tach - The 1947 - Present Chevrolet & GMC Truck Message Board Network

grinch4om · 05-23-2007, 08:05 AM

what's involved with installing a tach cluster into my 84 GMC? do I need the harness? etc..

Duro5341 · 05-23-2007, 04:56 PM

Use the search button, it works rather well

There is a whole right up on it

Duro

**Captkaos** · 05-23-2007, 05:52 PM

Read this: http://73-87.com/7387garage/interior...achometers.htm
Basically you need a cluster from a 78-up to work...

tyjoja · 05-24-2007, 12:42 AM

I tried a different cluster, not a tach, with guages to replace my idiot light cluster, in my 73. It goes in easy enough and the cluster plug fits, but not all the guages worked and some of the lights would not work. I checked some more and the wiring plug fit but my 73's did not have as many wires connected to it as the gauged cluster needed. I gave up and put my idiot cluster back in and hope to try the other cluster later and I'm hopefully less of an idiot

jdmaffeo · 05-24-2007, 11:02 AM

It is possible, but you will have to take your time. If you have idiot lights now, you will have to change out the sensors on the engine for water temp and oil pressure. You will also need the harness from the distributor to the tach! As far as the wiring goes, the clusters are all different. You will have to trace each wire in your plug and make note of it. Then you will have to trace the back of the circuit on the cluster to make sure that it is going to the right place. As I found I had to remove wires from the plug and put them in another place in the plug. Again take your time! Enjoy the pics!

chevysnbuicks · 05-24-2007, 12:05 PM

Don't mean to jack ur thread, but does anyone know what is involved in switching to a tach cluster in a '77?

**Captkaos** · 05-24-2007, 03:53 PM

You cannot put a 73-75 dash in anything BUT a 73-75 unless you plan to rewire the whole truck, the circuits are not the same. They use AMPS not volts, you could possibly Fry the whole setup.

read the supplied link..

As for swapping to a tach in a 77, If it isn't a 76-77 tach setup, you will need to rewire the harness also. Again, see supplied link.

Ivan D. · 05-24-2007, 06:23 PM

I read the article, it don't say much about the '79s - I got a truck with the gauges package, it's got a voltmeter, temp, and pressure (electric, not mechanical). I currently have an aftermarket tach, but I'd like to swap in a OEM tach cluster and move the aftermarket tach to my car. Does anyone know what donor truck I need to pull the tach cluster off? Thanks!

**Captkaos** · 05-24-2007, 07:00 PM

Quote:

Originally Posted by Captkaos

Read this: http://73-87.com/7387garage/interior...achometers.htm
Basically you need a cluster from a 78-up to work...

BTW, you need the whole cluster....

Ivan D. · 05-25-2007, 04:19 AM

Cool, thanks, that's what I thought too. And yes, I know I'll need the whole cluster, just wasn't quite sure which exactly whole cluster that is... of course now that I have the time and the money to go to the local U-Pull-It yard the weather's gonna be bad the whole weekend

tyjoja · 05-25-2007, 05:00 PM

Thank you captkaos, that looks like a great article. I was afraid that I had screwed up and got the wrong cluster so I ran out to my 73 and checked my guaged cluster that I had bought and it has a volt guage not amps. so I think I've got the right year. But I still remember thinking that something wasn't right, not all the cluster lights worked and the mech. press. guage didn't work etc. I may have hooked the pressure line into the wrong place on my block. It looked like the harness plug on the back did not have enough wires going to it, several wire spaces missing. I had that thing in and out about 10 times and finally ran out of patience and put the idiot lights back in. But thanks for the link, when motivated I want to try again sometime. thanks bob

Pyrotechnic · 05-25-2007, 09:33 PM

On the topic of gauge clusters, can I use a 78 Silverado speedometer in a 77 Sierra ?

The only difference I see in the clusters is that the oil pressure gauge in the 77 is mechanical and the 78 is electronic.

magnethead · 05-25-2007, 10:42 PM

the speedometer itself you probably can. Personally i like aftermarket external tach's better, little more sporty ans stil look clean when wires are hidden.

On a side topic, where's a good easy to get to wire that i can tap my tach light off of?

Pyrotechnic · 05-26-2007, 06:05 AM

Quote:

Originally Posted by magnethead

the speedometer itself you probably can. Personally i like aftermarket external tach's better, little more sporty ans stil look clean when wires are hidden.

On a side topic, where's a good easy to get to wire that i can tap my tach light off of?

I went directly to the headlight switch and found the wire that controls the gauge lights. I stuck a voltmeter on it and turned the dimmer and watched the voltage go up and down, this way I knew I had the right one.

05-23-2007, 08:05 AM	#1
grinch4om dang its hot Join Date: Nov 2006 Location: frankfort kentucky Posts: 1,349	tach what's involved with installing a tach cluster into my 84 GMC? do I need the harness? etc..

