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Product # 3991

  • 3-3/8" (85.7mm)
  • Air-Core Air-Core
  • 0-8,000 RPM
  • Incandescent
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Since 1957, AutoMeter has set the standard in performance, accuracy and durability with their legendary Tachometers. The absolute pinnacle of engineering and technology, it’s no wonder AutoMeter can lay claim to more motorsports victories than every other gauge manufacturer combined. The patented air core meter movement, wound in house to exacting standards, can move the needle from 0 - 10,000 rpm in 333 milliseconds. An inaugural inductee to the Hot Rod Speed Parts Hall of Fame, no other tachometer on the market has had anything approaching its impact on professional racing. Built for a lifetime of service under the harshest conditions, this is the no compromise tach for no compromise builds. When you’re ready for the best, there isn’t another choice.

Feature Points

  • Traditional incandescent lighting illuminates around the perimeter of the dial
  • Compatible with most 4, 6, and 8 cylinder engines (2 - 4 pulse per revolution ignition signals) with points, electronic, and most 12V high-performance racing ignitions.
  • 12 and 16 volt compatible, well-suited with nearly every street car or race car electrical system
  • Gauge kit includes bulb and socket assembly, red and green bulb covers, mounting hardware, and detailed instructions for installation
  • AutoMeter’s race proven air-core electric tachometers provide quick and accurate readings with a needle so responsive it can go from 0 - full scale in 333 milliseconds

Bulb & Socket

  • 3212

Light Covers

  • Red 3214 & Green 3215

Mounting Hardware

  • Bracket Included
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Recently order the Tachometer 105-3991.. I'm wanting to mount it on my Steering column mount for my 74 Bronco. It's required a 3 3/8" Tach and once I received my order, it reads 3 3/4" on the box. Is there a typo or is that the face size?

Asked by: Jase
Hi Jase, thank you for reaching out to us. The 3991 fits into a 3-3/8" diameter hole, but the bezel diameter is 3-3/4". We've tried to remain more consistent by referencing hole size on in-dash instruments, but may have some older label descriptions that reference the bezel diameter of 3-3/4".
Answered by: Matt from AutoMeter
Date published: 2018-08-25

The autometer 3991 tach does not come with standard lighting pigtail. How do I access the light to use the supplied bulb accessories (little rubber things to change the color of the light)?

Asked by: Darren
Hi Darren, thank you so much for contacting us. The socket is inside the housing of the tach itself. Simply pry off the black cover on the back of the tach and you can use a set of needle nose pliers to remove the socket inside. It's a 1/4 turn counterclockwise and it will come right out. Hope this helps!
Answered by: Joseph At AutoMeter
Date published: 2018-06-25
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