Results 1 to 9 of 9

Thread: Tacho Jumps...

  1. #1

    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.

  2. #2
    Goldmember ttweed's Avatar
    Join Date
    Oct 2002
    Location
    La Jolla, CA
    Posts
    1,429
    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
    Tom Tweed
    Early S Registry #257
    R Gruppe #232
    Rennlist Founding Member #990416-1164
    PCA National DE Instructor
    Read my surf novel!

  3. #3
    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
    Reading the PP forum now... My '67S has the Crane Ignition module installed by the P.O.

    Sprint.

  4. #4
    Originally posted by ttweed
    Sprint-
    Go to the PP forum and read TT
    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.

  5. #5

    rev limiter

    Maybe?

    Shawn.
    67 coupe roller
    99 M96 2.5 litre
    early911s reg 447
    R Gruppe 399

  6. #6

    Re: rev limiter

    Originally posted by Shawn
    Maybe?

    Shawn.
    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.

  7. #7

    Re: rev limiter

    Originally posted by Shawn
    Maybe?

    Shawn.
    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.

  8. #8

    not rev limiter

    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.

    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. Not recommended for and already low rpm torque challenged car.
    67 coupe roller
    99 M96 2.5 litre
    early911s reg 447
    R Gruppe 399

  9. #9

    Re: not rev limiter

    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.

    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. Not recommended for and already low rpm torque challenged car.
    Ho ho... Have a nice weekend Shawn!!!

    Sprint.

Similar Threads

  1. Swb 1967 speedometer jumps
    By frankmar in forum Technical Info
    Replies: 2
    Last Post: 05-20-2013, 04:33 AM
  2. 10K tacho
    By one-two in forum For Sale: 911 Parts
    Replies: 2
    Last Post: 09-02-2012, 11:46 AM
  3. 10,000 rpm Tacho
    By mrg3.6 in forum General Info
    Replies: 2
    Last Post: 05-07-2008, 02:01 PM
  4. 911 R tacho
    By ydderf911 in forum Technical Info
    Replies: 2
    Last Post: 11-28-2006, 08:25 AM
  5. Oil Level gauge jumps
    By Bobs 67S in forum Technical Info
    Replies: 1
    Last Post: 10-23-2002, 10:44 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.