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    Results 1 to 9 of 9
    1. #1
      Join Date
      Apr 2018
      Location
      Oakland
      Posts
      68

      LS Swap 69 Camaro tach question

      Hey,

      I had wired my factory tach signal wire to my LS harness tach lead. My factory tach is grounded and works. Only thing is, the respond on the tach is slow. Any opinion?

      I had tried giving the tach more juice by wiring a 1k resistor from a Key on 12v source to the tach signal but its still the same respond. Maybe the 1k resistor was a bad one.

    2. #2
      Join Date
      Jul 2006
      Location
      Pensacola, FL
      Posts
      1,263
      Country Flag: United States
      I have always had to use a tach adapter to make a factory style tach work when doing an LS swap. I am not saying it's the only way, but it has worked for me.

      https://www.amazon.com/Auto-Meter-91...61213412&psc=1

    3. #3
      Join Date
      Apr 2018
      Location
      Oakland
      Posts
      68
      That a good price for that unit. Thanks. If all other fail, I have no problem getting this.

    4. #4
      Join Date
      Feb 2011
      Location
      dallas, tx
      Posts
      1,729
      Country Flag: United States
      Did you switch the gauge to 4 cylinder mode? The resistor connects to a 12v source inline to the the tach signal. Only issue i have is that it bounces some at idle.

    5. #5
      Join Date
      Jun 2013
      Location
      Central FL
      Posts
      102
      Country Flag: United States
      Quote Originally Posted by oakhill510 View Post
      Hey,

      I had wired my factory tach signal wire to my LS harness tach lead. My factory tach is grounded and works. Only thing is, the respond on the tach is slow. Any opinion?

      I had tried giving the tach more juice by wiring a 1k resistor from a Key on 12v source to the tach signal but its still the same respond. Maybe the 1k resistor was a bad one.
      What inspired the resistor mod? Was it something you read somewhere? I haven't heard of it but I haven't researched LS swaps either.

      Putting a 1k resistor inline with a 12v source means you would only get a Max of 12mA current to drive the tach motor. Giving it less resistance will increase the drive strength but I don't know if there's a current rating that you have to stay under to avoid burning the tach up.
      James
      1969 Mustang Fastback

    6. #6
      Join Date
      Jun 2001
      Location
      Newbury Park, CA
      Posts
      5,821
      Country Flag: United States
      The tach in my Camaro, updated with a modern VDO movement, at first worked well with the LS swap then started acting erratically. The problem was a low signal voltage.

      The cure is a 5k resistor with one end to the tach wire and the other to IGN+.
      VaporWorx. We Give You Gas http://www.vaporworx.com

    7. #7
      Join Date
      Apr 2018
      Location
      Oakland
      Posts
      68



      icemanrd19
      I
      am using a factory 69 Camaro tach. Theres no cylinder mode option.


      69_Sportsroof as for the resistor mod, I believe from what I read that, LS pcm doesn send low power to the LS tach wire and 69 Camaro (and older tachs) uses/need more power juice than the LS/modern tachs. So the 1k resistor mod boost the power on the LS send tach wire.
      One souce : https://www.youtube.com/watch?v=FS7aRfYkFAQ&t=365s



      fixed your low signal voltage with a 5K resistor huh.....? I need to try that. Thanks.



      Sorry about the late replies, I dont get notifications.

    8. #8
      Join Date
      Apr 2018
      Location
      Oakland
      Posts
      68
      Heres the video of the tach working on youtube.



      https://www.youtube.com/watch?v=gnGNGaSAIVU

    9. #9
      Join Date
      Jan 2014
      Location
      Portsmouth NH
      Posts
      247
      Country Flag: United States
      Here is some more info that might help you.



      Cheers, Steve

      https://forum.hptuners.com/showthrea...autometer+tach
      1969 Camaro (Small Tyre Restomod/mild Protour) 245/40/18 F, 275/35/18 R, stock frame, full Ridetech suspension, LS engine, T56 Mag, Wilwood Brakes. A driver car.






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