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70 B body tach hole

Posted By: DPelletier

70 B body tach hole - 01/31/10 04:46 AM

There was a thread here a while back, but I guess I forgot to print out the info sooooo:

Can anybody tell me the size and location of the hole in the firewall for the factory grommet used on a 70 B body with a tach? Pics?

I think it's right next to the bulkhead wiring block, but....

Thanks

Dave
Posted By: 70gtx440dana

Re: 70 B body tach hole - 02/01/10 03:21 PM

Here is a picture....not sure on the size!

Attached picture 5774106-70chargertachwiringpicture.jpg
Posted By: DPelletier

Re: 70 B body tach hole - 02/01/10 04:22 PM

Thanks a bunch!

hmmm, not where I thought it'd be; is it a factory tach car? What is the cable directly opposite the firewall bulkhead connector?

Cheers,
Dave
Posted By: Paul

Re: 70 B body tach hole - 02/01/10 04:49 PM

I added a factory tach to my Road Runner many years ago. I had aquired an original tach harness, and used a set of calipers to measure the narrow part of grommet then bought a hole saw at the local hardware store to match. I don't remember the exact size, but 1/2" comes to mind. It was a common size and the grommet fit perfectly.
Posted By: DPelletier

Re: 70 B body tach hole - 02/01/10 06:54 PM

Thanks Paul; was it in the same location as the one in the picture above?

Dave
Posted By: 70gtx440dana

Re: 70 B body tach hole - 02/01/10 08:49 PM

Blue and black wires next to gray tach wire are for the headlight door system on a 70 Charger. I am not sure about the other cable/wire you are questioning without having a look underhood.
Posted By: RT03

Re: 70 B body tach hole - 02/02/10 05:15 AM

This is where the tach hole is drilled on my 70 GTX. It's a factory tach car. The hole diameter is about .830".

Attached picture 5776166-DSC01924.JPG
Posted By: DPelletier

Re: 70 B body tach hole - 02/02/10 04:10 PM

Ahhhh; that's where I thought it should go as opposed to the grey car pictured above.....

Thanks!
Dave
Posted By: 70gtx440dana

Re: 70 B body tach hole - 02/02/10 05:19 PM

Dave,

Here is another picture of a tach wire. It only adds more confusion. I guess I would like to see a few more unmolested cars to confirm.

Attached picture 5776881-hemienginepic.jpg
Posted By: rocketresto

Re: 70 B body tach hole - 02/02/10 05:28 PM

Quote:

This is where the tach hole is drilled on my 70 GTX. It's a factory tach car. The hole diameter is about .830".


I currently have two Super Bees in the shop, a 68 and a 70, both are original tach car and both have holes in the same place as your GTX.
Mike
Posted By: DPelletier

Re: 70 B body tach hole - 02/02/10 06:15 PM



Well, we have 3 different locations listed but three cars which people have stated are original tach cars have them in the same spot as the pic of the '70 GTX, so that location is in the lead so far!

Thanks guys; if anyone has any more info or pics; lets see 'em!

the holesaw is coming out in the next couple of days!

Dave
Posted By: meepmeep70

Re: 70 B body tach hole - 02/02/10 06:19 PM

curious
Posted By: 1_WILD_RT

Re: 70 B body tach hole - 02/02/10 06:35 PM

Quote:



Well, we have 3 different locations listed but three cars which people have stated are original tach cars have them in the same spot as the pic of the '70 GTX, so that location is in the lead so far!

Thanks guys; if anyone has any more info or pics; lets see 'em!

the holesaw is coming out in the next couple of days!

Dave



Add another.. Coded for tach...

Attached picture 5777055-firewall.jpg
Posted By: 6bblgt

Re: 70 B body tach hole - 02/02/10 06:56 PM

Here's my February '70 LA built GTX - original tach hole.

Attached picture 5777089-1970GTXtachhole.JPG
Posted By: 1_WILD_RT

Re: 70 B body tach hole - 02/02/10 07:01 PM

The evidence is mounting...
Posted By: DPelletier

Re: 70 B body tach hole - 02/02/10 08:30 PM

Yeah, I agree: I'm just about ready to declare a winner!

Thank you to everyone who posted!



Dave
Posted By: sixbbl69

Re: 70 B body tach hole - 02/02/10 11:57 PM

tach hole diameter 13/16"
Posted By: DPelletier

Re: 70 B body tach hole - 02/03/10 12:01 AM

Thank you.

