'70 ground location(s)?

[adam schorr]

I realize this is an extremely basic question:
I want to check the ground(s) on my '70 LT1.
How many gounding locations / straps are there?
Where are they located? At the starter? Exhaust?
A prominent guage & clock repair vendor suggested I check the ground connections for a good, clean ground, as a possible remedy for poor (too low) water temp guage reading.
I replaced the temp sending unit with correct pin-head style, and used one (1), and only one (1) time 'round of teflon tape seal.
I know, i know, it could be the tape! But, didn't the tape get cut by the grooves biting into the block upon install?
Before I re-do the sending unit WITHOUT the tape, I'd like to check the ground by making sure it's as good as possible?
The car starts. Everything else works.
Thanks!

[Jeff Broughton]

Re: '70 ground location(s)?

Adam, I'll be interested in seeing the responses to this question, as I have the same issue with my '69 small block. I replaced the sending unit with the "correct" one from Lectric Limited, with no tape. I have never seen my temp gauge go beyond the first notch on the gauge (160 maybe?), even in July 4th parades! I just find it hard to believe that the car never gets any hotter than that, although I guess it's possible. All of my other gauges appear to be accurate.

Jeff

[adam schorr]

Re: '70 ground location(s)?

Jeff,

You used no tape? Your experincee makes me think re-replacing mine, with no tape, will have no effect on low temp readout we both get.

Any leaks?

Maybe Lectric's units are suspect...

I know my car is runing at about 180 degrees. We shot upper radiator hose with laser temp gun.

[Joe L.]

Re: '70 ground location(s)?

adam-----

There are lots of grounding locations on a Corvette. Many of the grounds, including those found on the exhaust system at the center clamps, are primarily related to noise supression in the radio.

Other major grounds which are otherwise critical and functionally very important for your 1970 application are the following:

1) main ground located near right (passenger) side engine mount. This is a large diamter cable which electrically connects the block to the frame;

2) battery negative connection to the frame at the crossmember;

3) harness ground at the starter. This is a black wire from the harness with a ring terminal which connects to the outside starter bolt.

ALL of the above MUST be in good condition with clean, tight connections.

I do not recommend the application of ANY sealer, at all, to the temperature sender. So, remove your sender and thoroughly clean the threads BOTH on the sender and in the head. Then, reinstall the sender. I don't think that you'll have any leaks if you sufficiently tighten the sender (do not overtighten). The electrical contact "through the teflon tape" is NOT sufficient to properly ground the sender.

The above may or may not solve your problem. However, you "need to go there" to eliminate these things as a source of the problem you are having.

[Jeff Broughton]

Re: '70 ground location(s)?

Adam, I originally used tape on it, then saw that Lectric Limited recommends no tape so I removed it. I saw no difference in the reading. No leaks. An interesting side note on that subject though - I have aftermarket aluminum heads, which are both drilled for a sending unit. I bought a brass plug for the passenger side head, and DID have to put tape on it to keep it from leaking. Not sure what the difference was, but the sending unit doesn't leak at all without sealant on it.

I had the body off of mine over the winter and replaced all of the ground wires, so that's not my problem...

Jeff

[adam schorr]

Re: '70 ground location(s)?

Joe, Jeff,
Thanks for the input. It'll take some free weekend time to get cracking. I'll let you know what happens.