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73-87 Chevy _ GMC Trucks => 73-87 Chevy & GMC Trucks => Topic started by: gold84gmc on August 06, 2007, 01:33:18 pm

Title: aftermarket tach
Post by: gold84gmc on August 06, 2007, 01:33:18 pm

hi, i have an 84 gmc 2500 2wd with the 5.7L 4bbl engine...im trying to hook up an aftermarket tach. it says to hook up one of the wires of the tach to the distributor, on the connection marked "tach". but i looked and there is already a white wire plugged into there but the truck dosnt have a factory tach. so can i unplug that wire and plug in the one for the tach? or will it screw up something or what? and does anyone know what that white wire is for or where it goes? thanks.

Title: Re: aftermarket tach
Post by: gold84gmc on August 07, 2007, 11:10:07 am

anyone have any ideas? or should i just try it.

Title: Re: aftermarket tach
Post by: Lt.Del on August 07, 2007, 11:24:42 am

I am assuming you have an HEI distributor.  Your white wire is not in the "Tach" slot, it is in the "coil" slot.  The green wire from the tach goes to the terminal labeled "tach" on distr.cap. 

If you ever replaced the coil inside the distr. cap, you'll see what I'm speaking of. If memory serves me, you will see a red wire and a white wire from the coil.  The only wire you see plugged into the bottom side of that area is the red wire w/ white clip.  That is the ignition wire.

(http://www.delbridge.net/dii.jpg)

Title: Re: aftermarket tach
Post by: DirtyLittleSecret on August 07, 2007, 11:28:39 am

And if the wires are pink/purple with a light lemon twist and sugared rim? (just jokin')

Title: Re: aftermarket tach
Post by: 123 pugsy on August 07, 2007, 11:36:24 am

 

Quote from: gold84gmc on August 06, 2007, 01:33:18 pm

hi, i have an 84 gmc 2500 2wd with the 5.7L 4bbl engine...im trying to hook up an aftermarket tach. it says to hook up one of the wires of the tach to the distributor, on the connection marked "tach". but i looked and there is already a white wire plugged into there but the truck dosnt have a factory tach. so can i unplug that wire and plug in the one for the tach? or will it screw up something or what? and does anyone know what that white wire is for or where it goes? thanks.

Pull it out and try it. ;)

Title: Re: aftermarket tach
Post by: VileZambonie on August 07, 2007, 02:51:45 pm

Do you have Vacuum advance or HEI with ESC?

Title: Re: aftermarket tach
Post by: gold84gmc on August 07, 2007, 02:54:47 pm

here is some pics of what im talkin about. the white wire that plugs in to the "tach" slot

Title: Re: aftermarket tach
Post by: gold84gmc on August 07, 2007, 02:55:44 pm

as far as i know its vacum, because its a 1984

Title: Re: aftermarket tach
Post by: VileZambonie on August 07, 2007, 08:36:05 pm

Is there a 4 wire plug connected to the distributor?

Title: Re: aftermarket tach
Post by: gold84gmc on August 07, 2007, 09:23:18 pm

yea there is one big plug, not sure if its 3 or 4 wires though..i'd have to look.

Title: Re: aftermarket tach
Post by: VileZambonie on August 08, 2007, 10:00:29 am

Then you need that wire. Just splice into it.

Title: Re: aftermarket tach
Post by: gold84gmc on August 08, 2007, 02:56:37 pm

alright, thanks