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Apr 26th, 2026 | | AD Chevy Trucks  Over 6,000 pictures Brad Allen has an awesome collection of Chevrolet factory pictures that he has set up from film strips. Check them out!
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| | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | I have a hei inline 250 motor in my '49. The distributor has a wire connection for a tach, but I need to know what tach will work with what I have. I just want a simple little 3" tach- nothing special, but never delt with this before. Thanks for the help!
Jeremy | | | | | Joined: Apr 2005 Posts: 926 Shop Shark | | Shop Shark Joined: Apr 2005 Posts: 926 | If you're buying new,pretty much any tach should work fine for you. I have a a Faria tach in my '74 Chevy truck that only works with a V-8,and a couple of 1980's (?) SunPro tachs I'm using on my older trucks;they're adjustable for a 4,6 or 8 cylinder engine,will work with points or HEI ignition. Don't know if they work on six volts (I remember seeing that mentioned on one of the truck forums recently), or how to set up for positive ground,but SunPro's Tech line people could likely answer that for you. These tachs sell for 50-60 bucks at most parts stores.
Speed | | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | I didn't know if I should be looking for tach with a certain amount of hookup wires (kinda like a 1 or 3 wire alternator), mechanical or electric, how many cylinders or if they're all compatable. | | | | | Joined: Feb 2004 Posts: 29,868 Kettle Custodian (pot stirrer) | | Kettle Custodian (pot stirrer) Joined: Feb 2004 Posts: 29,868 | If you're running a 12 volt, negative ground electrical system, you've got a bunch of options. Original 6-volt systems, or any system with positive ground narrows the field a bunch. Check out the JEGS catalog, or possibly PAW, and you'll find a wide variety of designs and prices.
Just pick one that fits the mounting position you want, and be sure it has a 4-6-8 cylinder selection capability. Most tachs will have at least 4 wires, (+) and (-) power connections, a trigger lead that goes to the distributor, and a wire that attaches to the dash light circuit for illumination. Some of the high-end tachs will include circuitry for rev limiters, shift lights, etc. Unless you're racing, those features aren't necessary.
Jerry
"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!
| | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Can use SunPro or others on 6v system with voltage booster.
The bigger the face the better the resolution, stay away from the small dia tach.
Denny Graham
Sandwich, IL
Denny G
Sandwich, IL
| | | | | Joined: May 2006 Posts: 103 Wrench Fetcher | | Wrench Fetcher Joined: May 2006 Posts: 103 | okay thanks guys! The truck is a 12 volt system so that should make it easier. | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Gnd, hot wire, signal wire from the dist. That's all there is to it if your 12v.
Denny G
Denny G
Sandwich, IL
| | | | | Joined: Oct 2006 Posts: 4,983 Master Gabster | | Master Gabster Joined: Oct 2006 Posts: 4,983 | Denny, why do you say stay away from the small diameter tach?
~Jim
| | | | | Joined: Jan 2008 Posts: 227 Shop Shark | | Shop Shark Joined: Jan 2008 Posts: 227 | "Cause if you're half blind like me..........
Ya can't see the buggers!
Go the Monster 5" Tach like me and not only does it block half your view.......the bloody shift light blinds you at night!
Go for what fits your interior and eyesight best. | | | | | Joined: Oct 2006 Posts: 9,671 'Bolter | | 'Bolter Joined: Oct 2006 Posts: 9,671 | Circumference Big, the larger the circumference the better defined or higher the resolution of the scale. On the 2” face it is very difficult to read closer than a couple hundred rpm, bump that up to a 3”or 4” face and now you can accurately read with in 50 rpm. I suppose the easiest way to explain what I mean is with a picture. Try this: http://rides.webshots.com/photo/2513482700098611668dGaxvt Which one would you rather try to read while bouncing around at 55mph? Denny Graham Sandwich, IL
Denny G
Sandwich, IL
| | | | | Joined: Oct 2006 Posts: 4,983 Master Gabster | | Master Gabster Joined: Oct 2006 Posts: 4,983 | Makes sense. I just thought your eyes were going bad. 
~Jim
| | | | | Joined: Dec 2006 Posts: 1,154 Shop Shark | | Shop Shark Joined: Dec 2006 Posts: 1,154 | HI....I was hoping that somebody(s) with a 235 and HEI would chime in and let us know which brand, part number, and from where they purchased their tach. A lot of us want a tach but there are so many choices and which ones (types) will work well in our trucks? Hope to hear from some of you and T/C Steve | | |
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