Black on Black 1967 Camaro L78 124377N212598

[Mr70]

Nice trouble shooting on the Primary lead wire.Was just talking to someone about your camaro and couldn't find this topic.
Thanks for bringing it back to the top.

[SuperNovaSS]

Awesome update Jose. You are living the dream JB.

Jason

[BJCHEV396]

Originally Posted by SuperNovaSS

Awesome update Jose. You are living the dream JB.

Jason

X2!!

[AnthonyS]

X3!!!

[jbtech]

Finally got around to adjusting the tach. I removed the driver seat, laid on my back with my head/arm behind the dash. With a small screwdriver I adjusted the tach and this is best I could get it. From idle to 2000rpm it reads around 150-200rpm too high but from 2000-7000rpm it's dead on. Prior to adjustment, when I was cruising at 2800rpm the tach would read around 3500rpm. The tach photo is when receiving a 3000rpm signal.

I also mocked up the line lock button.

[scuncio]

How were you able to adjust the tach needle?

[jbtech]

Originally Posted by scuncio

How were you able to adjust the tach needle?

Jason's advice and photo from post 270:

Originally Posted by SuperNovaSS

There is a potentiometer on the back of the tach behind this sticker to adjust the rpm reading. Just be careful, the potentiometer can be fragile after all these decades.


Jason

I used a very small flathead screwdriver and with the power off I ever so slightly turned the what I'm assuming is the potentiometer screw counter clockwise. I retested and repeated until it was accurate to my liking. I read that it's possible to cause a short if the screwdriver touches the housing during adjustment which is why I did mine with the power off. It was tricky and I couldn't even see inside the opening for the potentiometer but I as I gently turned the screwdriver with the tips of my fingers I waited for it to fall into the slot, Once in the slot I felt a resistance as I turned the screwdriver. Luckily it only needed 2 adjustments. After adjustment I replaced the painters tape that I used to cover the hole.
With all of that said the tach needle itself when the car is off rests about 100-200rpm too high, but since my readings were accurate from 2000-7000rpm after adjustment it was fine by me.

[SuperNovaSS]

Jose,

Did the tach always “zero”
At 100-200 or was that after the adjustment. Moving the potentiometer shouldn’t affect the zero reading.

I love the chrome line lock button. Fancy!

Jason

[jbtech]

Originally Posted by SuperNovaSS

Jose,

Did the tach always “zero”
At 100-200 or was that after the adjustment. Moving the potentiometer shouldn’t affect the zero reading.

I love the chrome line lock button. Fancy!

Jason

To clarify the tach never did rest at zero. The adjustment did not alter the resting position but it did make a huge improvement in the overall accuracy of the tach. Here is a photo of the tach off/zero rpm.

[jbtech]

Here is my draft wiring diagram that will allow me to use the chrome lineloc button in traditional fashion for burnouts.

With the flip of a switch however, I can depress the clutch and hold the brake, the chrome button will only need to be pressed once, and will engage a latching relay that will hold the line loc and launch rpm limiter on the Omex clubman. When the clutch is released it will disengage both the line loc and launch rpm limit.

The omex clubman has 2 wires coming out of the box which connects to a normally open switch, when the circuit is closed it activated the 2 step. Other systems simply use a 12 volt feed. Anyway this is the reason for the 3rd relay.