[Spridgets] Thoughts on the Dizzy/Advamce thingy

[Chris King]

IIRC, that's not quite true, and it also depends on where your vac
source comes from.
 
with a ported (carb) vacuum, I think the highest vac is at part throtle,
advancing the timing for a leaner burn and better fuel efficiency. with
a manifold vac, highest vac is at a closed throttle, mostly for
emissions.
 
When you stomp on it, the vac is low, and only the weights are working,
but you're also addling lots of air and fuel, giving zoom.
 
This is why race dizzys (and the Cooper S dizzy) don't have a vac
advance - no need for part throttle efficciency or emmisions compliance.
 
-=Chris

Chris King
http://home.comcast.net/~kvcbk/ 

 <-----Original Message----->

 	  	 From: Frank Clarici [spritenut at comcast.net]
Sent: 4/18/2008 9:10:37 PM
To: dmg at bossig.com
Cc: spridgets at autox.team.net
Subject: Re: [Spridgets] Thoughts on the Dizzy/Advamce thingy 

Dave G. wrote: 
> SO where does my 'Oomph' come from when there is no vacuum unit and I 
> put my foot down?? 
centrifical advance, it's done with weights on springs that expand when 
they go around faster thus advancing the center of the distributor which
is mounted on a pivot. 

Even the vacuum advance units have weights, when you put your foot down,
you make more vacuum and the tube sucks the diaphram thus moving the 
center of the dizzy. 

-- 
Frank Clarici 
Toms River, NJ 
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