Dave
Posted By: 70BIRD

Re: 70 B body tach hole - 05/12/10 05:05 PM

This thread came to mind as I'm installing the wiring in my car...I have a factory tach (70RR) and and I have the hole between the bulkhead and the master cylinder as shown in some of the pics above so that's no problem.

What I'm confused about is in the new dash harness I have there are the black (w/red tracer)and blue (w/yellow tracer) wires that are fed thru a large conical shaped rubber grommet that someone above states is for the headlamps on a 70 Charger.

So on my car are these wires are just left to hang under the dash unused?

Thanks,

Paul
Posted By: 70gtx440dana

Re: 70 B body tach hole - 05/12/10 09:45 PM

These wires are for 70 Charger only. They run the headlight motor to open the doors. You will not need them on a RR. New harness must be generic. I would tape up the connector and even possibly tape this entire pigtail to your harness under dash.
Posted By: MrNormsTA

Re: 70 B body tach hole - 05/12/10 09:59 PM

When adding a tach on a non tach car, I would always drill a small hole in one of the extra spots on one of the bulk head connectors and pass a wire thru.

I really didn't care about the hole, but figured some purist might not like it down the road, so why do it.
Posted By: Hemiruss

Re: 70 B body tach hole - 05/12/10 10:17 PM

Dave the problem is your car is metric and is in the other side,It's a Canadian Thind..........lol lol lol...I thought you'd get a kick out of it from our past post exchanges......lolololololllool


Russ....it's the big one in the middle....

Attached picture 5978897-100_1474.JPG
Posted By: b54406barrel

Re: 70 B body tach hole - 05/12/10 10:27 PM

Quote:

I really didn't care about the hole, but figured some purist might not like it down the road, so why do it.



Years ago I had a wrecked 69 Charger dash & put the tach/clock in my 6bbl rr as it didn't have either. Once I found out how crappy (this was in the 70's) it was & hard to read, I took it out. Glad I didn't drill that hole!
Posted By: 70BIRD

Re: 70 B body tach hole - 05/13/10 01:11 AM

Quote:

These wires are for 70 Charger only. They run the headlight motor to open the doors. You will not need them on a RR. New harness must be generic. I would tape up the connector and even possibly tape this entire pigtail to your harness under dash.



I got the harness from Year One a few months ago and it was listed for 1970 Dodge and Plymouth models with oil gauge and I think it was made by M & H. In any event I'll tape up the connector and move on.

Thanks for the response.
Posted By: GETX

Re: 70 B body tach hole - 05/13/10 04:41 AM

Quote:

tach hole diameter 13/16"






Posted By: papajohn

Re: 70 B body tach hole - 05/14/10 01:32 AM

Quote:

Here's my February '70 LA built GTX - original tach hole.


Same as my Feb. '70 LA built Road Runner!

Attached picture 5981372-70FJ6Tachhole.JPG
Posted By: hemi68charger

Re: 70 B body tach hole - 07/07/11 12:06 AM

I believe the tach grommet was feed through the hole punch above the bulkhead connector when the car was equipped with cruise control. I believe the grommet for the cruise utilized the "normal" tach positon.

As you can see on this '69 Charger R/T equipped with cruise, you can vaguely make out the single-lead tach wire harness out of the top position.

Attached picture 6717116-dual_snorkel_aircleaner_cruise.jpg
Posted By: hemi68charger

Re: 70 B body tach hole - 07/07/11 12:14 AM

Also, as was mentioned, '70 Charger headlamp harness would have been passed through the upper hole. The tach wire harness would have come out just like the B-bodies of '68-'69, the driver's side of the bulkhead connector..
Here's a picture of the firewall of my former '70 six pack Charger R/T without the tach option. The headlamp harness grommet came out above the bulkhead connector..

Attached picture 6717135-100_9452.JPG
Posted By: DPelletier

Re: 70 B body tach hole - 07/07/11 12:15 AM

Could be; I thought it might be a Charger thing.....

In any case I'm 99% sure that a non-cruise Superbee should have it in the lower spot across from the wiring block.

Dave
Posted By: hemi68charger

Re: 70 B body tach hole - 07/07/11 12:41 AM

Quote:

Could be; I thought it might be a Charger thing.....

In any case I'm 99% sure that a non-cruise Superbee should have it in the lower spot across from the wiring block.

Dave



Dave,
If you're referring to the position between the bulkhead connector and the booster/master-cylinder like in papajohn's picture above, you are correct.......

Troy
Posted By: dart4forte

Re: 70 B body tach hole - 05/03/15 05:35 PM

Originally Posted By 70gtx440dana
Here is a picture....not sure on the size!


That's about where my tach wire comes out on my GTS
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