Early tachometers - Teach and Win!

Ryan, there is a guy here in Mustang that converted a 51 Chevy speedo into a tach using a Corvette dist driven tach generator. Pretty wierd.

 

Stewart Warner (actually Stewart before SW) has made tachometers about as long as they have made speedometers. Just didn't get installed in cars until the performance guys first put them in their hotrods.

The earliest SW mechanical tachs used in hotrods were either low RPM (4000) from a utilitarian purpose, or converted to higher RPM. In the earliest Hot Rod magazines you can find ads from the Maring Company with SW speedos and tachs converted to higher speed (140) and RPM (8000) for use by the racers. That would date them to around 1948, but I bet they were produced a while before then.

SW did produce 8000 tachs in the early size canister (3-1/4"?), but I think they didn't come out till the hotrod market caught their eye. I'd say around 1948 too. Or maybe they just used some airplane magnets in the automotive case. They were a OEM for many different aircraft too.

The oldest electric tach I own is a winged 8000 original from SW. I haven't checked the date on the back, but it would have to have been made between 1948ish to 1954ish. I don't have a sender, the small motor sandwiched under the distributor cap, so I haven't tried it.

I think with any of these SW products, they were as accurate as was produced in those days. Stewart Warner was a very large and prominent company, and they didn't get that way making junk. Course, nowadays it's a different story. But that's not saying they will stay a large and prominent company.

 

I have a S-W mech tach. 9000 rpm, @ 3 3/4" in dia., small white numerals on a black face. The chrome bezel is a little rusty and the #'s are faded. I'm 'guessing' it's from the early-mid 60's.
I'll post a pic when I get home tonight.
Also the tach in my PU is a mechanical S-W 4000 rpm, diesel tach out of a 6x6 or Hum-Vee. But it's fairly new. Plastic housing. Works good though. Cable connection is the same on both, so I can swap 'em if I feel like changing it up.

 

Here is one that used the sender under the dizzy cap. They are twice as deep as a standard tach. on the back side. I have no idea what year it is.

I have what I believe to be an old cable driven SW tach but I don't know what year it is either.

 

I had a new S-W mechanical tach on my 50 Ford sedan - first car.

I worked at a parts house summer of 56 and got to be a bit of an instrument junky -- and still am.
No small wonder, I made a good wage for what I did and everything was half price.

It was like working in a candy store, cept it wasn't exactly work, more like fun considering one of the delivery pickups I drove was a 40 Ford with floorshift, blackwalls, small hubcaps and pipes.
A real sweetheart of a truck that had the sound.
Nothing quite like a pair of steel-packs on a flatmotor.

Anyhoo, what was interesting about the S-W tach was the mechanical drive adapter that adapted the tach cable - which looked very much like a Speedo cable - to the 50's flatmotor.
The adapter was an easily spotted underhood piece that was molded from a beige colored Bakelite plastic and went between distributor body and cap.

(For those not aware, the earlier flats had the distributor on the front center of the engine and the later ones had it on the front right side. The distributor looked like and was mechanically similar to any late OHV points distributor you see nowadays.)

Installation went like this:
Remove distributor cap.
Remove rotor.
Align drive mechanism adapter where the cap went - it snapped on like a dist cap and you had to set it in the right place (like you would a rotor) so it would slide into place.
Then snap the - similar to the distributor - clips into place to hold it down.

Next up was tightening the drive retainer nut so there was no play where the drive mechanism adapters central drive device (call it a shaft) connected to the rotor.
You had to be careful here because you could overtighten the locknut and make the central drive device shaft slip on the original rotors flat spot then when the rotor & cap were installed you'd be out of time.

One time was enough for most guys.
After that, it was use the right wrenches -- one for backup and the other to tighten the locknut.
Snug the locknut down then install rotor on top of the central drive device drive shaft and install the distributor cap.

It was simpler than it sounds and all you had to do was be careful.

After the drive device/distributor were together as a unit you snaked the drive cable/housing into place and screwed it to the tach.

Last step was to screw the cable/housing to the drive device, hook up the tach light and fire it up to see how things worked.

Right at five grand was the top end for a stock flathead - mine anyway - that at the time had nothing more than a pair of pipes installed as the first of many steps learning about and installing speed equipment.

Quarter mile times with that combo was 65-66 mph @ 20 seconds.

A better coil and a set of triple 94's took the car to 70 mph and 19 seconds.

At the time, if you could get a street car to run 100 mph in the quarter you really had something.
It seemed to be a barrier that held quite a few back.

It did us.
Eventually we got there.
All it took was a built Rocket motor, Caddy trans, 4.27 gears, ignition, headers and a few other little things.

For a while we thought we could get the 3100# sedan up to 100 with the flatmotor.
We knew we'd need a stroker, cam, etc.