05-23-2007, 04:56 PM	#2
Duro5341 Registered User Join Date: Dec 2006 Location: Earth Posts: 239	Re: tach Use the search button, it works rather well There is a whole right up on it Duro __________________ -1986 K10 LWB, 350 HD,TH400 3.08, 30 spline 10 bolt, with an Auburn Posi, 31" tires All original, second owner truck -1979 Monte Carlo, 350, 200r4, 3.73 posi -1987 GT T-top Mustang - slow moving project

05-23-2007, 05:52 PM	#3
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: tach Read this: http://73-87.com/7387garage/interior...achometers.htm Basically you need a cluster from a 78-up to work... __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

05-24-2007, 12:42 AM	#4
tyjoja Registered User Join Date: Jan 2007 Location: albany oregon Posts: 168	Re: tach I tried a different cluster, not a tach, with guages to replace my idiot light cluster, in my 73. It goes in easy enough and the cluster plug fits, but not all the guages worked and some of the lights would not work. I checked some more and the wiring plug fit but my 73's did not have as many wires connected to it as the gauged cluster needed. I gave up and put my idiot cluster back in and hope to try the other cluster later and I'm hopefully less of an idiot

05-24-2007, 11:02 AM	#5
jdmaffeo Registered User Join Date: Dec 2005 Location: Dallas, TX Posts: 241	Re: tach It is possible, but you will have to take your time. If you have idiot lights now, you will have to change out the sensors on the engine for water temp and oil pressure. You will also need the harness from the distributor to the tach! As far as the wiring goes, the clusters are all different. You will have to trace each wire in your plug and make note of it. Then you will have to trace the back of the circuit on the cluster to make sure that it is going to the right place. As I found I had to remove wires from the plug and put them in another place in the plug. Again take your time! Enjoy the pics! Attached Images __________________ 1984 Chevy Stepside, 4spd granny, 4 1/2 front/6 inch rear drop.

05-24-2007, 12:05 PM	#6
chevysnbuicks Registered User Join Date: May 2007 Location: Friendsville, TN Posts: 27	Re: tach Don't mean to jack ur thread, but does anyone know what is involved in switching to a tach cluster in a '77? __________________ Chevy makes a fine truck, but a really BAD airplane! (haha, long story.) Last edited by chevysnbuicks; 05-24-2007 at 12:05 PM.

05-24-2007, 03:53 PM	#7
Captkaos www.73-87chevytrucks.com Join Date: Dec 1999 Location: Birmingham, AL Posts: 6,935	Re: tach You cannot put a 73-75 dash in anything BUT a 73-75 unless you plan to rewire the whole truck, the circuits are not the same. They use AMPS not volts, you could possibly Fry the whole setup. read the supplied link.. As for swapping to a tach in a 77, If it isn't a 76-77 tach setup, you will need to rewire the harness also. Again, see supplied link. __________________ Chris Lucas 1973 Chevy C-10 1978 GMC Jimmy (2WD) - SOLD 1987 R10 twin turbo LS 1991 R3500 SRW CrewCab 1985 K5 diesel swapped project 1989 K5 2WD conversion w/ Vette susp Project Captkaos Customs 73-87chevytrucks.com

05-24-2007, 06:23 PM	#8
Ivan D. glamoros piece o' lowlife Join Date: Mar 2007 Location: Redford, MI Posts: 1,164	Re: tach I read the article, it don't say much about the '79s - I got a truck with the gauges package, it's got a voltmeter, temp, and pressure (electric, not mechanical). I currently have an aftermarket tach, but I'd like to swap in a OEM tach cluster and move the aftermarket tach to my car. Does anyone know what donor truck I need to pull the tach cluster off? Thanks! __________________ The more I drink, the more I drink, the more I drink... diesel, reg cab, long bed, 4 across the rear, single stack, wooden stakes, and lotsa lights - the Hay Express

05-25-2007, 04:19 AM	#10
Ivan D. glamoros piece o' lowlife Join Date: Mar 2007 Location: Redford, MI Posts: 1,164	Re: tach Cool, thanks, that's what I thought too. And yes, I know I'll need the whole cluster, just wasn't quite sure which exactly whole cluster that is... of course now that I have the time and the money to go to the local U-Pull-It yard the weather's gonna be bad the whole weekend __________________ The more I drink, the more I drink, the more I drink... diesel, reg cab, long bed, 4 across the rear, single stack, wooden stakes, and lotsa lights - the Hay Express

05-25-2007, 05:00 PM	#11
tyjoja Registered User Join Date: Jan 2007 Location: albany oregon Posts: 168	Re: tach Thank you captkaos, that looks like a great article. I was afraid that I had screwed up and got the wrong cluster so I ran out to my 73 and checked my guaged cluster that I had bought and it has a volt guage not amps. so I think I've got the right year. But I still remember thinking that something wasn't right, not all the cluster lights worked and the mech. press. guage didn't work etc. I may have hooked the pressure line into the wrong place on my block. It looked like the harness plug on the back did not have enough wires going to it, several wire spaces missing. I had that thing in and out about 10 times and finally ran out of patience and put the idiot lights back in. But thanks for the link, when motivated I want to try again sometime. thanks bob

05-25-2007, 09:33 PM	#12
Pyrotechnic Registered User Join Date: Feb 2007 Location: Austin, TX Posts: 3,930	Re: tach On the topic of gauge clusters, can I use a 78 Silverado speedometer in a 77 Sierra ? The only difference I see in the clusters is that the oil pressure gauge in the 77 is mechanical and the 78 is electronic.

05-25-2007, 10:42 PM	#13
magnethead 7000 #'s of american IRON Join Date: Dec 2004 Location: north tx Posts: 883	Re: tach the speedometer itself you probably can. Personally i like aftermarket external tach's better, little more sporty ans stil look clean when wires are hidden. On a side topic, where's a good easy to get to wire that i can tap my tach light off of?



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