65 corvette temperature sending unit

[John S.]

I have a ACR-12V-3 temperature sending unit part number 25037345 which was on a GM box. I am restoring a 65 Corvette 327-365 HP. Will this sending unit be the right one? If not what number is the correct one with the AC logo?

[Jack H.]

Re: 65 corvette temperature sending unit

The correct original part is an AC 1513321. Expect to encounter FOUR variations of the part dealing with how it's embossed on the neck band below the hex facets.

Some are stamped "AC Made In USA...." with the font upright to the main axis of the part while others are stamped inverted (upside down).

Then, some are stamped "12 Volt" while others read "12V". That results in four primary stamping variations and there are others (exact size of font plus prefix/suffix characters surrounding the main stamp).

The exact size of the stamped font + prefix/suffix characters are NOT addressed by the various NCRS Judging Guide books. However, some books DO lay claim to factory original/correct font orientation (upright or inverted) and to the part's voltage designation (12 Volt vs. 12V).

Bottom line, what's 'correct' for a given model year car varies with the specific descriptive text used. I've seen all four variations extracted from scrap yard donor vehicles over the years and I DID NOT see a correlation between the temp sender's stamped legtend versus the year of the car it came out of. My hunch is there was more than ONE set of production tooling that created the differences we see...

But, trying to sell that to some senior NCRS judges who are SURE they know the facts, is like swimming upstream!

[Jim D.]

Re: 65 corvette temperature sending unit

John, Here's a pic. of the one on my 65. It is the original that the car was built with and has never been removed.

[John D.]

Re: 65 corvette temperature sending unit

Jack, I have often thought the same thing as I have been removing junker AC TSU' from Fi units for many years.
For example some think that that a 63 used only one configuration of a TSU and we know it just isn't true.
One thing I have learned is never to use the word ALL in a particular item or part. The word typical or not typical is a better way to think.
It is typical for 63 TSU to have the letter upside down-to have 2 or 3 dots after&before the AC Made in USA but other AC TSU's were used also.

[Joe L.]

Re: 65 corvette temperature sending unit

I have a ACR-12V-3 temperature sending unit part number 25037345 which was on a GM box. I am restoring a 65 Corvette 327-365 HP. Will this sending unit be the right one? If not what number is the correct one with the AC logo?

John------


Although it may APPEAR of the correct configuration, GM #25037345 is NOT a correct temperature sender for your application. While this temp sender does have many applications, a 1965 Corvette is not one of them. Now, if you had a 1980 Corvette with 305 cid engine (California only), you'd have a part you could use. But, not for a 1965 Corvette (or, any Corvette except the 1980 305).

GM/AC Delco does have a replacement sender available for your application, GM #12334869, but there have been many REPORTED problems with calibration of this sender when used with original gauges.

[Gene M.]

Re: 65 corvette temperature sending unit

Does anyone have a chart that shows the ohm meter readings for the temp unit for mid year applications. I assume there is different readings as temperature goes up.

As I recall the p/n is not on the units (would be to small for me to read anyway).

[Joe R.]

Re: 65 corvette temperature sending unit

Does anyone have a chart that shows the ohm meter readings for the temp unit for mid year applications. I assume there is different readings as temperature goes up.

Gene,

Try this page:

http://www.lbfun.com/Corvette/Tech/vettetech.html

Click on "Gauges and Instruments".

Then click "Temp Sending Unit Info". I don't know how accurate the info is, but it sure looks like it may be a good start.

Joe