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
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