Could someone tell me why my speedo cable is making a clicking noise on my 74 Vette. The faster I go the faster the noise. Seems to be a burning smell from it also. Any ideas?

 Could just simply need to be lubricated. Does the needle "jump" as you drive?

Yes it does. Mostly at low speeds around 10 -20. when it jumps the needle jumps the same time it clicks

I would suggest removing the inner cable and lubricating it....that should take care of the problem. If it does not, then the speedo head itself is likely dirty, or otherwise damaged.
The inner cable can be removed by dis-connecting the cable from the speedo head, under the dash. It's kinda hard to get to, but it can be done. I find it easier to get to by removing the upper dash pad, and going in from the top. If you have TINY hands, you can get it from underneath. Once disconnected, pull the inner cable out of the outer cable housing. You can use engine oil, trans fluid, or a light weight lithium grease to lube the inner cable...just make sure to lube the entire length. Then, slide the inner cable back down into the outer housing, spinning it a little as you go. Re-attach the cable to the speedo head, and see how that works.
There is a funky clip that holds the cable to the speedo head, that is sometimes frustrating to get to, to release the cable. I have a pic of it somewhere, to give you an idea of what it looks like...I'll have to look for the pic, unless someone else(Bob?) has one handy.




|UPDATED|9/15/2014 10:25:35 AM (AZT)|/UPDATED|

I pulled my cable out on my 78 and help my friend on his 81 this year. I had 2 sections with rust build up. I knocked that off with a wire brush, greased the heck of it and reinstalled. No issues since. It reall was not very are to disconnet on either end. I dod however, take precautions not to get any grease on my interior. I used a cheap plastic paint drop cloth. Pretty straightforward fix. Enjoy! 

I have cruise control, so to relube the lower cable is fairly easy.

No...the top end of the cables have a squared off drive fitting swedged on them that is larger than the ID of the outer cable housing. The inner cable will only come out from the top.