Magnetic pickups for tacks

all it is is a phonic wheel.picks up magnetic impulses generated by the flywheel magnets,and induced into a coil pickup,impulses are read in I computer box and converted to rpm.....

Can the pickup sensor itself be tested for good or bad?

Thanks Gerald . Could this style TACK be connected to the distributor (TACK) term or would that be to much pulse??

The pulse from the distributor coil primary would be too much pulse I think and would happen more often like for a four cylinder engine twice per revolution. There have been test tachometers made to operate on the ignition coil connection to the points, same meters often could also show dwell (fraction of the time the points are closed) needed for some GM engines to set the point gap. I have a meter like that somewhere, but haven't used it in a long time.

Gerald J.

Its measured in hertz. there is an online calculator that converts hertz to rpm. if you buy a tach that measures rpm from a magnetic pick up you will have to input the number of teeth  for it to read correct rpm.  We use them in all of our oil field compression.

If all you need or want is engine speed, get a regular add-on tach made to read the ignition pulses. Unless it is diesel. Otherwise you will need a tach that you can calibrate for number of ring gear teeth.

When the tooth on the flywheel passes the magnet it's converted to a electric pulse. the tach counts the pulses and converts that to a digital signal for the readout. tacks you get will be a tach/ hour meter. They are accurate and trouble free. If the tach ever goes on my 190 I will add the mag pick up and put a digital tach in there. Im sure its better than the factory tack. Thats assuming you aren't a die hard purest. I have already put a timed relay on my manifold heater and it is much better than holding the key backwards and counting.

The alternator generates alternating current with the frequency proportional to the shaft speed so a sample of that is given to the tachometer designed to use that. No pulse sensor. The alternator then uses silicon rectifiers to make DC for charging the battery. Long ago some Leece-Neville alternators used external rectifiers so put out three phase AC.

Gerald J.

Burl wrote: So , the works inside the tack converts the magnetic pulse to RPMs ? The sensor wire only goes thru a selector switch (under tack) before connecting to tack. What I am up to is putting a tack out of a F2 in a K2 that had NO tack or pickups. All I need   or want is engine RPMS. I mounted tack ,bypassed selector sw. Put factory sensor on flywheel and direct wire to tack and hope it will give reading !!

Just curious,why the interest in eng rpm? Almost never check mine but I live by ground speed and that cyl rpm is mighty handy when needing an adjustment.