I just purchased a '76 L-48 that has 45k miles.
The car is pretty much bone stock except for belts & hoses. One thing I noticed is the Tach reads backwards ???
Idling it is on 6000 or so and as I gas it , the needle goes back towards zero side...
any help for a newbie ?

 

Boy that's a new one, I don't have an answer but here's a bump for you. Welcome to the forum.

 

Yup... new one for me too!

What does the needle do when you turn the key on...without starting the car?

Willcox

 

installed on southern side of hemisphere?

 

Turn the key on and it goes over to 6500 , at idle it is around 6k and as I gas it moves over to 5,4,3, etc...

Thanks for the replys so far guy's !!
I know there is a wiring circuit board that runs the tach ? I just don't want to FRY Anything by swapping wires around...LOL

This is my first Corvette ....sold my '67 RS Camaro a few years back and got the bug to step up


Looks like you have a great Forums here ! thanks for the welcomes

Here is a link with a few pics of the car & Ad > http://cgi.ebay.com/ebaymotors/ws/eB...=STRK:MEWAX:IT

I think I made a good deal on it ??? I gave reserve price which was just slightly above the last bid

 

My tach does a similar thing. I had replaced the board and it worked fine for a while, then it started doing the backwards thing, only with the key on it sits at zero, hit the gas and it goes to 4000 backwards.
The other day it worked fine and then when I started it again, it went backwards.
I think there is some sort of wiring problem, maybe a ground or something???

BTW, you did get a good deal.

 

Your steering wheel looks like one I had in a Vega Kamback I owned and blew up as my first car ever....Dang aluminum heads.....
Anyway, I hope someone can help you, that would drive me nuts ! ....

 

CS..

Check the wires at the tach filter and make sure they are not coming loose. Bypass the filter and plug the tach straight up to the distributor. If this solves your problem you know what to replace.

Post your results.

If the tach is going to zero, it has power and ground. Now these could be loose somewhere so you might want to check them out too!

I've never tested for a tach going backwards but as soon as I get the new boards finished, I'll have some to try it out on. Maybe I can find out the cause.

Both of you.. If you want to send me the tach, I'd be happy to test it for you no charge. It only takes me 2 minutes to do this.

78-82 cars the tach is a breeze to remove... 75-77 you have a job ahead of you if you need to remove it.

You can test the wires at the connetor for power and ground if needed without removing the tach. Just reach under the dash and un-plug it. I have a picture on our site that shows which wire is the power, ground and signal wire.

If you test continuity on the signal wire from the tach connector to the tach filter connector you should be able to rule this wire out as the cause.

All that is required to operate the the tach is power, ground and signal.

On the OP's tach... We'll if the tach is not going to zero when you turn the key on, this is a problem. This to me indicates there is a board problem!

Willcox

 

Thanks Willcox !
One wire coming out of the distributor goes to what looks to be a Capacitor or something that is mounted at the top of the intake manifold @ driver side rear

Is this the filter you speak of ???

 

 

Thats the one !!!
I'm out of town working but will be home middle of next week and I will hook up direct and let you know what happens ??

Thanks Willcox again!!!

 

You're not kidding about a job to remove the tach from a 76.

Mine has not had a tach filter since I got it. I did put one on and nothing changed, same problem, so I took it off.

I tried get to the back of the tach from underneath, I don't see a way to do it unless I haven't found the right path. I'll keep at it, Rmorgan, let us know how you fare.

 

Stop driving the car in reverse! sorry I couldn't resist.

 

Willcox > can you reccommend a repair or tech manual you might sell that would help out a feller like me with alot of these problems ?

 

For starters, get the Assembly manual on CD. http://willcoxcorvette.com/advanced_...%20manual%20cd. Ships for free and has OCR text search function. So in this case you could type in the word "filter" and it would take you to the tach filter page.

I'm working on a manual for tach diagnostics right now, it's just not finished.

On our site there are over four hundred different repair and help suggestions pages, so take a look at them. Here are the pages that are related to your year car.
http://willcoxcorvette.com/advanced_...+%23&x=39&y=16

Next would be go pick up a good used copy of the original GM service manual.

Aside from that you should be able to find what you need.

Willcox Inc.

 

Hi, my 75 convertible does the same thing..I'll bypass the filter tommorow and report the results..
By the way, Wilcox, after reading and responding to these forums. I think I now know who to purchase my vette parts from...Thanks for all of your positive and useful ideas...

 

Thank you Gary, that's what we are here for!

Willcox