And remember to block off the vacuum advance hose before setting the advance
with your timing light.
Todd Osborn wrote:
> Jim,
> Adding to Gordon's info -- you do not add the vacuum advance to
> determine total advance, initial plus centrifical should be less than 35
> degrees. Vacuum advance only comes into play at partial throttle and
> light load. It's really there to improve cruise mileage, has to do with
> charge dilution by exhast gas, Tom can explain it ;-)
> Todd Osborn
> 68 DATSFUN
>
> Gordon Glasgow wrote:
> >
> > Jim, the 7.5 on the distributor cam means 7.5 degrees at the distributor.
>But remember the
> > distributor is driven at 1/2 crank speed. That makes it 15 degrees at the
>crank. Add that to the 20
> > degrees initial specified for the Solex cam setup and you have 35 degrees
>total.
> >
> > The smog distributor cam was 17.5 which means 35 crank degrees. That was
>when they used 0 initial
> > advance, again for a total of 35 degrees.
> >
> > HIGHKIX4@aol.com wrote:
> >
> > > For all:
> > > Was installing my new vacuum advance unit and looked under
> > > the breaker plate. Centrifugal advance mechanism has
> > > 7.5 stamped on it. Doing the math, with the non smog
> > > distributor calling for about 10 deg initial advance, then this
> > > one will give 17.5 at wide open throttle (no vacuum) and
> > > med revs or higher. This would seem about right for not
> > > burning pistons (as much discussed recently), so then is this a
> > > non smog distributor?? And when I put everything
> > > together was happy to see the vacuum advance work
> > > quite nice and smooth when I sucked on the
> > > carb vacuum line, am curious how much additional advance
> > > is added with this, looks like quite a bit
> > > (15 or 20 degrees??). I agree with the previous
> > > posts about total advance never to exceed 35-37
> > > degrees, and this is about true for many or most
> > > engines, so 15 or 20 degrees would be about
> > > right here also.
> > > Thanks!
> > > Jim,
> > > Chesapeake Va
> > > 67 pushrod 2L
> > > 72 510 wagon
> >
> > --
> > Gordon Glasgow
> > http://www.gordon-glasgow.org
--
Gordon Glasgow
http://www.gordon-glasgow.org
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