Topic: Tach problem on my 76 w/4spd
in Forum: C3 Electrical

Moderator
It seems my tach starts acting eratic if it spends to much time at 3500 rpm. If I run at 75 mph for more than a 1/2 hour it will drop down and bounce around 2000 to 2500 rpm. If I get off the freeway and drop my speed down to 60 mph the tach will work fine. Do I have a filter problem?
Thanks

Moderator
The problem could be the tach itself(gauge). Could be a little gummy, or sumpthin.
It could be the circuit board(ribbon), on the rear of the tach/speedo panel, or the connection thereof.
It could also be a problem with the ign. module, or coil connection.
I think I would start checking the connection at the dist. cap first, and make sure it is good & tight, with no corrosion, or moisture. Then you might need to pull the dash pad down & check the connections on it.

Hopefully, someone else here will have more info on this particular problem.

Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Moderator
Thanks Adam,
There is a filter on the back of the intake manifold but I did not see it in my electrical schematic. It seems to act up only after spending 1/2 hour running at 3000 to 3500 rpm. I do want to go through and recheck the wires like you said. I realllly do not want to pull the dash. I did a complete interior rebuild last winter and getting the dash all back to gether was not fun. The problem did happen before the interior rebuild so I don't think that is it.
On a good note, my sunburn from the Skykomish show is gone

Moderator

Joel Adams
C3VR Lifetime Member #56
My Link
(click for Texas-sized view!) NCRS
"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

1978 L82 4speed
1994 LT1 6speed