Re: XJ-S V12 Archeology (Distributor Que

[John Goodman <101547.1141@CompuServe.COM>]

John
It's a *Lucas* dizzy, maybe it's worth trying a British car parts 
supplier for the vacuum unit. I *think* the UK spec XJ-S Vacuum unit 
gives more advance than some export versions. Many UK cars have 
interchangable Vacuum units. Try Rover/ Range Rover V8 they look about 
right (just guessing, quick visual inspection only) and various advance 
rates are avalable.

I found this in my data base... if it helps !

>From: "A.T & J Holley" <holley@zeta.org.au>
>To: "'jag-lovers@sn.no'" <jag-lovers@sn.no>
>Subject: XJS Ignition Mods
>Date: Tue, 31 Dec 1996 18:58:41 +-1100
>MIME-Version: 1.0
>Content-Type: text/plain; charset "us-ascii"
>Content-Transfer-Encoding: quoted-printable
>Sender: owner-jag-lovers@sn.no
>Precedence: bulk

> I am writing this at the prompting of a couple of other subscribers . 
  
>My 77 XJS originally had a simple vacuum retard unit that was  
>controlled by a thermo switch on the RH head it gave about 8 deg retard 
 
>when the engine was hot (apparently as a emissions measure).There was 
>no provision for vacuum advance in any form . To me this did not seem a 
>very fuel efficient setup .   
>My first step was to disconnect the vacuum from it and bypass the  
>retard unit , the distributor then just used centrifugal advance with  
>timing set to 10 deg BTDC . Result was cooler running , better fuel  
>consumption and noticably better performance . My next step was to  
>obtain a vacuum unit that gave about 8 deg advance sourced from a UK  
>spec motor . At the same time I fitted a Fuelstar fuel converter ,  
>mainly for this devices ability to allow you to run more ignition  
>advance on unleaded fuel . Base timing at idle (no vacuum to  
>distributor) is set at 10 deg btdc , with vacuum to distributor , 18 
>deg btdc .   
>Mixtures where set to optimum with the aid of a 3 gas analayzer and  
>checked on a rolling road dyno ( both of these in my own workshop,  
>courtesy of the RAAF ).
>I now have a vehicle that does 17mpg (Imperial gallons)at freeway  
>speeds towing a large trailer and I am personally happy with .
>If anyone has any comments , opinions or feedback I would be happy to  
>discuss it with them .    
>I do not talk as an untrained enthusiast but as a trained motor  
>mechanic and motorcycle mechanic who is a Royal Australian Airforce  
>Member who is employed maintaining a large fleet of vehicles .   
>I am always on the look out for other ways of stretching my fuel dollar 
>and I am nowgoing to try the metthods extolled by Kirby Palm as these  
>seem logical and practical.
>  Best wishes   
>    Andrew Holley   

                                            


John Goodman

'89 Jaguar Sport XJR-S 6.0L
'88 Range Rover
'84 VW Camper

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