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

canso · 03-05-2003, 01:37 AM

I am installing a tach dash in my 72. I am wondering what hole on the fire wall did they run the wire through to the distributor. There are two holes with plugs above the hole that the throttle cable runs through I suspect it is one of these. Thanks for the help.

*Gee_Emm* · 03-06-2003, 07:29 PM

When I installed mine it came as a kit and it showed me which hole it is. I had to drill it, the place where it is supposed to go has a little dimple in the metal. I will look at the instructions tommorow, PM me if a couple days go by and I forget.

gregsplace · 03-07-2003, 12:07 AM

my 71 cheyenne that I had, had a factory tach, the wire went threw a hole above the speedo. cable hole on it. If you're not concerned about originality, run it threw one of the washer tube hole grommet holes

JimKshortstep4x4 · 03-07-2003, 09:53 AM

We have a couple of trucks with the tachs originally installed and the wire to the coil feeds through the fire wall close to the fuse panel. The 3/4" hole is centered by the panel and is real close to it (on the left fender side). The rubber grommet on your wire fits into the 3/4" hole. The wire is routed up from the hole into the channel wire holder and across to just above the
distributor and then down to the coil.

The assembly manual instructions show this also.

If you need a pic, we have the Burb firewall completely bare, but I am sure that there is a dimple in your firewall at the location that I described.

Any questions?

Jim

canso · 03-07-2003, 02:16 PM

I do want to run the wire in the original spot. I have the harness with the 3/4 grommet. Does anyone have a picture of the spot. Thanks

*Gee_Emm* · 03-07-2003, 03:51 PM

As per the instructions that came with my tach kit.

To have the wire in the factory postion, left of the fusebox there are 4 dimples, the 2nd one from the top drill a 3/4" hole.

canso · 03-07-2003, 09:51 PM

I have counted the dimples between the fender and the fuse block, there are five in a verticle row. If I put it in the second hole from the top the bracket that goes from the booster to the firewall is in the way.

*Gee_Emm* · 03-08-2003, 11:56 AM

Here lets see if my crude attempt at enlarging works, its the red wire.

Dan72cst · 03-08-2003, 01:58 PM

Here's my original 72 blazer

JimKshortstep4x4 · 03-08-2003, 03:38 PM

Here is a pic of the firewall that has the original hole drilled into it
for the tach wire. The 3/4" hole is in the same location as Dan72cst's and it is the location that the assembly manual shows.

Jim

*Gee_Emm* · 03-08-2003, 03:41 PM

Way to out do all of us with that pic Jim

:p

Dan72cst · 03-08-2003, 05:09 PM

sheeesh no kidding nice pic

JimKshortstep4x4 · 03-09-2003, 05:33 AM

Digital cameras are great!

We happen to have a couple of projects going in different stages
and this shot is of the 72 Burb firewall that we have been working on forever. Burb bodies are huge and take a lot of time.

Jim

*Gee_Emm* · 03-09-2003, 01:41 PM

I was wondering why I could see light when looking through the fusebox hole :p

It makes more sense now

**lolife99** · 02-20-2011, 02:18 PM

Nate,... I found this old thread for you.
There is so much confusion on this subject.
The 67-68 firewalls are different,... so I guess you have to address 69-72 trucks only.

**lolife99** · 02-20-2011, 02:22 PM

I also have this random picture I took of my 1-owner '70 stepside.
I don't remember what the red wire went to, (maybe an aftermarket gauge),... but the rubber grommet looks factory.
Also,... this truck had NO factory tach or gauges.

72BlckButy · 02-20-2011, 04:20 PM

Thanks Keith... We'll see what pops up.

Any additional insight out there?

**LockDoc** · 02-20-2011, 04:49 PM

-
Here are two different ones. the first one is a '67-'68 six cyl and i think one of the cables shown is for a cable driven tach. The second one is '71 six & V-8

LockDoc

72BlckButy · 02-20-2011, 04:55 PM

Great post Leon!

From the diagrams you posted it shows that Keith was spot on when discussing two different opening locations for the 67-68 and the 69-72. Should take the guess work out now.

03-05-2003, 01:37 AM	#1
canso Registered User Join Date: Jun 2001 Posts: 92	tach wire ? I am installing a tach dash in my 72. I am wondering what hole on the fire wall did they run the wire through to the distributor. There are two holes with plugs above the hole that the throttle cable runs through I suspect it is one of these. Thanks for the help.

03-07-2003, 12:07 AM	#3
gregsplace Senior Member Join Date: Dec 2000 Location: Colwich,Kansas Posts: 713	my 71 cheyenne that I had, had a factory tach, the wire went threw a hole above the speedo. cable hole on it. If you're not concerned about originality, run it threw one of the washer tube hole grommet holes __________________ 67 3/4 4x4 402,a/t,flat bed 98 GMC Sierra swb daily driver 87 burb parting out. 68 1/2 chevy, 350/350, 71 gmc frame, kid's beater 69 1ton 396-4sp, dump 69 swb stepside 396/400th current frameup 67 swb 454/400th rebuilding now, oldest boy just rolled it 99,HD, Road King Classic Colwich Ks

