Reply to "4410 artical"

Here's Holley's view:
If the vehicle has a manual transmission, take
the vacuum reading with the engine thoroughly warmed up and
at idle. If the vehicle is equipped with an automatic transmission,
take the vacuum reading with the engine thoroughly
warmed up and idling in gear. In either case, the power valve
selected should be 1/2 the intake manifold vacuum reading
taken. EXAMPLE: 13” Hg vacuum reading divided by 2 = 6.5
power valve. If your reading divided by 2 lands on an even
number you should select the next lowest power valve. EXAMPLE:
8” Hg vacuum reading divided by 2 = 4 power valve.
Since there is no #4 power valve you should use a 3.5.

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A few comments:
-Your PV would not be continually open if you had a 6.5 and a 13 idle, it opens when the engine produces less than 6.5
-Acc pump works on throttle position only, PV on vacuum only. So going up a long steep hill could mean no acc pump help but PV constantly adding fuel (as it should be)
-It's rare the engine runs only on the jets, because up to approx 60 mph the idle circuit still contributes

Just my $0.02