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-   -   90ohm <-> 30ohm (https://67-72chevytrucks.com/vboard/showthread.php?t=833623)

65C10ED 04-20-2022 10:20 AM

90ohm <-> 30ohm
 
I installed a '69 Camaro tank under my '65 and find the sending unit is not working correctly with my stock '65 fuel gauge. From what I have discovered, the '69 sending unit is 90ohm, while the '65 fuel gauge is 30ohm, thus the incorrect reading. My question is, if I purchase a new fuel tank sending unit for a stock '65 in-the-cab tank, would it be possible to swap the 30ohm resistor of the '65 sender with the 90ohm resister of the '69 sender in order to make the '69 sender work correctly with the stock '65 gauge? Has anyone done this?

The Rocknrod 04-20-2022 12:24 PM

Re: 90ohm <-> 30ohm
 
A couple of suggestions in this one thread - http://67-72chevytrucks.com/vboard/s...d.php?t=600116
If the tank is 6 inches deep you can use this - https://www.summitracing.com/parts/tnk-t-gme-06
Or 5 inches deep - https://www.summitracing.com/parts/tnk-t-gme-05

65C10ED 05-12-2022 03:23 PM

Re: 90ohm <-> 30ohm
 
1 Attachment(s)
Update to my queston: Along with my 69 Camaro sender that came with the new gas tank, I also had a sending unit from the 59-60 Impala tank I had attempted to use prior to the Camaro tank. The sending unit from the Impala had basically the identical parts the Camaro sending unit had except for the shape of the pickup tube and the resistor/rheostat was 30 ohm. So, I figured I could take the resistor/rheostat out of the Impala sender and install it in the Camaro unit. It worked! I changed my 90 ohm Camaro sender from 90 ohm to 30 ohm and it was pretty easy. See the attached photo.... 1. The "can" that holds the resistor is held together with just 3 metal tabs. I just folded them open and the can opened up. There's one loose spring inside that goes on the end of the float shaft. 2. Inside the yellow container is the resistor/rheostat that is an arched strip of metal with very fine wiring wrapped around it. It's the same kind of thing that is inside slot car controllers and it's attached to the container by only one brass rivet that holds the resistor/rheostat as well as attaches the power wire. I carefully drilled out the rivet from the outside....removed just enough to remove the rivet. 3. Then I was able to remove the rivet and the resistor/rheostat. To reassemble the Camaro sender I installed the 30 ohm Impala resistor/rheostat in place of the Camaro one and then hammered the old rivet back in where it was originally. Because when I drilled it out the rivet was shorter, I ground down the block the rivet goes through just enough to give me more rivet on the end to hammer down. Before hammering down the rivet, the power wire has to be included inside the rivet. Once I got the rivet as tight as it was originally I was able to reassemble the can and fold back the tabs. I noticed that the rivet needs to partially cover some of the fine wiring around the resistor/rheostat to be sure there is a connection and I had to move some of the fine wiring to put it in correct position. 4. But care must be taken with the fine wires.... they seem pretty fragile. So after I reassembled the sender, I connected it up to my 65 gauge and it worked! As I raised and lowered the float arm, the gauge responded.

SOON2BLAZE 05-14-2022 02:55 AM

Re: 90ohm <-> 30ohm
 
Good write up. Using the same 69 tank on my 66. I was going to get a NOS GM gas gauge from a 70-80's from ebay and pilfer the 90 ohm resistor off the back of the gauge and added it to the 66 gas gauge.
Dophin also makes a ohm converter
https://www.ebay.com/itm/26550897351...cAAOSwVbph7t4D

The Rocknrod 05-14-2022 09:43 AM

Re: 90ohm <-> 30ohm
 
Pretty cool.


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