[DeTomaso] vacuum advance

[Andy May]

In my experience a good place to start with vacuum advance is about 20 deg
at the crank. However, you need to get the initial and total mechanical
right without vacuum first or you'll just end up chasing your tail.

I go to a traffic free place and do some full power runs on a reasonably
level road to set the mechanical, finding the maximum advance I can get
away with before detonation then back it out a couple of degrees. Once this
is done I go and find a good hill and connect the vacuum. Climbing the hill
with only moderate throttle, adjust the vacuum canister so it just stops
detonating - then back it off another 2 full turns. Nobody can give you
precise settings for your engine as there are too many variables involved,
especially if its been modified from stock. The above process will get you
very close to where you need to be.

I always connect vacuum advance to ported, not manifold. Others will
disagree I'm sure, but you'll probably see way too much advance at idle for
most applications with manifold vacuum.

Kind regards

Andy
On Aug 31, 2012 12:39 PM, <dennis617 at aol.com> wrote:

> So I just got my new replacement vacuum advance for my Mallory Unilite
> distributor and it appears that the advance I'm getting at full manifold
> vacuum is way too high, around 24-25 degrees (plus the initial 16 degrees
> for a total of 40-41 degrees at full vacuum).  Does anyone know what the
> total vacuum advance is supposed to give so I can adjust it, at least for a
> starting point.  Right now she is backfiring all over the place.
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