Spark Advance Engine POWER!

[Steve Ciciora]

  On my '72 Ford 302, the dist. also had two ports: the vaccum advance 
that went to the manifold, and a vaccum retard, that went to the carb
that retarded the dist. under deccel (high vaccum, no throttle, etc).
Well, this is how I rember it, reality might resemble the above...
-Steven Ciciora

> 
> >   Also, for peak power and
> > performance, the vacuum and centrifugal advances should be in good working
> > order and should advance the spark under load or RPMs.  However, in
> > American cars, the vacuum advance is (and has been since about 1972) a
> > vacuum *retard*.  This does reduce NOX emissions but it is detrimental to
> > power and mpg.  Now, I noticed on my '78 Toyota FJ40, that the spark
> > 'advance' assembly has two ports. 
> 
> [big snip]
> 
> > John Brewer
> 
> I wouldn't dream of understanding a Toyota (they are weird), but I DO 
> understand the workings of the GM HEI distributor (all GMs 75-80 something)
> and they have vacuum advance, not retard. 
> 
> Markus Strobl      96 Z28 6M Black.   Borla, !CAGS, 1LE shaft, B&M Shifter
> Dallas, Texas      1.6 rockers, ported heads, Swaybars, SFC, Crane Springs
> F-member 9/93      No times since latest mods               27.5mpg @85mph
>