different tach's??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BUXMAN66 · 12-30-2003, 08:04 PM

i bought a tach dash off of e-bay (board member),and after doing some talking w/ the guy's at restoration world (full line of gm cars and trucks restoration parts)...and then his supplier.....american autowire......i now have been told that there might be a possibility that even w/ the correct style harness to hook up w/ my hei ignition...that gm had different styles of tach's and that some were only compatible w/ points/coil style of ignition. can anyone shed some light on the subject.....and also what the hell am i gonna do w/ a coil type tach...and i've got the hei style ignition?? any way of knowing/identifying this beforehand or is it just hook it up and hope??

1969 GMC · 12-30-2003, 08:08 PM

all 67-72 trucks had points style ignition. many people have converted their truck to HEI, and the tach works fine...sounds like the resto guys are blowing smoke up your a$$? you may have to wire the tach differently, but I dont know about this.

jhow66 · 12-30-2003, 08:14 PM

What color wires does your tach have?

BUXMAN66 · 12-30-2003, 08:19 PM

my thoughts exactly!! the guy at american autowire did give specific instances though....the early 60's years trucks, and others i dont remember exactly. he said the points style of tach read the pulse given off the coil...and that the circuitry was different......??

BUXMAN66 · 12-30-2003, 08:21 PM

i haven't recieved the tach yet ......from the big brown truck!!

jhow66 · 12-30-2003, 08:21 PM

What brand?

BUXMAN66 · 12-30-2003, 08:30 PM

it's a factory tach dash check it out: http://cgi.ebay.com/ebaymotors/ws/eb...tem=2449136434

jmanz69 · 12-30-2003, 08:33 PM

They all read the pulse off the coil. The HEI has a terminal that is labeled TACH. Just hook up the lead that would normally go to the (-) side of the coil and you are set. I think he may have been trying to get you buy something he has to sell. Whether it's a pionts or HEI, the tach is on the (-) side of the coil. It's the same reading, just a different location.

s95930 · 12-30-2003, 08:35 PM

I think they are confused. When I use my tune up tach on vehicles with points and vehicles with HEI. I don't do anything other than hook up the wires. I assume the tach in the dash works on the same principle.

jhow66 · 12-30-2003, 08:42 PM

Nice looking dash. Just finished a setup just like yours for my brother-in-law. Coil terminal on tach goes to tach terminal on HEI. Other terminal on tach goes to a 12 volt switched source. These tachs work with both HEI or points as I have installed both ways .

BUXMAN66 · 12-30-2003, 08:44 PM

i don't see how he really has anything to gain by it but........i personally thought the only differences were a mechanical tach and a electrical tach.... there isn't any difference in the price for either harness.......whatever?!?

BUXMAN66 · 12-30-2003, 08:46 PM

thanks to all w/ the replies....i don't just plop down $400 bucks everyday y'know?!!!lol

Longhorn Man · 12-31-2003, 01:00 AM

A mechanical tach would run off a cable like on the old 63 (I think it was 63) Corvettes and on many old deisel engines.

Rooster's 67 · 12-31-2003, 04:58 AM

only issue you could have is there is actually a tach for 6cyl and 8cyl and they are different. the back of the tach will be stamped, mine reads 8CYL but very faintly.

BUXMAN66 · 01-01-2004, 06:29 PM

everything's been taken care of...in fact i've heard from the guy that i bought it from and he assured me that it is the same tach that he has in his own truck,...and running a hei.

GMC Jim · 01-03-2004, 08:48 AM

If you want a tach that is just a little " different"..... Teleflex has a line of tachs used with marine engines.....Most are 6000/7000 RPM and are available in several styles, background plate colors etc....

*1972C10* · 01-04-2004, 03:30 AM

I had a really neat tach one time i got my 72 hooked it up the first day second day i upgraded to an hei it woudlnt work with the hei had to have the external coil ended up giving to a friend with a mid 80s ford. Some tachs wont work with hei mainly older ones.,

Hooter · 01-04-2004, 03:36 AM

they tachs are all the same same reguardless of 6 cyl or 8, there is a set screw in the back of the tach to select either 6 or 8 cyl

1969 GMC · 01-04-2004, 05:53 AM

the only different tach is the diesel tach out of a medium duty truck, which is only labeled to 4k, as opposed to 5k on all gas trucks.

12-30-2003, 08:04 PM	#1
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	different tach's??? i bought a tach dash off of e-bay (board member),and after doing some talking w/ the guy's at restoration world (full line of gm cars and trucks restoration parts)...and then his supplier.....american autowire......i now have been told that there might be a possibility that even w/ the correct style harness to hook up w/ my hei ignition...that gm had different styles of tach's and that some were only compatible w/ points/coil style of ignition. can anyone shed some light on the subject.....and also what the hell am i gonna do w/ a coil type tach...and i've got the hei style ignition?? any way of knowing/identifying this beforehand or is it just hook it up and hope?? __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-30-2003, 08:08 PM	#2
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	all 67-72 trucks had points style ignition. many people have converted their truck to HEI, and the tach works fine...sounds like the resto guys are blowing smoke up your a$$? you may have to wire the tach differently, but I dont know about this. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