We knew too that the speeds we wanted to attain were just over the horizon and once we reached that we'd be in Fat City.

We got there, but ended up so broke that Fat City was nowhere to be seen....

 

some mid 50's corvettes had a cable driven tech that ran off of the generator, pretty neat.

 

I do not know much about the older tachs ... but this one came in my 32 3W ...

 

Generator or the distributor?

 

I'd say that dist. cap sender tach style ran early fifties. They are advertised in 54, but I don't see em in 50.
The tough part is finding the correct cap sender nowadays.
And the Marings actually ran to 180 (I've had a couple).

 

I've NEVER seen one of these, and I have pounds of original SW catalogs, manuals, newsletters, etc.

Are you sure you aren't mixing up the electric sender with the mechanical sender? I know, your story doesn't sound like it (in fact it sounds like you did it yesterday). I've never seen a mechanical sender (drive) that wasn't made of some kind of metal.

And yes Root, some manufacturers did do tach drives off the back of the generator.

 

Well, it was a 57 I think that I saw at a show a few weeks ago, it was all stock. There was what looked like a thin speedo cable attached to the back of the generator, in the center of the back plate. Took me a bit to figure out what it was. The owner confirmed that it fed the tach.

 

I don't know much about this one. It came with this hollywood panel. I don't see a date on it, it has a brass case and internal light. It seems to work when you turn the cable. From what I've heard about cable driven tachs they are pretty accurate.

 

Just to clear things up a little, here's a pic with the sender attached to the tach...

 

Actually I already did. This is the back of the tach. with the second section removed. All I did was take a cheap plastic late model tach and use the guts in the old housing. I transfered the needle. I know it won't read accuratly but I don't care. I ain't racin'. I don't think I've had a working tach. since that Dixco I bought at the Pep Boys store in 1965.

My roadster came with a red football tach. but no sending unit.




my cable drive tach.




This is the type that uses a sender under the dizzy cap. You can see how deep it is with the added section. The sender has the wires with a female plug.

I hope that we all can learn from this post. I don't know what kind of racing in the late 40s that would need an 8000 RPM tach. Maybe Indy?

 

Yes, what you are showing is an ELECTRIC, not a mechanical like he said. He mentions "drive cable" often. Maybe I am confused by his terms.

 

I think he's referring to this...

 

S-W 9000 rpm tach.

 

deuce, i got that same tach laying in the shed.

 

This is why you should take notes when old guys talk...

A restorer friend that died about 5 years ago, long ago showed me and old tach that he got when he worked for Stewart Warner in Indiana the 40s and 50s, as a machinist. He explained what each thing was and why it was special and what they made tachs for... All the things that Ryan is curious about... Do you think I remember any of it?

Nope.

 

36C8 shows the tach I had.

I got it confused with a mechanical one we did on another car.

The install was done just over 50 years ago and it takes a bit of wading through the memory banks.

I think the key thing that impressed me was the connection to the top of the distributor shaft where the rotor originally went.

In any event, it was a great tach.
Looked good, worked well and not too many other cars with tachs running around town at that time.

Not sure where it got off to, like many other things I wish I had it today.

 

Thanks for the info, gents. If I'm not careful I might learn something.

Here's one of mine. Don't know how old it is, but it obviously came out of an Allard, and I know it was in a hot rod in 1950. I have most, but not all, the gauges out of this car.

 

That's a top-notch Stewart Warner set. hang on to em.

 

They're not in great shape, but I am planning to put them back in a roadster some day (the plan is to recreate the roadster in the photo... I have a bunch of parts from the original).

Any recommendations about rebuilding gauges? Or who can? I've had some people tell me to send them back to SW for refurbishing.

Anyone have any input?

 

Pretty sure United Speedometer still offers an instrument repair service.

 

Sent pm

 

My 1947 F. E. Zimmer and my 1950 Bell catalogs only list the Stewart Warner tachs like the Allard tach with the whole number printed on the dial...1000,2000 etc. up to 8000. They were sold for Fords. Cable driven off of the cranknut. Complete unit was 43.85 The tach head alone was only 20 bucks...(1950 bucks)

The 1952 Newhouse catalog lists an electric SW tach that looks just like the Sun football style and used a black box style sending unit similar to the Sun. Looking at the picture you'd swear it was an early Sun. The text says it's SW.

Certainly not a complete list but it shows what was being marketed to the hot rodder in that time period. The "winged" tachs don't show up in my hot rod catalogs until about 54. Others can probably give the dates of manufacture for the different styles.

 

I have a set of 1939 ford converted for racing by a company here in Los Angeles called Maring and Company. Speedo 180mph and 8000 tach. I posted them on the "what rare parts are you running" thread. I can't post them again for some reason....Lucky