Picture request - factory vac gauge connections to the back of the dash

[jocko]

if anyone has a pic of the factory vac gauge connection - i.e. the dash side (rubber hose to the back of the gauge), I'd really appreciate it. I realize the "factory" vac gauge isn't a light duty truck gauge originally, but I'm retrofitting from a med duty like many of you have when I upgrade my dash. Asking because, although I have some parts on order, fittings and such, the back of the gauge I bought looks a little funky. Interested to see if anyone has, or could take, a pic of how a correct connection and/or gauge back looks. Thanks for your time.

[leddzepp]

Mark- the vac gauge used a hard line for connection. Here is a pic of the factory hard line that was used. I will post a pic of the back of my dash too (I can only post one pic at a time on my iPhone)

[leddzepp]

Back of dash. It is installed in my truck now. I will try and snap a pic of the back of it in m truck when I get home late tonight from work if nobody else does before then.

[Already Gone]

Hey Mark, I received theses pics from board member Coley showing how his vac gauge is connected. I have a dash ready for my truck and it has the vac gauge too. Its nice to get you some info when you need it because you are so good at helping everyone. Coley uses a thick rubber hose and it works great, no need for a steel line,

[jocko]

thanks very much guys - that's exactly what I needed. Are the connections for the hard line just regular old NPT at the gauge end? LMC sells a kit that I THINK allows soft line to be used and a barb that screws into the back of the gauge (but it just uses ww washer hose as the vac line, I may need a thicker wall vac hose to avoid fluctuation/poor readings - very good to hear that Coley's setup works well). All things being equal, I'll have all the parts for a soft-line approach, if I see any problems, I may upgrade to the hard line. Thanks again, really appreciate the quick response and the great pics!

[Already Gone]

Originally Posted by jocko

thanks very much guys - that's exactly what I needed. Are the connections for the hard line just regular old NPT at the gauge end? LMC sells a kit that I THINK allows soft line to be used and a barb that screws into the back of the gauge (but it just uses ww washer hose as the vac line, I may need a thicker wall vac hose to avoid fluctuation/poor readings - very good to hear that Coley's setup works well). All things being equal, I'll have all the parts for a soft-line approach, if I see any problems, I may upgrade to the hard line. Thanks again, really appreciate the quick response and the great pics!

When I install my dash ( and I plan to do it this spring/summer) I plan to do a build thread for the dash install cause I also have speedwarning on my dash, and will to be hoking that up as well.

[jocko]

I'm probably gonna hoke a few things up in the process too I always tend to do that... Looking fwd to the build. Is this for pinky or another?

[jocko]

OOPS! Ha, I KNEW I forgot about something. I have what's in pic #1 - I need to get to what's in pic 2. I have the gauges and the part that screws into the back of the cluster to hold them in, what I'm missing is the correct tin the provides the semi-circle opening for the gauge face (and hides the needle base in the process). Anyone got any leads? I KNEW I forgot something when I was gathering parts... Ha. Never fails. Not posting a WTB, just yet, but once I figure out exactly what I need to ask for, I'll do so on the parts board. Thx. (I did send TBone a pm).

[FirstOwner69]

Originally Posted by jocko

OOPS! Ha, I KNEW I forgot about something. I have what's in pic #1 - I need to get to what's in pic 2. I have the gauges and the part that screws into the back of the cluster to hold them in, what I'm missing is the correct tin the provides the semi-circle opening for the gauge face (and hides the needle base in the process). Anyone got any leads? I KNEW I forgot something when I was gathering parts... Ha. Never fails. Not posting a WTB, just yet, but once I figure out exactly what I need to ask for, I'll do so on the parts board. Thx.

You may want to PM 70shortfleet (Les). He punches tins for tachs and clocks. I'm not sure if he does the semi-circles though. If not, he may have a lead for you.

Jim

[jocko]

awesome, thanks Jim!

[FirstOwner69]

Originally Posted by jocko

awesome, thanks Jim!

Here's the link to his thread about this. Looks like he's out of town until the 14th (post 74 in thread).
http://67-72chevytrucks.com/vboard/s...ht=TACH&page=3

Also, look at posts 11 and 23 on this thread on making the hole yourself.
http://67-72chevytrucks.com/vboard/s...d.php?t=223567

[TBONE1964]

Originally Posted by jocko

OOPS! Ha, I KNEW I forgot about something. I have what's in pic #1 - I need to get to what's in pic 2. I have the gauges and the part that screws into the back of the cluster to hold them in, what I'm missing is the correct tin the provides the semi-circle opening for the gauge face (and hides the needle base in the process). Anyone got any leads? I KNEW I forgot something when I was gathering parts... Ha. Never fails. Not posting a WTB, just yet, but once I figure out exactly what I need to ask for, I'll do so on the parts board. Thx. (I did send TBone a pm).

