Tacho Jumps...

Hi Guys...

My tacho started jumping last week.... Thought you might have experienced it before.... What causes it?

It's very normal during city driving up to 5k, 6k? But when I find an open stretch and I really pull, it seems to bounce off the 8k end and goes back to 1k and of coz by then, I've upshifted and it goes back to normal....

What's going on? Tacho on the way out? I've always heard that when the tacho bounces the alternator is going to die, but I don't think it's the same situation here...

And by the way, I've got a rew limiter rotor, so I don't tink I really hit 8k.... Haha...

Thanks in advance!

Sprint.

Sprint-
Go to the PP forum and read this thread and this one.
It could be a lot of things, from the tach itself going bad to a charging problem or a bad ground, to bad points, ignition wires or coil. It's a common problem but not an easy one to trouble shoot. Does your '67 have an aftermarket electronic ignition or stock?

Good luck,
TT

Quote:

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Originally posted by ttweed
Sprint-
Go to the PP forum and read this thread and this one.
It could be a lot of things, from the tach itself going bad to a charging problem or a bad ground, to bad points, ignition wires or coil. It's a common problem but not an easy one to trouble shoot. Does your '67 have an aftermarket electronic ignition or stock?

Good luck,
TT

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Reading the PP forum now... My '67S has the Crane Ignition module installed by the P.O.

Sprint.

Quote:

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Originally posted by ttweed
Sprint-
Go to the PP forum and read TT

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Hi Tom! I diligently read the posts but the problems seems different from mine. On my '67S, the tacho is fine at all lower rpms. Only when I drag and bring her up to near redline, does the needle spike and kinda like hit one wall (8K and bounces away to 1k). Then all is back to normal, only when I wind her up again...

Is Katie trying to tell me something?

Sprint.

Maybe? :confused:

Shawn.

Quote:

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Originally posted by Shawn
Maybe? :confused:

Shawn.

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Could be, but I don't think so... If it's rev cut, I would have felt a jerk...

Does it happen to you when you go past redline?

Sprint.

Quote:

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Originally posted by Shawn
Maybe? :confused:

Shawn.

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Ok... I did a few checks and I'm sure it's the tacho...

In idle, I slowly put my foot on the pedal and let the revs climb... At 5400rpm, the needle sorta snapped back to 0.

In 1st gear, I accelerated slowly and same thing, when I hit 5400rpm, it snaps back to 0 like a rubber band.

Same thing with 2nd and 3rd gear... Hehe... Beyond that, I'd prefer to keep my eyes on the road and not the speedo... :)

So what's happening? The tacho is otherwise fine. Reads good at rpms below 5400.

By the way, how did you know you got S cams in your '67? Can you see from taking off the valve covers while doing valve clearance work? *curious*

Sprint.

Yes, you would feel it, more than once if you keep your foot right in there. Or, at least that is what I am told. ;)

You need more experienced replies than mine. I don't know a volt from an amp or ohm to save my life.

The cams in my car were discovered during the engine rebuild (thanks to the previous owners check book) I keep it in my signiture to "fit in" with the s members. Got a real honest to god red s fan shroud outta the deal too. :D

Shawn.

edit: Oh, and you should know; when the only performance addition to an otherwise stock engine is a more agressive set of cams, the cars steetability suffers a bit. :rolleyes: Not recommended for and already low rpm torque challenged car.

Quote:

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Originally posted by Shawn
Yes, you would feel it, more than once if you keep your foot right in there. Or, at least that is what I am told. ;)

You need more experienced replies than mine. I don't know a volt from an amp or ohm to save my life.

The cams in my car were discovered during the engine rebuild (thanks to the previous owners check book) I keep it in my signiture to "fit in" with the s members. Got a real honest to god red s fan shroud outta the deal too. :D

Shawn.

edit: Oh, and you should know; when the only performance addition to an otherwise stock engine is a more agressive set of cams, the cars steetability suffers a bit. :rolleyes: Not recommended for and already low rpm torque challenged car.

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Ho ho... Have a nice weekend Shawn!!!

Sprint.