Any recommendations on fixing these problems?
Tach just doesn't work.
Speedo wanders around, usually shows much higher speed than actual?.

Haven't seen a reply, so will try to help....

I take it this tach is factory, and is in your '70 Elky?? Afraid I can't help on that, unfortunately; haven't any experience with the 2nd gens although I'd love to own one.

As for the "high-reading" speedo that jumps around.... I'm gonna assume that it didn't used to read high... or that you just got the Elky, and the speedo's been jumping around ever since. I'm also gonna assume you do NOT have cruise control; if you do, that's another possible source of the problem that I'll go into after you reply.

The jumping-around-and-reading-high is very often a sign of the speedo cable catching inside the sheath. What it does is get caught, then when it suddenly frees up, the inner core wire "jumps" ahead real fast like a spring that's been released, and causes the speedo to jump up and read high. If you don't do something bout it soon, something may break, usually the inner core. In an extreme case, the core wire catches and can also cause the speedo gear inside the tranny to strip, either the teeth or, usually, by splitting the end into which the inner core wire fits. This can make it EXTREMELY difficult to pull the inner core wire out of the split plastic speedo gear.

Cleaning and lubing the inner core wire may help although better would be to replace the inner core itself. Before you buy one, though, you should have a very good look at your existing outer sheath and make certain it's not crimped, or hasn't lain against an exhaust pipe and the plastic melted. If that's happened, you'd be better off replacing the whole cable. But if the outer sheath looks fine with no obvious sharp creases or bends, try replacing the inner core first.

And BEFORE you buy what's sposed to be a "drop-in", measure your existing cable as well as you can. This also applies to replacing the whole cable assy.

Ummm... I just hadda looksee at http://www.rockauto.com and the most expensive speedo cable they list is only $11.09 :D So you may just wanna replace the whole thing right off the bat. To find the speedo cable in their listings, go to that URL, click on Chevrolet, then your year, then your model, choose your engine, and THEN the kicker: click on "Body-Interior", which is where the speedo cable will be listed 8) You may also find the cable available from your Friendly Local Auto Parts Store (FLAPS) but beware of the universal kits, where you have to cut the cable to length and then use a special little tool that comes with the kit to create the square end on the inner core. While those kits work, they're not as much fun as installing the RIGHT one, already precut to length and ready to just drop in :D

If you replace the cable and the speedo STILL jumps around, the remaining possibilties are the gear in the tranny is wearing out. To replace the gear, simply unscrew the speedo cable from the tranny, then remove that 3/8" bolt that holds the speedo gear "adapter" into the housing. Pull out the housing (it may be stuck in there after being in place for years; just use a screwdriver in the notch to pry it out; DO NOT mess up the threads on the adapter, because the adapter may no longer be available!). The speedo gear is mounted on the end of the adapter: just pull it out. To replace it, you MUST count the number of teeth. They are also sometimes color-coded but it's best to also know the number of teeth. You then need to go to either a speedo shop or tranny shop to get a replacement (although you can TRY going to your local dealer but don't count on them having any stock any longer).

If THAT doesn't work, then either your cable is bent too sharply and is crimping the inner core, or the speedo itself needs replacement/rebuilding. There's places that rebuild speedos, some on the web, and many advertise in Hemming's various rags. I don't have any suggestions in this regard, sorry :(

Thanks for the info. Yes this is for my 1970 which I just recently bought. No cruise and it's a TH400, so it may be a lot newer.
I will have a look at the cable and remedy the situation, then post my findings.

How do you get the speedo cable out from the dash? I couldn't even get close to it today. :mad:

Somebody else will have to answer that, I'm fairly ignorant on the '68-'78 models :-(

How do you get the speedo cable out from the dash? I couldn't even get close to it today. :mad:

I had to change my speedo head when I got mine. Have to take the dash top off, lower the steering column and if I remember there are at least 6 or 8 bolts in the dash you have to take out. then you can slowly pry the dash to you then pull the speedo cable out.

68 to 72 was not much difference in dash configurations. One was for the SS the other for sweep style. Hope ths helps and if I'm wrong on this somebody please correct me.

Brian

Thanks, sounds like replacing the speedo cable is a REAL FUN JOB! 8O
Any advice on the tach situation?

Thanks, sounds like replacing the speedo cable is a REAL FUN JOB! 8O
Any advice on the tach situation?

Is tach original or aftermarket? I have hei setup on mine that says tach on distributor cap, just plug the tach wire in there.

Brian

Tach is original and the distributor cap has the tach wire plug in location. So should I try to find the tach wire and run it to the cap, or is the original tach wired diferently?

Try an find tach wire then hook up to the cap. I don't see why it would not work. Unless tach wire might be broke? Is there a wire hooked up to the cap now?

Brian

Thanks Brian,
I have to go out of town for about 3 weeks. I will post my findings on the tach problem when I get back.
Georges