12-30-2003, 08:14 PM	#3
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	What color wires does your tach have? __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-30-2003, 08:19 PM	#4
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	my thoughts exactly!! the guy at american autowire did give specific instances though....the early 60's years trucks, and others i dont remember exactly. he said the points style of tach read the pulse given off the coil...and that the circuitry was different......?? __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-30-2003, 08:21 PM	#5
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	i haven't recieved the tach yet ......from the big brown truck!! __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-30-2003, 08:21 PM	#6
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	What brand? __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-30-2003, 08:30 PM	#7
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	it's a factory tach dash check it out: http://cgi.ebay.com/ebaymotors/ws/eb...tem=2449136434 __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-30-2003, 08:33 PM	#8
jmanz69 Careful, they attack... Join Date: Aug 2001 Location: Waterford, MI, USA Posts: 1,107	They all read the pulse off the coil. The HEI has a terminal that is labeled TACH. Just hook up the lead that would normally go to the (-) side of the coil and you are set. I think he may have been trying to get you buy something he has to sell. Whether it's a pionts or HEI, the tach is on the (-) side of the coil. It's the same reading, just a different location.

12-30-2003, 08:35 PM	#9
s95930 A-Adam A-Adam Join Date: Apr 2003 Location: Sarpy Co. Ne. South of Omaha Posts: 263	I think they are confused. When I use my tune up tach on vehicles with points and vehicles with HEI. I don't do anything other than hook up the wires. I assume the tach in the dash works on the same principle. __________________ 70 3/4 ton GMC Camper Special

12-30-2003, 08:42 PM	#10
jhow66 Registered User Join Date: Jun 2002 Location: Knoxville Tenn. Posts: 3,058	Nice looking dash. Just finished a setup just like yours for my brother-in-law. Coil terminal on tach goes to tach terminal on HEI. Other terminal on tach goes to a 12 volt switched source. These tachs work with both HEI or points as I have installed both ways . __________________ 56 Chevy Bel-Air 2dr. HT (purchased new) 71 Chevy Cheyenne SWB PU (502HO) 65 GMC short bed step--work in progress and my gofer

12-30-2003, 08:44 PM	#11
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	i don't see how he really has anything to gain by it but........i personally thought the only differences were a mechanical tach and a electrical tach.... there isn't any difference in the price for either harness.......whatever?!? __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-30-2003, 08:46 PM	#12
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	thanks to all w/ the replies....i don't just plop down $400 bucks everyday y'know?!!!lol __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?

12-31-2003, 01:00 AM	#13
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	A mechanical tach would run off a cable like on the old 63 (I think it was 63) Corvettes and on many old deisel engines.

12-31-2003, 04:58 AM	#14
Rooster's 67 Registered User Join Date: Sep 2003 Location: DFW Posts: 765	only issue you could have is there is actually a tach for 6cyl and 8cyl and they are different. the back of the tach will be stamped, mine reads 8CYL but very faintly. __________________ The problem with America is stupidity. I'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety labels off of everything and let the problem solve itself?

01-01-2004, 06:29 PM	#15
BUXMAN66 go bucks! Join Date: Jan 2002 Location: MIAMISBURG OHIO USA Posts: 803	everything's been taken care of...in fact i've heard from the guy that i bought it from and he assured me that it is the same tach that he has in his own truck,...and running a hei. __________________ '68 swb 1/2t 350/350th '86 lngbd 3/4 TON parts getter '49 gmc 1/2 t 5 window 350/350th '96 gmc sonoma sle ext-cab. hey it's a 4cyl. 5 spd and good on gas y'know?



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01-03-2004, 08:48 AM	#16
GMC Jim Senior Member Join Date: Dec 2002 Location: Portland, Oregon Posts: 901	If you want a tach that is just a little " different"..... Teleflex has a line of tachs used with marine engines.....Most are 6000/7000 RPM and are available in several styles, background plate colors etc.... __________________ '71 GMC;fleetside;PB/PS/AC/CC/402 Eng./Custom Paint/110,000act miles/3 fuel tanks(52gal).

01-04-2004, 03:30 AM	#17
1972C10 Account Suspended Join Date: Dec 2003 Location: Texas Posts: 2,686	I had a really neat tach one time i got my 72 hooked it up the first day second day i upgraded to an hei it woudlnt work with the hei had to have the external coil ended up giving to a friend with a mid 80s ford. Some tachs wont work with hei mainly older ones.,

01-04-2004, 03:36 AM	#18
Hooter My other Love Join Date: Aug 2001 Location: Castlegar B.C. Canada Posts: 4,078	they tachs are all the same same reguardless of 6 cyl or 8, there is a set screw in the back of the tach to select either 6 or 8 cyl __________________ MEMBER DISCS UP FRONT CLUB 69 custom camper/cst 10 70 monte carlo 383 stroker with a 700r4 77 fully loaded silverado (back in the backyard for a little while longer) 1980 BMW 320i (back in the garage finally) 1981 f@*d f150 4x4 (Robert red ford) tried to kill me 1972 Honda ct 90 trailbike Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com AC/DC RULES!!! First generation Monte Carlo club pictures of my life

01-04-2004, 05:53 AM	#19
1969 GMC Registered User Join Date: Feb 2003 Location: The Rubber City Posts: 5,498	the only different tach is the diesel tach out of a medium duty truck, which is only labeled to 4k, as opposed to 5k on all gas trucks. __________________ 1969 GMC K2500 1996 Honda Accord 2007 Kawasaki KLR 650

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