Technical Tach set up for crab distrubutor

After one year, my 32 roadster is on the road as a basically stock 32 hiboy with a hopped up 37 flathead motor and a 39 trans. The motor has a 42 - 46 crab distributor. I am looking for advice or leads to any suppliers regarding obtaining a tachometer setup. Thanks in advance. Steve

 

Welcome to H.A.M.B.
Best answer is to do a search on here with the magnifying glass icon in the above tool bar. I prefer hitting the "more " button at the bottom of the box when doing searches.
You can go with a vintage Sun tach and transmitter, upgrade to the new battery style. This is a wired unit.
The other option is the Stewart Warner crank mounted 90 degree Drive Joint with a cable and mechanical tach.

There are other options, but I like these.
Look under the classifieds here and Ebay, There's the Ford Barn also.

 

If it is converted to 12v negative ground then there are many electric ones available. My 37 Buick straight eight just takes one wire to the minus side of the coil and has worked for at least fifteen years.

 

Are you looking for a mechanical tach or electric? Any electric tach will work with that setup.

 

Thanks, guys.

I would prefer electric, but I am running 6 volt positive ground, so that must limit my options.
I will check into Sun, Stewart Warner and Westach and any others for their products.

My preference is for vintage (or vintage look) gauges where possible.
A complete mechanical setup that works sounds hard to find (and expensive if I do find one).

Who knows? Some H.A.M.B.er may offer up something from their collection.
In the meantime, I will keep searching the H.A.M.B., Ford Barn, Ebay, etc...

Future suggestions or leads are appreciated...
Steve

 

Isn't @tubman doing something for 6v positive ground tachs? I might be confused about it though.

 

Budget36: I contacted him and yes, he developed and sells an electronic device that converts 6 volt positive ground of the car to 12 volt negative ground to operate a modern tach. Thanks for the good lead. Steve

 

I bought an old RAC tach from the local scrapyard that was in fair shape. The needle moved freely and the glass was clear. I sent it somewhere and they replaced all the electronics so it would work with my 6V pos ground setup. I’ll get you the name of the place if you’re interested.


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Jeff34, I am interested, depending on the pics and the price. Thanks for the lead. Steve

 

The place "Jeff34" is referring to is probably "Williamson's Instruments". Here's a link : https://williamsons.com/. Don't let the picture of the fancy classic car scare you off.

"Steveareno", a couple of years ago, we converted an old "Sun" control box to run on 6 volts positive ground and drive it's matching tachometer head just to see if we could do it. It worked great, but I am not using it. I would sell that setup for $500.00.

 

Yes, Williamsons. That’s the place. I sent them two RAC’s. One had a metal housing, the other plastic. I had them rebuild the metal housed tach. I’ll post the cost and a pic tomorrow.


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Here’s my RAC.


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Jeff34: Thanks for the pics. What was the cost?

 

I'm checking with Williamson's. Thanks to all.

 

personally, I like the Airguide model 656 tachs. Since you are sending to Williamson, find one you like and have it converted to the system you planning on running. This one is only 45 Buy it now

https://www.ebay.com/itm/AIRGUIDE-T...477491&hash=item3f9fe82e40:g:XkAAAOSwCXJbGEQb

 

I think it was $100.


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I hate to contradict another member, but I would advise "Steveareno" that he get a firm cost and time commitment from the vendor before he proceeds. One of the reasons we developed our "Tach Driver" is the cost of these types of conversions. They are more typically in excess of $300.

 

I appreciate all the information, guys. Decisions, decisions...

 

Tubman, how does your tach drive work? What are the limitation?

 

It is an electronic device about the size of a pack of cigarettes that allows any 12 volt negative ground "motor-type" tach to be run a on a 6 volt positive ground vehicle. The wiring is very simple. There are three terminals on one side and four on the other. The three terminal side is for the 6 volt connections. One for power (negative 6 volts), a second for signal from the coil, and a third for ground. The other side is the twelve volt side. One for tach power, one for the tachometer light, a third for signal to the tach, and a fourth for ground. If you look, just about any tachometer out there these days has four wires for input. They are red for tach power, white for light power, green for tachometer signal. and black for ground. Those four wires go into the sockets on the 12 volt side.

To hook it up, you need to run a 6 volt power lead from the ignition, a ground to any place appropriate, and run a (usually green) wire from the coil. Then hook up the twelve volt tach to the other side. Here is a short video of the unit running on my '51 Mercury engine on my test stand. The device is the black box shown right before the end of the video : .

So far, we have not seen any limitations. It has successfully driven every "motor-type" tachometer we have used on it, from $10 "swap meet specials" to $600 Autometers with memory and playback. Unlike the old "meter-type" tachometers (Suns, Stewart Warners, etc.) that use external controller boxes, just about every self-contained tachometer built in the last 40 years is a "motor-type" and will run with our unit.

From what I see from the picture of the Airguide tachometer in your previous post, it has the four input wires typical of a 12 volt "motor-type", and as such, should work with my Tach Driver.