The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 01-18-2012, 11:52 AM   #1
sixshooter798
Desert Rat
 
sixshooter798's Avatar
 
Join Date: Jul 2010
Location: Mojave Desert
Posts: 169
Large to small fuel gauge

I'm sure this has been posted 800 million times, but the search engine didn't yield promising results.

I'm going to swap out my gauge cluster for one with a tach in it, so I'll be going from the large fuel gauge to the small one. Will I need to re-pin the plug that goes into the back of the cluster?
sixshooter798 is offline   Reply With Quote
Old 01-18-2012, 12:23 PM   #2
ray_mcavoy
Registered User
 
Join Date: Nov 2009
Location: Sherman, ME
Posts: 2,366
Re: Large to small fuel gauge

Hi sixshooter798,

I didn't have to re-pin the cluster plug when I swapped a tach cluster into dad's 77. His truck already had the factory gauge package (minus the tach) so all I had to do was add the separate harness for the tach.

Before making the swap, I looked at the factory wiring diagrams and it looks like they already took the fuel gauge difference into account. The cluster plug already has two terminals each wired up to the fuel gauge & brake warning light. One pair of terminals is unused by the non-tach gauge cluster while the other pair is unused by the tach cluster.

Note that if you're dealing with a truck that had an idiot light cluster from the factory, you will have to re-pin the connector (and maybe make some wiring changes) to install a full-gauge cluster.

And you might have to do some re-pinning and/or other changes if you're installing a tach cluster out of a medium duty truck. The ones with the small fuel gauge directly below the tach.

Wiring changes will also be necessary if you're using a cluster from a different year range than your truck. For example, 73-75 = ammeter, 76-up = voltmeter. And 73-77 = mechanical oil gauge, 78-up = electric oil gauge.
ray_mcavoy is offline   Reply With Quote
Old 01-19-2012, 12:55 AM   #3
sixshooter798
Desert Rat
 
sixshooter798's Avatar
 
Join Date: Jul 2010
Location: Mojave Desert
Posts: 169
Re: Large to small fuel gauge

Cool thanks for the info!
sixshooter798 is offline   Reply With Quote
Old 01-19-2012, 11:29 AM   #4
motornut
78K & 79C Jimmys
 
motornut's Avatar
 
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
Re: Large to small fuel gauge

i changed from idiots to gauges/tach
just a couple of wires for yours
notes in my 78 jimmy tread below
see notes on the power and adding grounds.....
i powered my tach from the cluster power
__________________
John
1978 GMCJimmy4X4-350/203
1979 GMCJimmy4X2-305/350
motornut is offline   Reply With Quote
Old 01-19-2012, 12:17 PM   #5
Evil Trailblazer SS
Big Gulps Huh? Whelp...
 
Evil Trailblazer SS's Avatar
 
Join Date: Apr 2010
Location: Reno, NV
Posts: 410
Re: Large to small fuel gauge

As long as your truck had all the small gauges (Oil Pressure, Water Temp, Voltage) your wiring will not have to be re-pinned...

Motornut has a great write-up. The tach wiring harness is simple to wire in, tapp the 12v for the tach gauge off one of the pink/black ingtion 12v wires in the existing cluster harness. Tap the ground to one of the black grounds in the same cluster wiring harness. Run a wire from the Tach Signal on the tach gauge to the distributor. All HEI distributors have a terminal marked "Tach" and all external coils have a wire from the gray plug (Small white wire in same plug as large pink coil wire).
__________________
"The Ghost II" - 1987 V30 CC, 14-BFF (2nd Design Heavy Ribbed HD) SRW Conversion, 454/4L80E/205, 6" Springs, 35" Toyo MT's on 17" Classic II's, Full Audio System, Lot of Other Goodies!
Evil Trailblazer SS is offline   Reply With Quote
Old 01-19-2012, 03:04 PM   #6
texastruckjunky
Registered User
 
texastruckjunky's Avatar
 
Join Date: May 2009
Location: San Antonio,Texas
Posts: 220
Re: Large to small fuel gauge

You see thats why this site is so bad A**, so much usefull information. Thats good to know, now i can put my tack in my blazer. So the tack cluster out of a 78 blazer will work in my 79 blazer? I got every thing even the engine wireing harness.
__________________
Life is to short to drive anything else
texastruckjunky is offline   Reply With Quote
Old 01-19-2012, 06:24 PM   #7
motornut
78K & 79C Jimmys
 
motornut's Avatar
 
Join Date: Nov 2009
Location: Ottawa Ont CANADA
Posts: 7,901
Re: Large to small fuel gauge

Quote:
Originally Posted by texastruckjunky View Post
You see thats why this site is so bad A**, so much usefull information. Thats good to know, now i can put my tack in my blazer. So the tack cluster out of a 78 blazer will work in my 79 blazer? I got every thing even the engine wireing harness.
yup it will...good luck,have you considered painting the inside it sure helped mine
__________________
John
1978 GMCJimmy4X4-350/203
1979 GMCJimmy4X2-305/350
motornut is offline   Reply With Quote
Old 01-19-2012, 10:57 PM   #8
texastruckjunky
Registered User
 
texastruckjunky's Avatar
 
Join Date: May 2009
Location: San Antonio,Texas
Posts: 220
Re: Large to small fuel gauge

Yea, thats the plan. I'll get some pics when i get it done, to show everybody how it turns out.
__________________
Life is to short to drive anything else
texastruckjunky is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:45 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com