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Premium Member
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188 Posts
Discussion Starter #1
Where can I find a chart with the coolant temperature sensor resistance values for a 65 SS with gauges?
Not the newer electronic computerized values that are easy to find on the internet.
Thank you!
 

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Premium Member
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188 Posts
Discussion Starter #3
Thanks for your response Mike!
I had searched and searched the internet for a couple of days, and only came up with the same chart and graphs that you posted. And I don't ever remember actually seeing a chart in the many Motor's manuals I poured over in my younger years.

The 1st graph shows the comparison of the newer computer controlled (OHMS)) signal (TOP LINE), and the older (OHMS) value on the lower line which would apply to the 60's and early 70's cars.
The 2nd graph is the older (OHMS) value with the acceptable range of error.
The 3rd chart is the computer controlled values.

The graphs do not show a definite value as exacting as the computer controlled bottom chart, and are difficult to pinpoint the exact measurement of OHMS.

I have recently swapped the engine in my 65 back to an original 65, ZB 327, to replace the factory ZB that was popped around 1971.
When I bought the car 14 years ago, it had a non-Nova 327 in it. I had a 66 ZA engine kicking around for over 30 years, and decided to do that one up for the car.
.030 over, 11:1, balanced and blueprinted, Comp Cams 69 Z28 solid, 700 Holley, headers, 69 Z28 intake, and a new temperature sending unit from C2only.
After advertising for many years and procuring the correct 65 ZB block, I had that one done exactly like the 66 ZA and swapped them out. I also installed a new temperature sending unit identical to the one in the old engine

The new engine is broken in and runs like a champ, however, I have observed that it heats up faster. And now that it is getting into the warmer weather, it is running at about 3/4's on the temperature gauge on an 85* day, whereas the engine I took out never ran hot.

I still have the 66 ZA engine sitting there and decided to compare the sending unit values between the 2 engines.
Both at 75*F, I am getting about a 250 OHM discrepancy (750 + 500 OHMS) between the sensors, and am using an IR thermometer held about 8" from the aluminum manifolds, aimed at the base of the sensors. Also, both brass sensor bases read "0" OHMS to an intake bolt, indicating a good ground.

When the temperature gauge reads @ 3/4, the IR thermometer aimed into the radiator and at the manifold where the gooseneck bolts on both read 180*F.
Both the IR thermometer and my meter are Flukes, and the thermostat is a 160*F, which is working properly.

I even plugged the water pump by-pass thinking that it was short circuiting too much coolant and not sending it to the radiator. This made no difference at all.

I am pretty much convinced that I don't have an over-heating issue, just a problem with sensor accuracy.

I guess we can't expect quality from off-shore temperature sensors (as with many re-popped parts)!

My search continues for that chart...

Thanks Mike!
 
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