03-08-2003, 01:58 PM	#9
Dan72cst Registered User Join Date: Feb 2001 Location: Lake Stevens,WA 98258 North of Seattle Posts: 833	Here's my original 72 blazer Attached Images __________________ Marysville, WA (Dan72cst@hotmail.com) 72 4wd Blazer CST 350/350 72 4wd Chevy LWB 350/350 68 2wd Chevy LWB 327/400

03-08-2003, 03:38 PM	#10
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Here is a pic of the firewall that has the original hole drilled into it for the tach wire. The 3/4" hole is in the same location as Dan72cst's and it is the location that the assembly manual shows. Jim Attached Images

03-08-2003, 05:09 PM	#12
Dan72cst Registered User Join Date: Feb 2001 Location: Lake Stevens,WA 98258 North of Seattle Posts: 833	sheeesh no kidding nice pic __________________ Marysville, WA (Dan72cst@hotmail.com) 72 4wd Blazer CST 350/350 72 4wd Chevy LWB 350/350 68 2wd Chevy LWB 327/400

03-06-2003, 07:29 PM	#2
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	When I installed mine it came as a kit and it showed me which hole it is. I had to drill it, the place where it is supposed to go has a little dimple in the metal. I will look at the instructions tommorow, PM me if a couple days go by and I forget.

03-07-2003, 09:53 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	We have a couple of trucks with the tachs originally installed and the wire to the coil feeds through the fire wall close to the fuse panel. The 3/4" hole is centered by the panel and is real close to it (on the left fender side). The rubber grommet on your wire fits into the 3/4" hole. The wire is routed up from the hole into the channel wire holder and across to just above the distributor and then down to the coil. The assembly manual instructions show this also. If you need a pic, we have the Burb firewall completely bare, but I am sure that there is a dimple in your firewall at the location that I described. Any questions? Jim

03-07-2003, 02:16 PM	#5
canso Registered User Join Date: Jun 2001 Posts: 92	I do want to run the wire in the original spot. I have the harness with the 3/4 grommet. Does anyone have a picture of the spot. Thanks

03-07-2003, 03:51 PM	#6
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	As per the instructions that came with my tach kit. To have the wire in the factory postion, left of the fusebox there are 4 dimples, the 2nd one from the top drill a 3/4" hole.

03-07-2003, 09:51 PM	#7
canso Registered User Join Date: Jun 2001 Posts: 92	I have counted the dimples between the fender and the fuse block, there are five in a verticle row. If I put it in the second hole from the top the bracket that goes from the booster to the firewall is in the way.

03-08-2003, 11:56 AM	#8
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	Here lets see if my crude attempt at enlarging works, its the red wire.

03-08-2003, 03:41 PM	#11
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	Way to out do all of us with that pic Jim :p

03-09-2003, 05:33 AM	#13
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	Digital cameras are great! We happen to have a couple of projects going in different stages and this shot is of the 72 Burb firewall that we have been working on forever. Burb bodies are huge and take a lot of time. Jim

03-09-2003, 01:41 PM	#14
Gee_Emm Account Suspended Join Date: Sep 2000 Posts: 4,002	I was wondering why I could see light when looking through the fusebox hole :p It makes more sense now

02-20-2011, 02:18 PM	#15
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,691	Re: tach wire ? Nate,... I found this old thread for you. There is so much confusion on this subject. The 67-68 firewalls are different,... so I guess you have to address 69-72 trucks only. __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823 Last edited by lolife99; 02-20-2011 at 02:26 PM.



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02-20-2011, 02:22 PM	#16
lolife99 67-72 parts collector,… Join Date: Nov 2002 Location: Mid-MO Posts: 22,691	Re: tach wire ? I also have this random picture I took of my 1-owner '70 stepside. I don't remember what the red wire went to, (maybe an aftermarket gauge),... but the rubber grommet looks factory. Also,... this truck had NO factory tach or gauges. Attached Images __________________ Keith Convert to disc brakes. http://67-72chevytrucks.com/vboard/s...d.php?t=444823

02-20-2011, 04:20 PM	#17
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: tach wire ? Thanks Keith... We'll see what pops up. Any additional insight out there? __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package)

02-20-2011, 04:49 PM	#18
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,402	Re: tach wire ? - Here are two different ones. the first one is a '67-'68 six cyl and i think one of the cables shown is for a cable driven tach. The second one is '71 six & V-8 LockDoc Attached Images __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 - Last edited by LockDoc; 02-20-2011 at 05:09 PM.

02-20-2011, 04:55 PM	#19
72BlckButy Tot Roddin' Join Date: Apr 2005 Location: Mid-MO Posts: 24,461	Re: tach wire ? Great post Leon! From the diagrams you posted it shows that Keith was spot on when discussing two different opening locations for the 67-68 and the 69-72. Should take the guess work out now. __________________ -Nate 1969 CST SWB - Project Blank Slate (4.5/6" ECE Static Drop, 6-lug disc brake upgrade (manual), Billet Specialties Vintec 20x8.5 255/40 (F) 20x10 295/40 (R), 250 I-6) 1960 AMF Skylark - Tot Roddin' (Lowered with custom frame; soon to include custom push bar and interior) 2008 Silverado CrewCab 1LT (5.3L, 3:73, 4x4, LT1, Z-71, Towing Package) Last edited by 72BlckButy; 02-20-2011 at 04:56 PM.

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