Tach not working right, but still working?

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Tach not working right, but still working?

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Corvette Forums >> Corvette Models >> Corvette C3 Forum >> Tach not working right, but still working?

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Tach not working right, but still working? - 4/25/2008 10:05:15 PM

DryCreamer

Posts: 89
Joined: 1/28/2008
From: Muncie, IN
Status: offline

Finally got my car together and got it out of Steve's garage. :) Got the engine running great! Its got a fantastic lope, and got the rear wheels lined up (or at least better than what it was) and I got flowmaster Super 40's on it that sound GREAT! Here's the deal:

I had a part throttle backfire that was driving me crazy and one day while I was out "diagnosing" it (read: mashing the gas) my car started to miss REALLY bad, and what happened was the hold down bolt for the distributor popped out of the intake and the timing went WAY advanced. So I heli-coiled the intake got it all back together and running good, but when I shut the car off, the tach sits at 2000 RPM and it idles at 2000 RPM.

Is there a way to re-set or zero the tach on an '81. It was the first year for the computer and I saw on some diagrams that the tach wire (its yellow with a little condensor on it) runs through the engine computer, but it was working fine with no computer hooked up until my timing went all wacko.

I didn't know if any of you guys have ever had this happen or if its even a common problem with the early 80's Vettes.

PS: I got video of the first fire up, and of the car with stock muffler, NO MUFFLERS, and Flowmasters so hopefully when I get back in town, I'll be able to post them to You tube or something and put them up.

Thanks!

_____________________________

Clayton

Post #: 1

RE: Tach not working right, but still working? - 4/26/2008 11:34:59 AM

78buckshot

Posts: 614
Joined: 1/28/2007
From: Michigan
Status: offline

Hi Clayton, the tach on my '78 will stop at an irrelevant position when I turn it off. I replaced the tach control board because it was way out of whack, I think the capacitor may also need replacement because the tach will change 50 - 100 RPM when I turn on the lights or other electrical load. Are you sure the engine isn't actually idling at 2000 RPM when you shut it down?

(in reply to DryCreamer)

Post #: 2

RE: Tach not working right, but still working? - 5/5/2008 3:03:47 PM

DryCreamer

Posts: 89
Joined: 1/28/2008
From: Muncie, IN
Status: offline

Sorry, been in Jersey for 4 days...

Nope, it is definitely idling at 600, I'm going to Steve's house tonight, I;ll see if he can get those video's of it on the computer today

(in reply to 78buckshot)

Post #: 3