Sun Tachometer Retrospective

[ol_skool_chevy]

Originally Posted by 198plus

That is really nice....Almost like mine, except I'd rather have a vacuum gauge instead of the clock.

what is thats clock out of???

[jayoldschool]

Can anyone help identify this tach? Wondering if it needs a transmitter, and if not, if it will work with a 6cyl.

[pope]

Are the terminals marked with anything?
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[jayoldschool]

Don't have it yet. Those pics are it for now. I'm hoping the back is enough to identify it.

[markeb01]

That is a “two piece” tach that does require a transmitter. The later transistorized tach that doesn’t need a separate transmitter (FZ series) has a separate can bolted to the back of what you see in the photos. There should have been a data plate under the retaining clamp that identifies what type transmitter, cylinders, and voltage the tach is designed to serve. Hopefully the information may be painted on under the clamp.

This is what the data tag normally looks like:

[Snowbound]

Do the factory tachs require the sending unit? The one I have is from a '66 3 ton truck.

Thanks for any info,

Brian
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[markeb01]

Originally Posted by Snowbound

Do the factory tachs require the sending unit? The one I have is from a '66 3 ton truck.

Thanks for any info,

Brian
Posted via Mobile Device

If it's a Sun tach in a GMC it will require the transmitter box. They even show it in the ad literature:



The first Sun tach to not require the separate transmitter was the FZ series, and to the best of my knowledge these were never factory installed.

If it's a Chevy tach, hopefully someone with Chevy instrument experience will respond as I don't know what pieces they used. I would imagine they used Delco tachs (or some brand aligned with GM) and would likely be engineered to not require a transmitter.

[Snowbound]

Ya, mine is a Chevy cluster. I'll have to dig out the assembly manual and see if there is any info in there.
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[bgbchevy]

Originally Posted by markeb01

They will fit right into the dash of a GMC since Sun tachometers, Bat-O-Meters and Vacuum gauges were all available in the 3 3/8” size, and originally offered as factory accessories.

This is the accessory sun vacuum gauge referenced above. I bought this (not the one pictured) as a birthday gift for my Dad and his 66 GMC.

[jayoldschool]

Here's the auction for the pics that I posted (not mine!). Thought someone else might get a deal:

5000k Sun Tach on ebay

[sodly]

With the repro dash tachs where does a person set the red markers? What is the red line or power band for the various engines? Mine is a '66 with a 327 and TH400.

[padresag]

depends upon your power curve and modifications to your eng. if your 327 is a stock eng use the stock marker positions
ron

[sodly]

Yes, mine's all stock. What are the stock positions for a 327/TH400 setup? Thanks.

[LostMy65]

Jegs has it on special for $109.99 plus free shipping.
http://www.jegs.com/i/Sunpro/885/FZ8...FbCDQgodZykANw

[kieth]

Originally Posted by jayoldschool

Can anyone help identify this tach? Wondering if it needs a transmitter, and if not, if it will work with a 6cyl.

ORIGINAL DASH:
http://kieth.smugmug.com/Trucks/66-G...5848&k=FM9gWk5


I SENT MINE TO A GUY OVER IN HOT SPRINGS ARKANSAS AND HAD IT CONVERTED TO NEW ELECTRONICS, SINCE WE DID NOT HAVE THE EXTERNAL BOX. COST ABOUT $195.00 BUT IT WORKS GREAT AND LOOKS NICE IN THE GMC DASH......KIETH

AFTER REWORKING THE DASH AND INSTALLING A BATOMETER AND THE SUN TACH.....ALL ORIGINAL INSTRUMENTS.....

http://kieth.smugmug.com/Trucks/66-G...8658&k=X8WmmMg

[sodly]

Originally Posted by sodly

With the repro dash tachs where does a person set the red markers? What is the red line or power band for the various engines? Mine is a '66 with a 327 and TH400.

Never did find out what the "stock" positions are for the red needles. Anyone know?

[sodly]

Originally Posted by sodly

Never did find out what the "stock" positions are for the red needles. Anyone know?

I have a 66 C20 with a 327 and TH400. Anyone know where the red line arrows were set from the factory? Someone?

[markeb01]

Originally Posted by sodly

I have a 66 C20 with a 327 and TH400. Anyone know where the red line arrows were set from the factory? Someone?

I believe the lack of response indicates nobody knows the answer. I’m not even sure why there are two arrows. Perhaps one was for maximum torque and the other was for maximum rpm? Unless you can find a photo of an original tach in a sales brochure, my suggestion would be to look at a specifications table like the one attached and go with the torque and rpm limits.

For example – assuming you have a 4 barrel 275 HP 327, maximum torque would be obtained at 2800 rpm and max rpm would be 4800. And this table may not be accurate for trucks as I don’t believe many of these engines were offered yet in the standard passenger trucks.

http://www.carnut.com/specs/gen/chv66.html

[sodly]

Yeah, I've wondered the same thing about the 2 arrows. Thanks for the chart. Like you, I'm not sure if it applies to the trucks. I'm kinda shocked nobody here knows the answer. Very few questions are stumpers around here.

[rudyyloverboiii]

Originally Posted by ol_skool_chevy

what is thats clock out of???

I second that!

[Brim]

Going with the repo Sun Tach II on my 64 C10/283/TH350 with HEI. I know the green wire will connect on the - side (Brown Wire) of the distributor cap. But where should I connect my red (power) wire to? What about the ground (Black) and light (White) wires too? Is there a particular place to connect them too?

Thanks,
Mark

[jayoldschool]

Red: battery power (check fuse panel for BATT terminal)
Black: chassis ground (any metal)
White: dash illumination (off headlight switch)

[andyh1956]

Originally Posted by sodly

Yeah, I've wondered the same thing about the 2 arrows. Thanks for the chart. Like you, I'm not sure if it applies to the trucks. I'm kinda shocked nobody here knows the answer. Very few questions are stumpers around here.

I was told a long time ago the 1st arrow was set to an engine rpm while at the light, while the second was shift rpm. Set the 1st arrow just below the stall speed of your converter, supposed to help with all the different things you have to watch after coming outta the bleach box & get staged. Manual trans guys usually didn't pay much attention to the 1st, or sometimes even the second indicator. Can't confirm this, only that I asked the same questions 45 yrs ago & that's what I was told. My tach didn't even have adjustable indicators!
Gotta remember this was the era "Before" stutter boxes! People were still running Mallory & Sanderson Mags back then!

[Keith Seymore]

Originally Posted by Keith Seymore

Here's one for ya:





That Tach has been sitting there for 45 years -

K

Originally Posted by Keith Seymore

You might appreciate this little tidbit:

My car still uses the old battery powered sending unit, mounted underhood -





When I got the car running again back in the mid 90's, naturally the batteries were dead and the tach didn't work. I thought "...where am I going to get those old batteries like that?"





Well, I noticed that they were physically about the same size as a modern "AA" size battery, although the modern battery is 1.5V and these vintage batteries were 1.35V.



I asked one of the electrical engineers at work about it and he said "...I'd just put a couple AAs in a flashlight and run 'em down until they're 1.35V".

That's what I did and it's been working fine ever since.

K

My tach finally quit working.

This might not be germaine but I started it back when the weather was cold to let the car run some and the tach went to about 1/2 of what it should be reading.

I replaced the batteries today as described above and that didn't do it.

I'm going to make sure the "new" batteries are not dead and after that I'm out of ideas.

Any suggestions?

Thanks in advance -

K

[jayoldschool]

Try cheap rechargeable AAs. They are 1.2V...