David is right.  Multiply pulses per second times 30 to get engine RPM.  30
pulses is 900 RPM.

Target Vanagon idle RPM is 880 plus or minus 50, which is 29.33 pulses per
second plus or minus 1.67 pulses.

ICUs working properly typically perform at 850 to 910 RPM, with most
performing at 860 to 900.

Craig in Cupertino

At 11:33 PM 12/3/2013, James wrote:
>Distributor rotates at half crankshaft speed.... idle is 850 rpm....
>half is 425 rpm... one Hall Effect signal per crankshaft rotation ( or
>is that two per rotation...??).... nah, I'd better try to calculate
>this tomorrow!

One pulse per (piston @  TDC** on firing stroke) so two per crankshaft
revolution.

850 rpm / 60  secs/minute = ~14 rev/second x 2 pulses/rev = ~28
pulses/second.

** Really at the fixed timing advance point which is a few degrees before
TDC on the 2.1l.