Hi Gus,

Does the AFM see all the airflow into the engine or is it attached to the
manifold.

>From the picture you linked to i assumed that this thing sits in the path
of all the airflow into the engine.  Is this the case.

I remember I was puzzled for some time when I tried to understand vacuum
advance as i knew that the vaccum falls away to nothing at cruise and at
high acceleration.  At cruise or acceleration I considered that there would
still be a requirement for advanced timing but the fact that there was
little vacuum at cruise or acceleration seemed to be a contradiction.

It wasn't until I noticed that the vacuum pickup line was taken from the
base of the carby body where at high cruise or high acceleration there is
an increased volume of air passing thru.  High volume thru the venturi
equals high vacuum and vacuum advance to assist the mechanical advance.

I suspect you may be aware of this but it may help explain what you are
witnessing if your device is attached to the manifold rather than directly
in the path of  all the air intake.

Justin

On 6 November 2015 at 04:14, 99guspuppet <yes@nope9.com> wrote:

> I mentioned that I opened up my AFM.
> I expected the wiper on the AFM potentiometer to
> track the engine RPM as I assumed RPM and airflow were
> linked proportionally.
> Instead I saw the wiper move up with increasing RPM,
> then drop back.  Since the RPM was hard to control
> ( the reason why I am looking at engine parts ) I was unable
> to make a reliable observation of exactly what happened.
> Any comments ?
>
> Gus in Denver
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.