Hey Mark, I got your PM and have you covered on the tach/vac tin. Let me know,
Thanks,
Tom

[jocko]

Youda man Tom, thanks very much. PM returned, will send payment when I confirm your paypal addr. Thx again.

[Coley]

Hey Jocko....the rubber hose works great....shows great vacuum readings, etc.
I simply 'tee'd into the hose fittings at the back of the intake manifold where there was a strong vacuum signal. Then ran the rubber hose into the cab. The vacuum gauge had a threaded fitting on the back with a small/short section of steel line so I simply pushed the hose snuggly onto that...no problems.
I can't exactly remember the hose size...but the I.D might have been close to 3/16" maybe? (I'd have to do some more checking to know for sure).
Note: Running a complete hard line is probably not possible due to the flex of the engine when torqueing over. This would be a similar situation that hard oil pressure lines need to respect by having a highly flexible 'winding' area somewhere near the block to limit a fatigue/break point. A rubber hose is certainly the best way to go on this.
All Good
Coley

[jocko]

copy all, thanks very much Coley! Piecing this thing together quickly, have been gathering parts for a while, but when it comes time to sticking it all together, always seem to forget something, ha.

[litew8]

While unorthodox, we simply used an oil pressure gauge installation kit (local auto store) to connect my (new cluster) vac gauge directly to the carb. Works great.

[jocko]

Hmm. To the carb? I guess from the base is a good signal, I normally see these connected to the manifold T behind the carb. Probably same signal anyway - that's a good idea, thankslitew8. I'll see what I've got on the shelf, think I have the manifold connection suitcased, but if not, I'll keep this in mind. Thank you.

Tom, payment sent. Thanks for savin my bacon so quickly!

[litew8]

You're welcome, np man.
I'll need to secure it better, but you can see it on the base/left in this pic.
We figured the line doesn't need to be large at all (so long as there's good vaccum).
The connectors provided with the kit worked well on the backside of the gauge.

[TBONE1964]

Originally Posted by jocko

Hmm. To the carb? I guess from the base is a good signal, I normally see these connected to the manifold T behind the carb. Probably same signal anyway - that's a good idea, thankslitew8. I'll see what I've got on the shelf, think I have the manifold connection suitcased, but if not, I'll keep this in mind. Thank you.

Tom, payment sent. Thanks for savin my bacon so quickly!

Not a problem at all Mark, glad to help and thank you also.

Anything at the base of the carb and below will give you the same vacuum reading, regardless of where you hook it. The base of the carb should be the same as manifold vacuum.

[litew8]

I agree TBONE, pressure should be the same, for both areas, since it (pressure) is being produced from below. The line we used turned out clean, no clutter and the line passed through an existing opening on the firewall with ease.

[leddzepp]

The OEM hard line does not connect to the engine. It ties into the power brakes on the larger trucks close to the firewall, and really has nowhere to make a direct connection on our trucks. I added a rubber hose to the end and ran it to a vacuum tee pretty much the same as Coley has pictured.

[cdowns]

since no vaccume gauge was available for smaller c10 c20 type trucks hook up depends on how you want it to be

[chewychevy67]

this is how I did mine. the thread matches the one on the back of the gauge. it will be hooked up to this using the same couplers as the gauge.

[Already Gone]

Originally Posted by chewychevy67

this is how I did mine. the thread matches the one on the back of the gauge. it will be hooked up to this using the same couplers as the gauge.

Rod, can you explain all you are going to hook up to this fitting? I'm thinking the small brass threaded fitting is for the vacuum gauge and the larger threaded connector goes into your manifold and that still leaves one threaded connector and two hose connectors.

[jocko]

yep, I'm a little cornfused also. I am assuming that is just your manifold vac tee and you're hooking a hard line to the vac gauge where you have the brass fitting screwed in? If that is the case, you will need to account for eng vs body vibe as was mentioned above. Even if a hard line is used, there has to be rubber in the process somewhere to account for that. Or I might not be interpreting what you're doing correctly.

Thanks for posting EVERYone - this has been very helpful to me.