>
> Plugged catalyst
>

I guess a possibility, though I would expect to also experience loss of
power under this condition.  I will check it out, though.

> HEAVY carbon build up (unlikely)
>
> Too much advance, BTW, full advance with vacuum is on the order of 40
> degrees btdc, this is ok, as the engine does not see this much advance
> under full throttle.

That's fine then, it appears that mine is well within the normal advance
range.

>
> Lean fuel mixture, possibly on just one cylinder, if you have a plugged
> injector. FYI, I have seen holes burnt in pistons on turbocharged Nissans
> due to plugged injectors.
>

Possible.  None of the spark plugs, however, show evidence of a lean
running condition.

> High internal friction, due to damaged pistons, cylinders, etc, usually
> accompanied by tremendous oil burning.

No excessive oil consumption

>
> too hot a plug possibly?

I don't think so, but I'm not sure.  I'm using the Bosch Super plug, I
believe the number is W8CC.  This same type of plug has been in the van
since I bought it with 99K miles on it.  I just replaced them with brand
new Bosch Supers.  Same plug number.

Sean Bartnik
Johnson City, Tennessee
'81 Vanagon L Westfalia