Re: XJ-S V12 Archeology (Distributor Questions)

[Michael Neal <mneal@wco.com>]

At 02:58 PM 2/11/97 -0500, John Napoli wrote:
>
>As the result of other work I'm doing on my car (an 82 XJ-S HE) I pulled
>my distributor apart.  I tested the centrifugal advance (free and moving
>properly -- hooray!) and the vacuum advance.
>
>The vacuum advance is dead.  Applying vacuum to the diaphragm results in
>no movement; in fact, the unit will not hold any vacuum at all.  The
>vacuum advance on the distributor from my donor engine behaves the same
>way, so I guess they are both shot.
>
>Questions:  
>
>1.  Is it common for the vacuum advance units to fail?  I've got two, and
>they're both dead.

With the high underhood temps they fail quite regularly.  Note that the new
replacement units don't hold vacuum, they bleed down slowly.

>
>2.  Are the vacuum advances rebuilable?
>
Not that I've seen.


>3.  If not, what is a good (inexpensive) source for a replacement?

Any good Jag parts specialist.

>
>4.  Is there an interchange from another distributer?  Either direct
>bolt-on (I mean pin-on) or by adapting?

I don't think that it would be worth messing with.

>
>5.  If no one knows of an interchange, what are the specs for the stock
>vacuum advance to help me in finding an alternative?
>

>6.  On some V12s, the vacuum advance covers the front right throttle stand
>bolt.  Does this mean that the distributor was not installed 'properly'
>(ie, according to M. Neal's directions in Kirby's book)?

With proper adjustment it should not ever cover this.  The instructions I
wrote work great for me every time.  I didn't even have to adjust the
timing on half of the ones I've done.

>
>7.  I happened to be at my local Jag dealer and enquired about the price
>of the 'Distributor Service Kit' mentioned in Kirby's book.  Of course,
>the parts guy never heard of it.  He would sell me each piece separately,
>though (the distributor o-ring alone is over $8.00 US).  And of course,
>none of it was in stock.  ANyone know of a good mail order source for this
>kit?
>

I remember someone posting a source for this, I need the shaft seal for my
spare distributor.  Does anyone remember the source?


>The reason for question 4 is that if these things commonly quit, I would
>prefer to fit a unit from another car that was less expensive, more
>dependable, or both.
>

One rebuild should last for quite a long time.  A cool retrofit would be to
use the distributorless system from the later 12 cyl.  I believe it was
used on the 6.0 and used two coils with six plug towers on each.  I think
it was Marelli but I haven't seen one of these systems in the flesh yet.


>John


>
>
>

---

References:

• XJ-S V12 Archeology (Distributor Questions)
• From: John Napoli <jgn@li.net>

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