TACH reading 3 times higher

[Dano69c10]

The tach on my '79 c30 454 is reading 2100 at idle and maxes out when I'm driving around. I thought this only hooked up to the HEI distributor. The wire looks fine, any help on this? Are there any other wires to look at?
Thanx in advance
Dano

[82c10]

check the ground, make sure it is grounded good , we undid the screw that held my ground on and the tach maxed out.

[ocbaud]

what kinda tach is it? if its an aftermarket tach it possibly could have a setting for 4, 6, and 8 cylinders. it its set to a lower setting, it will do what you're saying.

but being as you have a c30, i'm guessing it has a stock tach in it?

[Dano69c10]

Stock TACH, where's the ground?
Dano

[ocbaud]

i'm not sure about the ground problem or if its something else. i dont know where the ground wire leads to on the stock tach, i do know that most of the stock tachs are not very accurate and need to be rebuilt. how long has it been reading off? has it ever read correctly?

[Russell]

That is one of the signs of a tach headed south -- Reading too high... You can check out www.73-78.com for more information.

I hate to leave a plug, but I do have a spare one that'd look real nice in there for sale on the parts board, lol

[82c10]

i believe he meant, www.73-87.com, i asked my auto service teacher, he said it's either a ground, which your going to have to look at wiring schematics to find out where it should be, or like Russell said it's about to quit

[Russell]

thanks for the correction 82c10 -- I just type too fast for my own good, lol

[f.monroe]

Look above the left (drivers) kick panel .There should be a gang connector and the tach ground hooks to the top of it . It is just a female blade connector . The wire comes off of the instrument panel on the back side of the tach . There are only three wires , 12 v , Ground , and ignition which goes to the distributor . If you look under the dash you will see the wires . You might also want to check all of the under hood frame and body grounds . Frank

[Dano69c10]

Thanx everyone! I'll look at it this weekend.
Dano

[Hoods69BadBowTie]

My buddy had a stock tach doing the same thing for a little while, ground did not fix it and then it was shot. Got a nice aftermarket one and no problems since then.
-Later

[77gmcjoe]

Originally Posted by Hoods69BadBowTie

Got a nice aftermarket one and no problems since then.
-Later

Ya gotta love them factory tachs, though.
It's usually the first thing I look for when I see an interior pic.

And yeah, I've seen them reading high when they're going bad.