Sun Tach for my 57

[Bruce B.]

I just picked up an almost new Sun tach and sender for my 57 Corvette.
The only problem is finding the batteries. It takes 2 1.35 volt batteries specified as Mallory RM12R or Sun 1766-6. They are no longer available.
I have heard that AA 1.5 volt alkaline batteries will work.
Does anyone have any experience using the AA or is there a substitute?
Thanks.

[Jim L.]

Re: Sun Tach for my 57

Bruce,

It's my impression that the 1.35 Volt cells are used as references against which the signal from the sending unit is compared. As such, and assuming I'm right, changing to a cell of a different Voltage will affect calibration.

If that tach were mine, I'd assemble a small collection of Radio Shack parts to make an electronic voltage reference that replaced the original 1.35 V cells.

Jim

[Willard M.]

Re: Sun Tach for my 57

You might try Williamsons in Arkansas. They rebuild and service these old Sun units. I think that they did the one in my 62 409. They usually advertise in Hemmings.

[Clem Z.]

Re: Sun Tach for my 57

try a pair of rechargeable metal nickle hydride as they are 1.2 volts. those 1.35 were mercury cells so i bet they are long gone

[Steven B.]

Re: Sun Tach for my 57

Bruce, from D&M Restorations website:

D & M Restoration can rebuild and repair almost any antique, classic or vintage car tachometer to its stock/ original condition, or we can convert a mechanical tachometer to an electric tachometer while keeping the original appearance. We have designed our own circuit boards for upgrading and repairing many of the electric tachometers. For example, we can convert a standard Faria tachometer into a Rotunda or upgrade a Stewart Warner or Sun two-piece tachometer using our circuitry, therefore eliminating the need for batteries. Your tachometer is a vital instrument in the appearance of your car. With our restoration process, your tachometer will not only look original, but will operate like new.


Bruce, I am thinking of converting my old Sun fo rthe '57, also. let me know how you do yours and how it works. 'Got snow yet??

Steve

[Jack H.]

Re: Sun Tach for my 57

If that's true (batteries are a placebo reference representing the car's own battery), then the exact voltage level isn't important. Remember, when the engine is running, the charging system is active and battery voltage will vary in the 13.2-15 VDC range depending on the charging system's voltage regulator setting, the specific output level of the generator/alternator and the current charge state of the battery...

[Jim L.]

Re: Sun Tach for my 57

If that's true (batteries are a placebo reference representing the car's own battery), then the exact voltage level isn't important.

Jack,

I believe the exact Voltage is important as a stable reference. I'm aware of one other owner of a Sun tach in which a modern, readily available cell has been installed. The tach works, but it's calibration is poor.

Jim

[David S.]

Re: Sun Tach for my 57

You might try Williamsons in Arkansas. They rebuild and service these old Sun units. I think that they did the one in my 62 409. They usually advertise in Hemmings.

I agree.

I have quite a few Sun and Dixco Tachs. Williamsons does great work and are very knowledgeable. Give them a call.

-Dave

[Steven B.]

Re: Sun Tach for my 57

Bruce, Williamson's site;

www.williamsons.com


Steve

[Bruce B.]

Re: Sun Tach for my 57

Steve,
I found that the recharageable batteries in my wifes digital camera are 1.25 volts. They are the closest I have found to the original 1.35 volt Sun batteries.
Hopefully I will try them out and I will post info when I do.
The Williamson Instruments web site is interesting. They get around $180 to $200 to do a conversion to electronic on the Sun tach.

No snow in So. Ohio.
Tonight is actually our first hard frost. The weather has been great and the Corvettes are being driven until snow falls.

Do you have any experience with converting Hilborn stack injection to electronic injection?
I have heard about a few people who can do it but still don't feel confident about it. I would love to put that kind of setup on a Corvette with the stacks coming through the hood. I have an extra 57 hood which was once cut so it's ready to go.
Bruce B

[Clem Z.]

Re: Sun Tach for my 57

Steve,
I found that the recharageable batteries in my wifes digital camera are 1.25 volts. They are the closest I have found to the original 1.35 volt Sun batteries.
Hopefully I will try them out and I will post info when I do.
The Williamson Instruments web site is interesting. They get around $180 to $200 to do a conversion to electronic on the Sun tach.

No snow in So. Ohio.
Tonight is actually our first hard frost. The weather has been great and the Corvettes are being driven until snow falls.

Do you have any experience with converting Hilborn stack injection to electronic injection?
I have heard about a few people who can do it but still don't feel confident about it. I would love to put that kind of setup on a Corvette with the stacks coming through the hood. I have an extra 57 hood which was once cut so it's ready to go.
Bruce B

i built several BBC that use gasoline hilborn mechanical FI on the street. the mileage was not too good but they ran well.

[Steven B.]

Re: Sun Tach for my 57

Bruce, hopefully the camera batteries work. I had some exposure to Hilborns on a 327 Corvette in '65-'66 but it was not streetable---but went like stink.

Some info. from Hilborn on their EFI conversions;

Steve


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[Clem Z.]

Re: Sun Tach for my 57

the engines i built were for a sprint car team owner who owned a sprint car team that brad doty drove for before he was hurt so they a lot of experience with hilborn injection.