how to test a tach??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**71blksuper4x4** · 11-16-2009, 04:02 PM

Hey guys, I am trying to figure out how to test out a tachometer to see if it works. What is a way to test it without it being in a vehicle? I remember there is ways to do it with power to it, but I don't remember the process. Thanks guys, Trevor

72BlckButy · 11-16-2009, 04:03 PM

Signed in for this one too...

**LockDoc** · 11-16-2009, 04:38 PM

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I don't know why you couldn't lay the cluster or tach on the cab floor or seat, run a jumper wire to the "unfused ignition" terminal on the fuse panel, one to the HEI "Tach" connector on the distributor, one to ground, and start the truck up.

LockDoc

**71blksuper4x4** · 11-16-2009, 04:42 PM

Leon, well this is a camaro tach dash conversion I want to test and then sell. I just want to make sure that the tach works before I sale. My truck is out of commission right now, but we have a gm truck that we could hook up to the dizzy. Thanks Jim for your help as well. Trevor

JimKshortstep4x4 · 11-16-2009, 04:37 PM

The way I test a tach is to hook power to the tach, (ground the case, positive to the + post on the tach). I then run a wire to the "Tach" connection of an HEI distributor or to the - side of a coil if points are used.

If a tach is good it will register the rpm. If it is out of calibration I use my Snap-On Tachometer as a reference to adjust the tach to. Both tachs can be hooked up at the same time.

I have also used my distributor machine to test tachs on and it is a similar procedure but instead of a battery, I use a 12 volt DC battery charger.

Jim

11-16-2009, 04:02 PM	#1
71blksuper4x4 SWB 4x4 Collector Join Date: Jun 2001 Location: Osage City, KS Posts: 5,152	how to test a tach??? Hey guys, I am trying to figure out how to test out a tachometer to see if it works. What is a way to test it without it being in a vehicle? I remember there is ways to do it with power to it, but I don't remember the process. Thanks guys, Trevor __________________ TREVOR 1970 CST swb 4x4 (speedwarning,cruise,tilt,tach,8track, original red shoulder belts,tow hooks) 1972 Jimmy (soon to be Hickey cloned) 1971 Cheyenne Super 4x4 swb (tilt,tach,buckets, original blue shoulder belts,am/fm,cruise,tow hooks, dealer 8 track) 1972 Cheyenne Super K20 4x4 Custom Camper (tilt, tach, am/fm, tow hooks, bed toolbox, aux gas tank 1972 Cheyenne Super Crew Cab K30 4x4 Duramax, Allison, np205, buckets, tow hooks (CURRENT PROJECT) http://67-72chevytrucks.com/vboard/s...d.php?t=624819 1989 V3500 Crew Cab (454tbi, NV4500, np205) 1970 Chevelle SS (LS5 454,th400,8track,buckets,tach) :2004 Jeep Wrangler Rubicon (daily driver) WTB: 1968-70 Cruise Control Lever

11-16-2009, 04:03 PM	#2
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: how to test a tach??? Signed in for this one too... __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

11-16-2009, 04:38 PM	#3
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,465	Re: how to test a tach??? - I don't know why you couldn't lay the cluster or tach on the cab floor or seat, run a jumper wire to the "unfused ignition" terminal on the fuse panel, one to the HEI "Tach" connector on the distributor, one to ground, and start the truck up. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

11-16-2009, 04:42 PM	#4
71blksuper4x4 SWB 4x4 Collector Join Date: Jun 2001 Location: Osage City, KS Posts: 5,152	Re: how to test a tach??? Leon, well this is a camaro tach dash conversion I want to test and then sell. I just want to make sure that the tach works before I sale. My truck is out of commission right now, but we have a gm truck that we could hook up to the dizzy. Thanks Jim for your help as well. Trevor __________________ TREVOR 1970 CST swb 4x4 (speedwarning,cruise,tilt,tach,8track, original red shoulder belts,tow hooks) 1972 Jimmy (soon to be Hickey cloned) 1971 Cheyenne Super 4x4 swb (tilt,tach,buckets, original blue shoulder belts,am/fm,cruise,tow hooks, dealer 8 track) 1972 Cheyenne Super K20 4x4 Custom Camper (tilt, tach, am/fm, tow hooks, bed toolbox, aux gas tank 1972 Cheyenne Super Crew Cab K30 4x4 Duramax, Allison, np205, buckets, tow hooks (CURRENT PROJECT) http://67-72chevytrucks.com/vboard/s...d.php?t=624819 1989 V3500 Crew Cab (454tbi, NV4500, np205) 1970 Chevelle SS (LS5 454,th400,8track,buckets,tach) :2004 Jeep Wrangler Rubicon (daily driver) WTB: 1968-70 Cruise Control Lever

11-16-2009, 04:37 PM	#5
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Re: how to test a tach??? The way I test a tach is to hook power to the tach, (ground the case, positive to the + post on the tach). I then run a wire to the "Tach" connection of an HEI distributor or to the - side of a coil if points are used. If a tach is good it will register the rpm. If it is out of calibration I use my Snap-On Tachometer as a reference to adjust the tach to. Both tachs can be hooked up at the same time. I have also used my distributor machine to test tachs on and it is a similar procedure but instead of a battery, I use a 12 volt DC battery charger. Jim __________________ 1971 Shortbox step side 4x4, 350 sbc, 3:07 rear end 1965 Impala SS 400 sbc, Muncie rock crusher 1966 Impala SS 396 bbc, TH 400 1969 El Camino, 350 sbc, TH 350 1971 Snowplow built on a Blazer frame 1972 GMC Short bed, stepside, TH 400, 427 BBC Last edited by JimKshortstep4x4; 11-16-2009 at 04:41 PM.



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