How old is this sun tach & other questions

I bought this sun tach yesterday. I think I over paid at $90.00, but I thought it was wicked so I bought it. The actual face is 3" it's the green line and maxes out at 7k. The box is 12V 8cyl. Everything looks to be in good shape, I just need to test it. My questions are-How old is this thing? How do I hook it up to a HEI set up? Did I over pay?

 

I have one that seems to be just like it. My dad let me use it in my 55 Chevy truck way back when I started driving. He thinks he bought it in 1968 or 69 to put in his 58 Chevy, then later in is 70 Nova. I'll try to remember to take a picture and post it for you so you can compare. Mine doesn't have a box tho, just hard-wired to my HEI.

 

I believe mine is a SUPER-Tach tho with a blue line instead of green.

 

I believe the EB-9A has been around since the early-mid 60s.

If yours hasn't been converted, it will need to either have the box electronics updated, or you'll have to just drive around with an innaccurate tach.

Inside the black box are (or should be) 2 aa batteries.

The way the tach processes the signal from the distributor requires the aa batteries be present, but when the tach was engineered, mercury cell batteries were common.

Mercury cell batteries have a "clock cycle" to them, or an electrical pulse. Modern alkaline or li batteries don't have the same pulse, and throw off the accuracy of the tach. It's been a while since I've looked into how far off it gets, but it's not linear, if I recall correctly (meaning as you rev, it gets less accurate...which is where you need accuracy).

There's a few places that can replace the electronics in the box with a properly timed IC (I used tachman, do a google search for him).

Some people put a later GM tach module in the box, and there are instructions for how to do that online, but from what I've researched it's not as reliable or accurate as having a purpose designed circut (the tachman circut is designed for the sun tach, whereas the GM module is designed for a GM tach head).

Anyhow, that appears to be a module and tach that are in really great shape!

Open up the module and see if it still has batteries inside it (and if so, you might want to check for corrosion, as the old batteries sometimes leaked all over the inside of the module).

 

I keep finding info on the Super-Tach. Apparently the super tach was first introduced in 1965. So maybe this is pre 65?

 

Found the website for EB-9A restoration/conversion:

http://www.tachman.com/sun.htm

These guys took a module that I bought off of that auction site, and made it look and work like brand new!

 

You'd be correct there.

I'm having a hard time finding the exact time frame.

I am fairly certain the same module was used in early 60s chevys with the tach option. I know that 62 impalas had them, so the EB-9A is at least from 62, again, maybe earlier.

 

I just opened the box. The batteries were gone and everything inside looks really clean.

 

One key difference in the old mercury batteries, and modern AA is that mercury batteries are ~1.35 volts and modern AA are 1.5.

It's possible to drain modern AA down to 1.35 volts and they will then supply correct current, but still have the incorrect clock cycle.

There are some vintage camera suppliers that sell a "mercury cell replacement battery", that is supposed to do a good job mimicing the old mercury cell, but I'm still not sure if they would be proper in a tach.

If you don't care too much about accuracy, then modern batteries can be OK.

I'm trying to remember tach signal terminology...but am drawing blanks. Something about hall effect...

 

I read an article about draining some 1.5V batteries to 1.35V and using them. I do care about accuracy. I hate inaccurate gauges.

 

Big Eds Speed shop 1963 catalog.

 

Sometimes there is a date code inside the tach.

 

If you're electronically inclined you can convert the box over.

 

Do a search on sun tachs on here,there are several threads on these tachs. Some have used the the modern aa battery to their liking, some think its a waste of time. There was also a thread about building your own timing circuit. I myself am planning on building a 1.35 volt power supply and using that for mine. I'm not all that worried about accuracy as I'm not planning on revving my engine that high.

 

Appreciate the post Tommy. Good stuff!

 

So the 9K is new for 63. Would the 7K also be new for 63?

 

I think they went solid state in about 66 or 68 so it is at least that old and you didn't get hurt.

You may have to find batteries for that sender but I think you can get them on line now.

 

I hooked up the positive and negative leads on the tach to a 1.5V battery and it swept nicely. Now, if I get the correct batteries, or slightly discharged 1.5V batteries, and hooked it up to the HEI is that going to turn the tach and box into crispy critters?

 

I think the wide sweep was new for 63. As said above the factory 62 Chevrolet tach was the chrome small window type in the other scan. Both were taken from the same catalog. so they were both available at the same time. I don't believe that the first wide sweep Sun tach had any color stripes on the dial. This is a B&W photo but only one stripe. Later there was a blue and a green along with the white stripe but I don't know their years.

 

I do believe you can only run points with that transmitter (unless modified).

 

This is really interesting stuff. So from what I'm extrapolating here this tachometer is post 63 (Due to the green stripe), pre Super Sun tach (which was introduced in 1965). Was it 1 year only? Or did they continue making and selling it along with the Super Tach?

 

I am leaning in that direction for this car, but I would still like to know exactly what I have here in case I decide to keep it for a later, period correct, car or sell it, and have an accurate description and knowledge I can impart to a potential buyer.

 

I got a question for you...are you actually racing this thing where an accurate tach is important or are you, like me, just using it for period decoration? I have a super Super sun I believe for my 56 just for decoration. It has the color stripe I'd much rather have a Dixco because the were cheap and all the Mighty Mo jockeys ran them on their street drivers. The real race car drivers paid the extra bucks for a Sun that required the extra cost sending units.

correction I went outside and looked...
I lied. I have a Dixco but it is a blue stripe which makes it a newer model to copy the Suns. My favorite Dixco tachs had no colors and were just black and white.

 

If I use it it will be on the street. I bought it because I love the way it looks, it doesn't have branding all over it, it's big, heavy, bright and it says Sun electrical co. Chicago IL written just under the bezel in the old style writing. Honestly it looks like it came out of a time capsule. But....I hate points ignitions, and after my last go around with them I swore em off forever in favor of electronic. So I'm kind of at an crossroad, spend a few hundred bucks more to convert it to work with an electronic ignition? Or sell it and buy a later model one? So the more info/feedback I get from this wonderful website the better.

 

What is it going in?

 

My favorite not because it's any better....It is what we ran on the street.

 

It might be going on a 53 Chevy.

 

FWIW, I had this Sun RC-50 "Football" tach and EB-1 Transmitter converted to solid state by Williamson's Instruments (http://www.williamsons.com/). I think it's probably from the mid 50's-early 60's.

 

Modern Rechargeable batteries are 1.2 Volts, I don't know about clock cycle but I think it would be better to run rechargeables than drained batteries.
Just a thought.

 

Hey,
Just had been down the same road as you. I op'ed to go the route of going to one of suns repop retro blueline tachs because of the headaches. First it looks the part and it is dead accurate because it has new style electrics!

Here is a link to mine installed.
http://www.jalopyjournal.com/forum/album.php?albumid=30157&pictureid=343327

If you do decide to hook up the old one borrow a timing light with a digital RPM readout just to make sure the tach is correct! I ran into this once where I had an old sun tach thsat read 4500 at 5800! Glad I checked if you know what I mean.

Couple years ago before they repoped the sun tachs there was a guy stuffing modern electrics into old tach housings. Can't remember his name??? Someone might chime in with a name.