tach problems

tach problems on my 79 when i fire it up my reads 3500 rpm and when im driving it pegs out all they past 7000 rpm anyone had similar problems. mike 79

Hello Mike, and Welcome to the C3VR!
I'm not sure if the '79's had a inline "tach filter." If you look at the distributor cap and locate the wire that plugs into the terminal marked TACH, it's right next to the one marked BAT. Follow that wire back just a few inches, and if there is a thing that looks like a old lawnmower condensor thats plugged inline, then the car has one. Try replacing that first. If your car doesn't have it, then I'm guessing either a bad gauge or the printed circuit board may be faulty. Other than that I'm not sure. Let us know what you eventually find out.
Good Luck, Sarge

Mike:
Had my tachboard replaced last summer and I notice my rpms are registering too high as well, but no where near what you're experiencing. Idle is dead on where it should be, but at 60-70 mph I think the tach registers somewhere around 4,000rpm. From what I've seen on this site it should be more around 2,500rpm.

I'm going to take Sarge's advice when I can and look for that thingamabob filter thingy he mentioned. If you look before I do, let me know what you find out.

Do you think it could be the same problem in my '78...the tach is stuck at around 4500 rpms. According to the previous owner, it used to inch up a little each time he started it and I noticed it happening a couple times, too.

Thanks,
Franc

Franc,
Sorry so long responding, but I have not been able to get online as much as I used to. Before I changed out the board on my tach the needle was pegged all the way over to the right. Yours could be a more mechanical problem, but it would be worth a look to take it out and look at the board. If any of the resistors, etc. have fried you will be able to notice the burn mark on the board.

Good luck, hope you find the problem and get it fixed cheap!