Please help me with mystery hole in firewall - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mocwon · 03-20-2005, 01:33 AM

It's been about 2-years since I took the beast apart. The pictures I took at the time I took it apart aren't helping. I know one of these two holes in the firewall is for the speeometer cable but I don't know what goes through the other hole. Anyone know??? Thanks

Longhorn Man · 03-20-2005, 01:41 AM

Parking brake i think.

*Shane* · 03-20-2005, 01:43 AM

Parking brake cable goes thru the rectangular hole right under the hole your thinking of Andy ... or at least it was on my cab when I disassembled.

*screamin_c102* · 03-20-2005, 01:44 AM

Top one is speedo and the lower rectangular one is for the parking brake.

I just checked Screamin and I dont have the lower round hole.

must be year specific???

jimfulco · 03-20-2005, 02:17 AM

Clutch rod?

sdkid · 03-20-2005, 03:00 AM

Mine is a '70 c10. The left hole is the speedo cable and the right hole has a grommet with an orange wire through it. I didn't follow the wire.

JimKshortstep4x4 · 03-20-2005, 07:48 AM

The smaller hole is for the speedometer and the larger hole is for the harness that is part of the spark control system.

Jim

Rollie396 · 03-20-2005, 12:08 PM

Found this on the boards.Thanks to whoever took the time to do it!

modifiedGMC · 03-20-2005, 12:43 PM

Here's a pic of my 69 GMC. I marked the holes for you. I hope this helps.

72MARIO · 03-20-2005, 01:44 PM

The hole to the right is a wiring harness for the spark controll and polution controll. I think it's a 72 only thing. I have the wiring harness in a box somwhere I welded up all the unnessary holes in my fire wall.

mr402 · 03-20-2005, 02:18 PM

Right click save.

72ChevyRock · 03-20-2005, 06:47 PM

That is true. I have a 72 and I just yanked that wiring harness out. That hole is for the engine harness that is used for the automatic idle control/temperature sensor/polution control. I rolled mine up to sleep in the grave with the other useless parts.

mocwon · 03-20-2005, 07:53 PM

Yes, that's a great post but if you look close the hole I mentioned is missing. The folks that posted it's for the spark control and pollution control are correct after some other checking. Looks like I'll use it for the mechanical oil pressure gauge since I welded that hole up.

Thanks for the help folks!!!

Quote:

Originally Posted by Rollie396

Found this on the boards.Thanks to whoever took the time to do it!

72MARIO · 03-20-2005, 08:03 PM

Quote:

I rolled mine up to sleep in the grave with the other useless parts

Me too. That pile was actually quite big. I just started thining the pile out this week. I dont want to be a pack rat.......Well not yet.

shifty · 03-21-2005, 12:27 AM

I was about to say it was for choke, but my speedo and choke are sitting directly above each other :thinking:

conman · 03-21-2005, 10:02 PM

I just pulled the wires out of my 72. The two holes on mine are as follows:

Top left hole speedo cable.

Bottom right, a wiring harness, some wires went near the heater core, and
a couple continued on down near the starter.

Hope that helps.

03-20-2005, 01:33 AM	#1
mocwon Keep On Truckin' Join Date: Mar 2003 Location: Buda, Texas Posts: 1,354	Please help me with mystery hole in firewall It's been about 2-years since I took the beast apart. The pictures I took at the time I took it apart aren't helping. I know one of these two holes in the firewall is for the speeometer cable but I don't know what goes through the other hole. Anyone know??? Thanks Attached Images __________________ Just Passin' Thru Some projects are like herding cats; others are like putting out fires; this one was like herding cats on fire.....

03-20-2005, 01:44 AM	#4
screamin_c102 Account Suspended Join Date: Feb 2005 Location: Yoncalla Oregon Posts: 775	Top one is speedo and the lower rectangular one is for the parking brake. I just checked Screamin and I dont have the lower round hole. must be year specific??? Last edited by screamin_c102; 03-20-2005 at 01:48 AM.

