Firewall.....What are these holes for? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

MisterE72 · 07-30-2009, 01:53 PM

Greetings folks. I'm getting ready to fill in the firewall but don't have any idea what these holes are for and if they should be filled in. I'm running a carburated SBC mated to a 700R4, power brakes, and an aftermarket A/C. Thank you for any help you can provide. MisterE

gcburdic · 07-30-2009, 02:27 PM

I couldn't find a pic that soemone did showing what all those holes are for, but I did my best to label some of them for you....what year is the cab??

MisterE72 · 07-30-2009, 03:27 PM

Quote:

Originally Posted by gcburdic

I couldn't find a pic that soemone did showing what all those holes are for, but I did my best to label some of them for you....what year is the cab??

Thanks for the help. The truck is a 72 custom deluxe. Any idea what the two bigger holes on pic 1 are for?

gcburdic · 07-30-2009, 04:01 PM

Not sure what they are for....but I did remember in the 2nd photo the one I didn't mark is for the intermediate wiring harness that runs from the firewall to the rear cross sill for the rear tail light connections...sorry....i know someone will post up a pic of that firewall...I'll keep looking too!!!

justin26 · 07-30-2009, 04:03 PM

the two bigger holes in pic one are left hole if foe the cable from the heater controls it opens the flap on the outside heater box for the ac and the other is for the wires the go the the fan motor, graound on the fan motor and the other i believe goes the ac compressor but im not for sure i cant find it on a wiring diagram anywhere longhorn would probaly know hope this helps

big_al_71 · 07-30-2009, 05:41 PM

Sr. E if you want a clean firewall only leave the holes I left, if you need to you can always redrill....

Small block
Classic auto air
Nothing else on the firewall but the harness...

Dynomutt · 07-30-2009, 06:12 PM

Here's that drawing. The holes on the passenger side are for A/C control hoses and wires.

gcburdic · 07-30-2009, 06:25 PM

yep....that's the one I was talking about!!!....Thanks Dynamutt

**Jurassic-1** · 07-30-2009, 08:51 PM

The holes in pic.1 are. Left hole Control cable fir the heater. The hole on the right is for the Vacuum lines to open the heat control valve and also the line going to the vac. Ball it also allows for a line back into the cab to feed the vac. switch on the ac. control.

MisterE72 · 07-31-2009, 11:30 AM

Are most folks replacing the firewall insulator pad? I'd like to fill in the little fastner holes for that too. I imagine the insulator pad can be glued on using 3M contact cement instead of the fastners.

gcburdic · 07-31-2009, 12:19 PM

Quote:

Originally Posted by MisterE72

Are most folks replacing the firewall insulator pad? I'd like to fill in the little fastner holes for that too. I imagine the insulator pad can be glued on using 3M contact cement instead of the fastners.

Yep...you can fill those holes....just use dyna-mat, fat-mat, maybe lizard skin or whatvever you want to insulate the cab!!!

MisterE72 · 07-31-2009, 08:48 PM

My neighbor Isaiah and I got started in it today. More to come later.

elf w/capital T · 11-11-2013, 08:43 PM

Old thread, found using search! Haha how neat... thanks for everyone here btw!

07-30-2009, 01:53 PM	#1
MisterE72 Keep Your Nose Clean Join Date: Dec 2006 Location: California Posts: 496	Firewall.....What are these holes for? Greetings folks. I'm getting ready to fill in the firewall but don't have any idea what these holes are for and if they should be filled in. I'm running a carburated SBC mated to a 700R4, power brakes, and an aftermarket A/C. Thank you for any help you can provide. MisterE Attached Images

07-30-2009, 02:27 PM	#2
gcburdic Restoration Virgin! Join Date: Jan 2008 Location: Huntersville, NC Posts: 8,298	Re: Firewall.....What are these holes for? I couldn't find a pic that soemone did showing what all those holes are for, but I did my best to label some of them for you....what year is the cab?? Attached Images __________________ Geoff with a G 1968 Chevy C10 SWB The Mistress 1972 Custom Deluxe C20 Suburban A Suburban Named Isabella 1966 Ford Mustang Mama's High School Graduation Present Last edited by gcburdic; 07-30-2009 at 02:28 PM.

