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Re: What IS Vacuum advance?

To: mgs@Autox.Team.Net
Subject: Re: What IS Vacuum advance?
From: "Matt Milkevitch" <milkm@mail.vt.edu>
Date: Wed, 6 Jan 1999 22:28:59 +0000
> 
> I concur, it definitely smooths the idle. Try disconnecting and plugging the
> line from the the carbs and let the car idle without the vacumn advance. The
> idle tends to surge a little but with the advance connected idle is much
> smoother, I notice this especially at lower RPM 600-900rpm. You will also
> see your timing jumping around a few degrees or so with a strobe light on
> the marks. I guess this is why you are supposed to disconnect the vacumn
> advance line before setting your timing.
> 


In concur as well.  I don't see any appreciable idle difference, but 
by disconnecting my vaccum advance I see a very noticable power 
difference.  This is especially evident in the top end.  Upon 
consultation with a local ex-Leyland mechanic, he informed me that 
the distributor I am using (Lucas 45D4, "eurospec" recurved) produces 
way too much advance at idle (vacuum advance connected), with little 
left over for top end power.  Diabling the vacuum advance appears to 
solve this problem.  I found these comments to be quite 
interesting. not sure if this analysis can be extended to other 
Lucas distributors. 


 Further comments from the group???


            Best Regards,

            Matt Milkevitch

Matthew Milkevitch
Graduate Student, Ph.D. Candidate
Dr. Karen J. Brewer(Chem), Advisor
Dr. Brenda W. Shirley(Biol), Co-Advisor
Va. Tech
Blacksburg, VA  24061
(540) 231-4708


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