Packard Forum Index » Pre-War (1899-1942)

Planning on installing a tachometer on my Six, to help with properly installing/tuning a replacement carburetor. Where did Packard wire the tachometer to get the "signal" to operate the tach on Packard models that were factory-equipped?

You should follow the instructions on your tach. Probably the wire just wraps around one plug wire by the distributor cap.

I believe the only tachs Packard offered were prewar and were the mechanical type. Those worked somewhat like a speedometer with a gear and cable drive module. The modules could be on the distributor or on the rear of the generator. I think Packard preferred the drive that was on the generator.




If you have found an electronic tach that will work on 6v those would have along with power connections, a signal wire that either connects to the same coil terminal connecting to the distributor or some kind of inductive pickup around a plug or the coil HV wire. If the electronic tach does not specify or supply a wire the reading will probably be more reliable if the wire run between the coil and tach connection or if there is a separate conversion module connection, a shielded wire.

GB -- Howard HH56 is right as always. I had a '40 120 that had the optional '39 tachometer, different face for the junior and senior tachs but both read to 5,000 rpm (! never approach more than 3,600 which is maximum hp, anyway, max torque at 1,800-2,000). Since '40 essentially the same dash, i added it, and it ran off the generator per HH56's above photo; like a T-series MG or very early Corvette.

The tach was a '39-only option since that was the year Packard finally offered overdrive--Chrysler offered it since 1934-- and it dramatically showed the efficacy of this new to Packard option. Overdrive was available on all 1939 Packards other than the 446 leftover Twelves. The final generation 1936-38 Pierce-Arrow 8s and 12s came with overdrive standard, coincentric rings on the speedometer showed the rpm in under and overdrive at various mph.

My '47 Super Clipper has a period 4,500 rpm steering column mounted Stewart-Warner tach. Can't imagine having any manual shift car without a tach. Do you "need" one? Of course not, unless you like engines. A tach, oil pressure, ammeter and temp gauge are all you really need.

FYI:

If you cant find/install one of the original tachometers, this guy in Illinois adjusts Stewart Warner factory tachometers for 6V positive ground. The tach has 4/6/8/10/12 cylinder pulse settings, which he sets up for you prior to shipping:

ebay.com/itm/196661105551?itmmeta=01JC8J ... h=item2dc9ea538f:g:0j4AAOSwYo9nKQQ1

3-wire hookup. Use a 6V +Gd LED for illumination. I am putting mine in my left (driver) 1937 glovebox so all I have to do is open the glovebox door and I can see the tachometer without any ugly steering column or dash modifications and everything looks stock when buttoned up.

It really helps if you drive any highway miles...so I can pick the peak torque/hp crossing point from the dyno chart for efficiency, or if I go above that I also know when I am approaching yellow/redline rpm's (when passing...I have a 12 cylinder with low gear ratio, so I have reserve torque to pass at highway speeds; most 8 cylinders can do the same without overdrive and 6 cylinder Packards need OD to get into this speed realm)

Thanks to all who replied, lots of helpful information. I plan to install a 6V to 12V converter (back in the day I would have just called it a step-up transformer) to power the tach, which will just be a common modern 12V variety. I have heard of Westach, who makes made-to-order tachs. My curiosity was mainly how Packard did the RPM interface. Always something to learn about Packards. I like the idea of an in-the-glovebox mount, keeping the clean stock look.

DM37's ".... so all I have to do is open the glovebox door and I can see the tachometer without any ugly steering column..." puzzles. In my '40 120 i had the '39 tach option since the dashboards were nearly the same.
Having now a tach front and center beats looking over at the glovebox door at the other side of the cockpit.

By the way, the ugly steering column installation in my '47 Super Clipper is Stewart-Warner, and once common in cars owned by serious motorists. It is a benign bolt-on affair. No Packards were harmed in the making of this picture.

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To each his own