03-20-2005, 03:00 AM	#6
sdkid Registered User Join Date: Sep 2004 Location: Pierre SD Posts: 1,533	Mine is a '70 c10. The left hole is the speedo cable and the right hole has a grommet with an orange wire through it. I didn't follow the wire. __________________ I think the world needs a drink... Help somebody...If you can....VanZant We're not wrong, we're not sorry, and its probably gonna happen again. That's the truth about men. Tracy Byrd Member# 13924 '70 c10, 350/350 '68 c10 250/4spd '68 c10 no eng/trans fac ps/pb/ac/at (future father/sons project) '48 Chevy Loadmaster

03-20-2005, 12:08 PM	#8
Rollie396 someday it will be done! Join Date: Sep 2004 Location: Lloydminster,AB. Canada Posts: 1,620	Found this on the boards.Thanks to whoever took the time to do it! Attached Images __________________ '72 C-10 Proud owner of a million new and used pieces that used to be and will once again be(god willing) a testament to the term "they don't build em like that anymore. '80 LWB 2wd beater '67 GMC long fleet (cab donor) '66 long step (parked till it's turn comes around) '65 short step (parts truck that will donate it's bed and possibly frame to the '66) '06 Grand Prix wife's car (she hardly lets me touch it) my pics

03-20-2005, 12:43 PM	#9
modifiedGMC Registered User Join Date: Oct 2004 Location: Walker Co. Alabama Posts: 474	Here's a pic of my 69 GMC. I marked the holes for you. I hope this helps. __________________ If it don't fit, force it,...If it still don't fit , modify it 'till it does fit !!!

03-20-2005, 01:41 AM	#2
Longhorn Man its all about the +6 inches Join Date: Jan 2001 Location: Hilliard Ohio Posts: 2,693	Parking brake i think.

03-20-2005, 01:43 AM	#3
Shane Account Suspended Join Date: Jun 2000 Location: over yonder Posts: 14,270	Parking brake cable goes thru the rectangular hole right under the hole your thinking of Andy ... or at least it was on my cab when I disassembled.

03-20-2005, 02:17 AM	#5
jimfulco Registered User Join Date: May 2003 Location: Shreveport LA Posts: 3,170	Clutch rod?

03-20-2005, 07:48 AM	#7
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	The smaller hole is for the speedometer and the larger hole is for the harness that is part of the spark control system. Jim

03-20-2005, 01:44 PM	#10
72MARIO Registered User Join Date: Nov 2000 Location: Huntsville Ontario Canada Posts: 4,052	The hole to the right is a wiring harness for the spark controll and polution controll. I think it's a 72 only thing. I have the wiring harness in a box somwhere I welded up all the unnessary holes in my fire wall. __________________ 1968 Suburban numbers matching all original truck now equipped with 6.0/4L80 on Accuair http://67-72chevytrucks.com/vboard/s...d.php?t=625017 1967 C/20 6.0/4L80 Roofing Truck 1990 V2500 Suburban "Plow Truck" 2005 TAHOE DD

03-20-2005, 02:18 PM	#11
mr402 Registered User Join Date: Jan 2004 Location: Elmira, Oregon Posts: 449	Right click save.

03-20-2005, 06:47 PM	#12
72ChevyRock Registered User Join Date: Jul 2004 Location: Albuquerque, NM Posts: 55	That is true. I have a 72 and I just yanked that wiring harness out. That hole is for the engine harness that is used for the automatic idle control/temperature sensor/polution control. I rolled mine up to sleep in the grave with the other useless parts. __________________ Primer Gray 72 LWB w/a 307

03-21-2005, 12:27 AM	#15
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	I was about to say it was for choke, but my speedo and choke are sitting directly above each other :thinking: __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

03-21-2005, 10:02 PM	#16
conman Registered User Join Date: Jan 2002 Location: Fayette, Alabama Posts: 155	I just pulled the wires out of my 72. The two holes on mine are as follows: Top left hole speedo cable. Bottom right, a wiring harness, some wires went near the heater core, and a couple continued on down near the starter. Hope that helps. __________________ Fayette Alabama



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