07-30-2009, 04:01 PM	#4
gcburdic Restoration Virgin! Join Date: Jan 2008 Location: Huntersville, NC Posts: 8,298	Re: Firewall.....What are these holes for? Not sure what they are for....but I did remember in the 2nd photo the one I didn't mark is for the intermediate wiring harness that runs from the firewall to the rear cross sill for the rear tail light connections...sorry....i know someone will post up a pic of that firewall...I'll keep looking too!!! __________________ Geoff with a G 1968 Chevy C10 SWB The Mistress 1972 Custom Deluxe C20 Suburban A Suburban Named Isabella 1966 Ford Mustang Mama's High School Graduation Present

07-30-2009, 04:03 PM	#5
justin26 Registered User Join Date: Feb 2009 Location: hot springs arkansas Posts: 101	Re: Firewall.....What are these holes for? the two bigger holes in pic one are left hole if foe the cable from the heater controls it opens the flap on the outside heater box for the ac and the other is for the wires the go the the fan motor, graound on the fan motor and the other i believe goes the ac compressor but im not for sure i cant find it on a wiring diagram anywhere longhorn would probaly know hope this helps

07-30-2009, 05:41 PM	#6
big_al_71 Registered User Join Date: Jun 2008 Location: South Florida Posts: 11,375	Re: Firewall.....What are these holes for? Sr. E if you want a clean firewall only leave the holes I left, if you need to you can always redrill.... Small block Classic auto air Nothing else on the firewall but the harness... Attached Images __________________ Get your facts first, and then you can distort them as much as you please!!!!!. Sylvester's build thread >>>http://67-72chevytrucks.com/vboard/s...ht=big+rebuild

07-30-2009, 06:12 PM	#7
Dynomutt Registered User Join Date: Mar 2009 Location: North Texas Posts: 440	Re: Firewall.....What are these holes for? Here's that drawing. The holes on the passenger side are for A/C control hoses and wires. Attached Images __________________ MARQ Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=446194 Last edited by Dynomutt; 07-30-2009 at 06:19 PM.

07-30-2009, 06:25 PM	#8
gcburdic Restoration Virgin! Join Date: Jan 2008 Location: Huntersville, NC Posts: 8,298	Re: Firewall.....What are these holes for? yep....that's the one I was talking about!!!....Thanks Dynamutt __________________ Geoff with a G 1968 Chevy C10 SWB The Mistress 1972 Custom Deluxe C20 Suburban A Suburban Named Isabella 1966 Ford Mustang Mama's High School Graduation Present

07-30-2009, 08:51 PM	#9
Jurassic-1 Registered User Join Date: Jul 2007 Location: New River Arizona Posts: 1,180	Re: Firewall.....What are these holes for? The holes in pic.1 are. Left hole Control cable fir the heater. The hole on the right is for the Vacuum lines to open the heat control valve and also the line going to the vac. Ball it also allows for a line back into the cab to feed the vac. switch on the ac. control.

07-31-2009, 11:30 AM	#10
MisterE72 Keep Your Nose Clean Join Date: Dec 2006 Location: California Posts: 496	Re: Firewall.....What are these holes for? Are most folks replacing the firewall insulator pad? I'd like to fill in the little fastner holes for that too. I imagine the insulator pad can be glued on using 3M contact cement instead of the fastners.

07-31-2009, 08:48 PM	#12
MisterE72 Keep Your Nose Clean Join Date: Dec 2006 Location: California Posts: 496	Re: Firewall.....What are these holes for? My neighbor Isaiah and I got started in it today. More to come later. Attached Images

11-11-2013, 08:43 PM	#13
elf w/capital T Registered User Join Date: Feb 2011 Location: North Carolina Posts: 993	Re: Firewall.....What are these holes for? Old thread, found using search! Haha how neat... thanks for everyone here btw!



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