

Did you replace the condensor?  It prevents arcing across the points, 
which could happen if your points are old and worn.  You also don't state 
what condition the rotor is in.  Also check the resistance across the 
coil, if out of spec replace.  You said that you saw the spark advance 
when you rev the engine but double check the weights inside the 
distributor for movement.  Spray liberally with WD40 if dry.  Run the 
engine at night and watch for sparks jumping the gap where they shouldn't be.

If those steps don't do it then it's time to look for gremlins.  I hear 
they're having a sale on BGMs at Checker (Bosch Gremlin Meter).

Jack

On Tue, 17 Oct 1995, Jose Antonio Madriz wrote:

> Time to seek for the vanagoners (vanagonians?) expertise...
> 
> What i thought initially to be a carburator problem in my '73 bus is
> manifesting now as a spark/distributor problem. My bus seems to be
> running in 3 cylinders, maybe 2. After checking the spark from the
> distributor with an inductive light i noticed that cylinders 2 and 4
> were getting a spark unevenly and once in a while... when taking the
> wire plugs from cylinders 1 or 3 the engine dies, whereas if i take
> the wire plugs from 2 or 4 (or both), the engine doesn't change revs
> at all and keeps running as before. Now, if i hold #4 wire right next
> to its distributor hole, the cylinder starts catching sparks and the
> engine seems to make an effort in increasing revs...
> 
> The points seem to be set correctly (dwell ~50 and remains +-1 when
> increasing revs). I thought it might have been a problem with the old
> and filthy spark plug wires that the bus had when i bought it, but
> this morning i replaced them with new ones and the problem is still
> there. I also changed the distributor cap, but didn't help. I'm not
> sure where to go from here... could it be a bad condenser? The
> distributor is a 009 mechanical advance. Any ideas?
> 
> Thanks!
> 
> Jose A. Madriz 
> '73 bus (weak Shaggy)
>